CN211127644U - Variable-current control device and motor - Google Patents

Abstract

The utility model discloses a variable flow control device and motor, the device includes: a current transformation unit and a control unit; the converter unit is used for outputting three-phase alternating current to the motor after single-phase alternating current is converted; wherein, the variable flow treatment comprises: rectifying, filtering and inverting; and the control unit is used for acquiring the variable flow parameters of the variable flow unit and the operating parameters of the motor, and performing phase shift modulation and circulation layered control on the variable flow unit according to the variable flow parameters and the operating parameters to realize layered closed-loop control between the variable flow unit and the motor. The utility model discloses a scheme can solve the topological mode that adopts two level inversions and make the problem that output waveform harmonic content is high, reaches the effect that reduces output waveform's harmonic content.

Description

Variable-current control device and motor

Technical Field

The utility model belongs to the technical field of the unsteady flow, concretely relates to unsteady flow control device and motor especially relate to a novel unsteady flow control motor system of modular and motor.

Background

With the development of digitization technology and energy conversion efficiency, the novel power electronic technology has wide application in the field of modern electric energy technology. Some household appliances and civil inverters mostly adopt a two-level inversion topological mode, power consumption of power device elements is large, and output waveform harmonic content is high. In some products, the energy consumption and the product use performance are seriously influenced, and more filtering elements are required.

The above is only for the purpose of assisting understanding of the technical solutions of the present invention, and does not represent an admission that the above is the prior art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to above-mentioned defect, provide a variable flow control device and motor to solve the problem that adopts two level contravariant topological mode to make output waveform harmonic content high, reach the effect that reduces output waveform's harmonic content.

The utility model provides a variable flow control device, include: a current transformation unit and a control unit; the converter unit is used for outputting three-phase alternating current to the motor after single-phase alternating current is converted; wherein, the variable flow treatment comprises: rectifying, filtering and inverting; and the control unit is used for acquiring the variable flow parameters of the variable flow unit and the operating parameters of the motor, and performing phase shift modulation and circulation layered control on the variable flow unit according to the variable flow parameters and the operating parameters to realize layered closed-loop control between the variable flow unit and the motor.

Optionally, the converter unit comprises: the device comprises a modular single-phase rectification module, a filtering module and a modular three-phase inversion module; the modular single-phase rectification module is used for rectifying single-phase alternating current and outputting direct-current bus voltage; the filtering module is used for filtering the direct current bus voltage after the single-phase alternating current is rectified so as to obtain the direct current bus voltage after filtering; and the modular three-phase inversion module is used for performing inversion processing on the filtered direct-current bus voltage and outputting three-phase alternating current, specifically three-phase alternating voltage.

Optionally, a modular single-phase rectification module, comprising: the single-phase rectification bridge comprises a boosting module, a single-phase rectification upper bridge arm and a single-phase rectification lower bridge arm; the boost module is arranged between the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm, and is used for boosting single-phase alternating current and then respectively transmitting the single-phase alternating current to the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm for rectification; each of the single-phase rectification upper bridge arm and/or the single-phase rectification lower bridge arm comprises: a single-phase rectifier sub-module; the number of the single-phase rectifier sub-modules is a first set value, and the single-phase rectifier sub-modules with the first set value are arranged in a cascade mode; each single-phase rectifier sub-module comprising: the single-phase full-bridge rectifier submodule and/or the single-phase half-bridge rectifier submodule.

Optionally, a modular three-phase inversion module, comprising: the voltage reduction module, the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm; the voltage reduction module is arranged between the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm and is used for carrying out voltage reduction on three-phase alternating current subjected to inversion processing by the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm and outputting the three-phase alternating current to the motor; each of the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm comprises: a three-phase inversion submodule; the number of the three-phase inversion sub-modules is a second set value, and the three-phase inversion sub-modules with the second set value are arranged in a cascade mode; each three-phase inversion submodule comprises: and the three-phase full-bridge inversion submodule and/or the three-phase half-bridge inversion submodule.

Optionally, the method further comprises: a protection unit; and the protection unit is used for filtering the zero-fire ground wire of the commercial power to form single-phase alternating current.

Optionally, a control unit comprising: a phase shift modulation module; and the phase shift modulation module is used for outputting pulse signals to the rectification processing side and the inversion processing side in the current conversion unit respectively by utilizing two independent sawtooth waves and adopting a phase shift modulation technology and a circulation layered control mode so as to drive the rectification processing side and the inversion processing side in the current conversion unit through the pulse signals.

Optionally, the control unit further includes: a rectification side sampling module; the rectifying side sampling module is used for collecting a direct-current bus signal at a rectifying processing side in the converter unit, the bridge arm voltage of each bridge arm and/or the capacitor voltage of each single-phase rectifier submodule; and the phase-shift modulation module is further used for adjusting the pulse signal at the rectification processing side in the current transformation unit based on a sawtooth carrier phase-shift modulation technology according to the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule, so as to realize the balance control of the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule.

Optionally, the control unit further includes: an inversion side sampling module; the inversion side sampling module is used for collecting three-phase electric signals at an inversion processing side in the current transformation unit, bridge arm inner ring currents of each bridge arm and/or capacitance voltages of each three-phase inversion submodule; and the phase-shifting modulation module is also used for adjusting the pulse signal at the inversion processing side in the current transformation unit according to the three-phase electric signal at the inversion processing side, the bridge arm inner ring current of each bridge arm and/or the capacitance voltage of each three-phase inversion submodule, so as to realize the outer ring control and the interphase balance of the three-phase electric signal at the inversion processing side, the bridge arm inner ring current suppression of each bridge arm and/or the layered control of the capacitance voltage balance of each three-phase inversion submodule.

Optionally, the control unit further includes: a load side sampling module; the load side sampling module is used for collecting the three-phase current, the rotor position and/or the rotor speed of the motor at the output side of the converter unit; and the phase shift modulation module is also used for adjusting pulse signals at a rectification processing side and/or an inversion processing side in the current conversion unit according to the three-phase current, the rotor position and/or the rotor speed of the motor so as to realize closed-loop frequency conversion control of the motor at the output side of the current conversion unit.

With the above device phase-match, the utility model discloses another aspect provides a motor, include: the variable flow control device described above.

The scheme of the utility model, through adopting the topological structure of submodule piece single-phase full-bridge rectifier circuit and three-phase half-bridge contravariant cascade circuit, through sawtooth wave phase shift modulation and equalizer flow control theory, guaranteed that the energy conversion of each phase of converter circuit and each submodule piece is balanced, solve the problem that the power consumption of the topological mode power device component that adopts two-level contravariant is big, reach the effect that reduces power device component power consumption; the problem of the power loss distribution imbalance of the sub-modules is further solved, and the power consumption of power components is reduced.

Further, the utility model discloses a scheme, through adopting the topological structure of submodule piece single-phase full-bridge rectifier circuit and three-phase half-bridge contravariant cascade circuit, through sawtooth wave phase shift modulation and equalizer flow control theory, the three-phase alternating voltage of final output triggers the drive for two-level IGBT, and harmonic content is less, can realize the smooth control operation of motor; therefore, the problem that the higher harmonic content of the voltage waveform output by inversion is high is solved, and the control effect of the motor is obvious.

Further, the utility model discloses a scheme is through adopting two independent sawtooth carrier wave phase shift techniques, based on modularization circulation restraines layering balance control and RFOC closed-loop control principle, establishes inside and outside multilayer control loop and controls rectification side bus voltage and contravariant side three-phase frequency conversion voltage output respectively, realizes synchronous compression motor frequency conversion drive control, has reduced power device IGBT's energy loss, and outputs three-phase voltage harmonic content and obviously reduces.

Therefore, the utility model discloses a scheme, through the modularization cascade conversion topological structure that adopts single-phase full-bridge rectifier module side and three-phase half-bridge contravariant module side to form, input single-phase alternating current, output three-phase alternating voltage solves the topological mode that adopts the contravariant of two levels and makes the high problem of output waveform harmonic content, reaches the effect that reduces output waveform's harmonic content.

The modular cascade conversion topological structure formed by the single-phase full-bridge rectification module side and the three-phase half-bridge inversion module side is a flexible conversion cascade topological structure, and can flexibly realize the frequency conversion modulation output of the motor power.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and examples.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of a variable flow control device of the present invention;

FIG. 2 is a schematic diagram of a control system for one embodiment of a variable flow air conditioner compressor;

FIG. 3 is a schematic diagram of an embodiment of a single module on the rectifying and inverting sides of the converter;

FIG. 4 is a schematic diagram of another embodiment of a single module on the rectifying and inverting sides of the converter;

fig. 5 is a schematic diagram of a topological structure of an embodiment of a multilevel cascaded converter when an interphase bridge arm module is 6; the structure of the first part of the multilevel cascaded converter is shown in the specification, (a) the structure of the second part of the multilevel cascaded converter is shown in the specification, (b) the structure of the third part of the multilevel cascaded converter is shown in the specification, and (d) the structure of the fourth part of the multilevel cascaded converter is shown in the specification;

fig. 6 is a schematic structural diagram of an embodiment of a topology overall driving control system of a cascaded converter, wherein (a) is an overall structural diagram, and (b) is a structural diagram of a sawtooth carrier phase shift modulation module;

FIG. 7 is a block diagram of an embodiment of a hierarchical control of drive system modules; the structure schematic diagram of the capacitor voltage layered balance control is shown in the specification, wherein (a) is a structure schematic diagram of the capacitor voltage layered balance control, b is a structure schematic diagram of a phase balance control ring, c is a structure schematic diagram of an upper bridge arm balance control ring and a lower bridge arm balance control ring, d is a structure schematic diagram of a circulating current suppression control ring, and e is a structure schematic diagram of an MMC sub-module energy balance control ring;

fig. 8 is a schematic structural diagram of an embodiment of a control strategy loop on the modular converter-inverter side and the rectifier side, wherein (a) is a schematic structural diagram of RFOC modular converter-inverter control of a synchronous motor, (b) is a schematic structural diagram of rectifier side PI control, and (c) is a schematic structural diagram of rectifier side closed-loop equalization control;

fig. 9 is a schematic flow chart of an embodiment of a variable flow control method according to the present invention;

fig. 10 is a schematic flow chart illustrating an embodiment of a method of converting a single-phase ac current according to the present invention;

fig. 11 is a schematic flow chart illustrating an embodiment of controlling the pulse signal of the converter unit according to the rectification side in the method of the present invention;

fig. 12 is a schematic flow chart illustrating an embodiment of controlling the pulse signal of the converter unit according to the inversion side in the method of the present invention;

fig. 13 is a schematic flow chart illustrating an embodiment of controlling the pulse signal of the converter unit according to the load side in the method of the present invention.

Detailed Description

To make the purpose, technical solution and advantages of the present invention clearer, the following will combine the embodiments of the present invention and the corresponding drawings to clearly and completely describe the technical solution of the present invention. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

According to an embodiment of the present invention, a converter control device is provided. Referring to fig. 1, a schematic structural diagram of an embodiment of the apparatus of the present invention is shown. The variable flow control device may comprise: the current transformation unit is a cascade current transformation module and a control unit. The converter unit and the control unit can be sequentially arranged between the alternating current power supply and the electric equipment such as a motor.

Specifically, the converter unit is a modular single-phase-three-phase cascade converter topology, and can be used for outputting three-phase alternating-current voltage to electric equipment after single-phase alternating current is subjected to converter processing. The modular single-phase-three-phase cascade converter topology is a flexible converter cascade topology structure, and can flexibly realize the frequency conversion modulation output of the motor power. An electrical device may include: an electric motor such as an air conditioning compressor. The variable flow processing may include: rectification processing, filtering processing and inversion processing.

In an alternative example, the converter unit may include a modular single-phase rectification module, a filtering module, and a modular three-phase inversion module, the modular single-phase rectification module may be a single-phase modular full-bridge rectification circuit, the filtering module may be an L C filtering circuit, the modular three-phase inversion module may be a three-phase modular half-bridge inversion circuit, an output of the modular single-phase rectification module may be connected to an input of the modular three-phase inversion module, and the filtering module may be disposed between the modular single-phase rectification module and the modular three-phase inversion module.

Specifically, the modular single-phase rectification module can be used for outputting direct-current bus voltage after rectifying single-phase alternating current such as single-phase AC.

Specifically, the filtering module may be configured to perform filtering processing on the dc bus voltage after the single-phase ac is rectified, so as to obtain the dc bus voltage after the filtering processing.

Specifically, the modular three-phase inversion module can be used for inverting the filtered direct-current bus voltage and outputting three-phase alternating current, specifically can be used for outputting three-phase alternating current voltage and can be used as driving voltage of a motor such as a compressor.

For example: the inverter topology structure of the modular converter is adopted for the compressor driving circuit, the on-off time of a single power device is reduced, and the energy loss of the IGBT of the power device is reduced. The direct current bus steady state output ripple at the rectification side is smooth, the output at the inversion side can be used for controlling the synchronous motor, the requirements under the conditions of different bus voltages, output power and rotating speed can be met, and the speed regulation range is more flexible.

For example, the cascade conversion module of the system adopts single-phase full-bridge rectification and three-phase half-bridge inversion, and parts of the cascade conversion module adopt IGBT modular cascade, the middle part of the cascade conversion module adopts L C filter circuit link, so that the DC fluctuation of an output direct-current bus is ensured to be smaller, and the part of the cascade conversion module can realize three-phase variable-current output with smaller harmonic wave and higher power factor.

Therefore, single-phase alternating current is subjected to current transformation processing through the modularized single-phase rectification module, the filtering module and the modularized three-phase inversion module, and the modularized single-phase rectification module and the modularized three-phase inversion module are adopted, so that the energy loss of a power device can be reduced due to the fact that the on-off time of the single power device is shortened. The direct current bus on the rectifying side has smooth steady-state output ripples, so that the harmonic content of three-phase alternating current voltage output by the inverting side is low, the voltage waveform of inverting output is optimized, and stable control operation of electric equipment such as a motor is facilitated.

Optionally, the modular single-phase rectification module may include: the boost converter comprises a boost module (such as a rectification side inductor), a single-phase rectification upper bridge arm and a single-phase rectification lower bridge arm.

Specifically, the boost module is arranged between the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm, and can be used for boosting single-phase alternating current and then respectively transmitting the single-phase alternating current to the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm for rectification.

Specifically, each of the single-phase rectification upper bridge arm and/or the single-phase rectification lower bridge arm may include: and a single-phase rectifier sub-module. The number of the single-phase rectifier sub-modules is a first set value, and the single-phase rectifier sub-modules with the first set value are arranged in a cascade mode. Each single-phase rectifier sub-module may include: the single-phase full-bridge rectifier sub-module and/or the single-phase half-bridge rectifier sub-module, of course, may preferably be a single-phase full-bridge rectifier sub-module.

For example: for a rectification side circuit, a single-phase full-bridge Modular Multilevel Converter (MMC) topological structure is adopted. The clean and reliable single-phase alternating current formed by the zero-fire ground wire of the commercial power after strong current filtering is subjected to modular rectification by the upper and lower bridge arms to form adjustable direct current bus voltage, so that the design of an actual product is more met, and the output and control of the rectification side are more flexible due to the cascade connection of IGBT component topology. Meanwhile, the part replaces a PFC circuit, and power factor correction can be realized. The harmonic content of the output three-phase voltage is obviously reduced, the capacity of a filter is reduced, and the cost reduction effect of the controller is obvious.

For example: the modular full-bridge topology sub-circuit is characterized in that N IGBTs are connected in series two by two and then connected in parallel, each phase of an alternating current signal is divided into an upper bridge arm and a lower bridge arm, and each bridge arm can adopt N full-bridge topology sub-modules. The number of IGBTs in the bridge arm sub-modules is 4, and the number of the bridge arm sub-modules (SM) is 3. On the rectifying side, the AC power supply is boosted through an inductor to transfer energy after filtering, then the full-bridge submodule on the rectifying side is switched on and rectified, the output voltage is subjected to energy storage filtering through a sub-capacitor, and finally the direct-current bus voltage U with smaller ripples is output in a superposed mode_dc. The bridge arm sub-modules of the full-bridge module on the rectifying side are 4 IGBT cascade topologies, the scheme is low in output ripple, and meanwhile, the power factor correction function is achieved, and PFC structures in some controllers are replaced.

Therefore, the boost module, the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm form the modularized single-phase rectification module, boost and rectification processing of single-phase alternating current are achieved, steady-state output ripples of a direct-current bus on a rectification side can be smooth, and reduction of harmonic content of three-phase alternating-current voltage finally output through inversion is facilitated.

Optionally, the modular three-phase inversion module may include: a voltage reduction module (such as an inversion side inductor), a three-phase inversion upper bridge arm and a three-phase inversion lower bridge arm.

Specifically, the voltage reduction module is arranged between the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm, and can be used for carrying out voltage reduction on three-phase alternating current subjected to inversion processing by the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm and then outputting the three-phase alternating current to the motor.

For example, the upper and lower bridge arms on the inverting side are respectively connected with an inductor (L)_s) The three-phase synchronous compression motor can be used for voltage reduction, and voltage signals can act on the three-phase synchronous compression motor through the output of the inductor.

Specifically, each of the three-phase inversion upper leg and the three-phase inversion lower leg may include: and a three-phase inversion submodule. The number of the three-phase inversion sub-modules is a second set value, and the three-phase inversion sub-modules with the second set value are arranged in a cascade mode. Each three-phase inversion submodule may include: the three-phase full-bridge inverter submodule and/or the three-phase half-bridge inverter submodule can be selected, and of course, the three-phase half-bridge inverter submodule can be selected.

For example: the inverter topology of the cascade half-bridge IGBT module adopts internal and external double-loop control, so that the control output is more flexible, and the operation of the synchronous motor under the conditions of different output powers or rotating speeds can be met.

For example: on the inversion side, the DC bus voltage U_dcAs the inversion input side comes from the modular multi-level rectification, the output range is flexible. DC bus voltage U_dcThree-phase alternating current U converted into control motor through modular inversion topology_A、U_B、U_C. The submodule of the modular half-bridge inverter topology adopts a topological structure that N IGBTs are connected in series two by two and then cascaded, and N is a natural number.

If the number of IGBTs in the sub-module is 2, the sub-module capacitor voltage is U_{c_j}The IGBT switching voltage is V_x. Simultaneously, three-phase output comes from three contravariant bridge arm, and is the same with the rectification side, and the bridge arm of every looks of this part can adopt a N half-bridge submodule piece topology the utility model discloses a quantity of bridge arm submodule piece (SM) can be 3 in the scheme.

Therefore, the voltage reduction module, the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm form the modularized three-phase inversion module, three-phase inversion of direct-current bus voltage obtained by boosting and rectifying single-phase alternating current is achieved, three-phase alternating current voltage with low harmonic content can be output, and stable operation of a driving motor is facilitated.

Therefore, preferably, a single-phase full-bridge rectification-three-phase half-bridge inversion conversion topology is adopted, and meanwhile, control loops such as magnetic flux vectors, power and the like of a motor system are introduced, so that the non-fixed frequency is realized, and the actual speed regulation control of the synchronous compression motor is better met. More specifically, the rectification side is an alternating current voltage source, and the motor system adopts the RFOC and the power speed regulation control loop to regulate the speed.

Therefore, a novel modularized cascade current transformation topological structure is adopted, the structure is divided into a single-phase full-bridge rectifier module side and a three-phase half-bridge inverter module side, single-phase alternating current is input, three-phase alternating current voltage is output, and the two parts are modularized signal layered control. Through modularization single-phase rectification module and modularization three-phase contravariant module, can form modularization single-phase full-bridge rectification + modularization half-bridge contravariant and cascade topology structure, bridge arm submodule quantity can be according to the nimble setting of user demand if can set up to 3, and the output load is three-phase synchronous motor. The input side voltage is: after strong electrical filtering, the single-phase AC input at the rectifying side is rectified. The carrier control mode is as follows: sawtooth carrier phase shift + rotor flux linkage directional control (i.e., RFOC control).

The first set value and the second set value may be the same or different. That is to say, the number of the sub-modules in each bridge arm can be flexibly set according to the use requirement. For example, the number of the upper and lower bridge arm sub-modules of the rectification and inversion module is 3. The rectification inversion is a modular multilevel topology, the rectification is a single-phase full-bridge topology, the inversion is a three-phase half-bridge topology, and the upper and lower bridge arms of each phase are connected in series by 3 sub-modules (N is 3).

For example: it is suitable for three-phase power output systems of different grades, but in high power systems, such as megawatt systems, the number of sub-modules required is large. More sub-modules can effectively restrain higher harmonics, protect the system and be more suitable for being applied to a power system.

For another example: the method can also be applied to synchronous motor drive circuits with different powers, such as the variable-frequency speed-regulating closed-loop control of a synchronous compressor can be realized through rotor flux linkage directional control (RFOC) and carrier phase-shifting PWM pulse modulation. The advantages of air conditioner series products in the aspect of variable frequency driving can be enhanced, the performance quality and the electric energy utilization rate of the products are enhanced, and the service life of the products can be greatly prolonged due to the balanced power of the sub-modules.

Specifically, the control unit may be configured to obtain a variable flow parameter of the variable flow unit and an operating parameter of the motor, and perform phase shift modulation and loop current hierarchical control on the variable flow unit according to the variable flow parameter and the operating parameter, so as to implement hierarchical closed-loop control between the variable flow unit and the motor.

For example: a modular single-phase full-bridge rectification and multilevel half-bridge three-phase inversion cascade current transformation topology control system adopts two independent sawtooth carrier phase shifting technologies, and establishes an inner multilayer control loop and an outer multilayer control loop to respectively control the output of a rectification side bus voltage and an inversion side three-phase variable frequency voltage based on a modular circulation suppression hierarchical balance control and RFOC closed-loop control principle, so as to realize the variable frequency drive control of a synchronous compression motor.

For example, aiming at a low-power compressor in the field of household air conditioners, a design scheme of a single-cylinder compressor variable flow control system controlled by a novel converter structure is provided. Based on the control circuit of the air conditioner compressor, the topological structure of the submodule single-phase full-bridge rectification circuit and the three-phase half-bridge inversion cascade circuit is adopted, and the energy conversion balance of each phase and each submodule of the converter circuit is guaranteed through sawtooth wave phase shift modulation and equalizing ring flow control theories. The finally output three-phase alternating voltage is triggered and driven relative to the two-level IGBT, the harmonic content is low, and stable control operation of the motor can be realized. Therefore, the problem of unbalanced power loss distribution of the submodules is solved, the problem of more higher harmonic content of voltage waveform output by inversion is optimized, and the control effect of the motor is obvious.

Therefore, through the current transformation unit and the control unit, current transformation processing is carried out based on the single-phase intersection current point, and phase shift modulation and circulation control are carried out on the current transformation unit, so that the problem of large power consumption of a power device element in a topological mode of adopting two-level inversion can be solved, namely the problem of unbalanced power loss distribution of sub-modules is solved, and the power consumption of the power device element is reduced; the problem that the higher harmonic content of the voltage waveform output by inversion is high can be solved, the harmonic content is reduced, and stable control operation of electric equipment such as a motor is facilitated.

In an alternative example, the control unit may include: the phase shift modulation module, such as a sawtooth wave phase shift modulation module, may be connected to the single-phase modular full-bridge rectifier circuit and the three-phase modular half-bridge inverter circuit in the converter unit, respectively.

Specifically, the phase shift modulation module may be configured to output pulse signals to a rectification processing side and an inversion processing side of the converter unit respectively by using two independent sawtooth waves and adopting a phase shift modulation technique and a loop hierarchical control manner, for example, pulse signals, preferably PWM pulse signals, are output to a modular single-phase rectification module and a modular three-phase inversion module of the converter unit respectively, so as to drive the rectification processing side and the inversion processing side of the converter unit by the pulse signals.

For example: two independent sawtooth waves are generated by a DSP (digital signal processor) or a hardware analog circuit, and PWM (pulse width modulation) pulse signals are respectively output to each submodule of a single-phase rectifier bridge arm and a three-phase modular inverter bridge arm by adopting a phase shift modulation technology and a circulation hierarchical control mode.

For example: the modulation system adopts two independent control loops to respectively carry out multipath output on the rectifying side and the inverting side, and the PWM mode combining the full bridge and the half bridge enables the system to be controlled more flexibly. The overall control mode of the system can be divided into rectification side direct current modular control and inversion side motor variable frequency drive control. Both adopt a sawtooth carrier phase-shift modulation technology and layered circulation balance control, and are characterized in that a rectifying side takes DC bus voltage as an output reference signal, and an inverting side takes actual variable frequency rotating speed or PQ control as reference point closed-loop control.

Therefore, through the phase shift modulation module, pulse signals are respectively output to the rectification processing side and the inversion processing side based on two independent sawtooth waves through a phase shift modulation technology and a circulation layered control mode, the rectification processing side and the inversion processing side can be independently driven, and the reliability of driving can be guaranteed.

Optionally, the control unit may further include: and the rectification side sampling module, such as a rectification side alternating current and direct current voltage sampling module, a sub-module capacitance and voltage sampling module and the like. Wherein, the control unit carries out phase shift modulation and circulation layered control to the converter unit, and can also include: and controlling the process of the pulse signal of the current transformation unit according to the rectification side.

Specifically, the rectification-side sampling module may be configured to collect a direct-current bus signal at a rectification processing side in the converter unit, a bridge arm voltage of each bridge arm (that is, a bridge arm voltage of each bridge arm in the single-phase rectification upper bridge arm and/or the single-phase rectification lower bridge arm), and/or a capacitance voltage of each single-phase rectification submodule (that is, a single-phase rectification submodule in each bridge arm). The dc bus signal may include a dc bus voltage, a dc bus current, and the like.

Specifically, the phase shift modulation module may be further configured to use a single-phase closed-loop control circuit that uses a dc bus voltage output by the rectification side as a reference, and adjust the pulse signal at the rectification side in the current transformation unit based on a sawtooth carrier phase shift modulation technique according to the dc bus signal at the rectification side, the bridge arm voltage of each bridge arm, and/or the capacitor voltage of each single-phase rectification submodule, so as to implement equalization control of the dc bus signal at the rectification side, the bridge arm voltage of each bridge arm, and/or the capacitor voltage of each single-phase rectification submodule.

For example: the rectifying side adopts a single-phase closed-loop control loop taking the output direct-current bus voltage as a reference, and based on a sawtooth carrier phase-shift modulation technology, the direct-current bus voltage, the current, the bridge arm voltage and the submodule capacitor voltage are respectively subjected to balanced control, so that the direct-current bus voltage output of different grades under constant alternating current is realized.

For example: the rectification switch device topology adopts a sawtooth carrier phase shift modulation technology as a PWM modulation signal, under the action of 220VAC voltage, the interphase energy balance, the total voltage of each phase bridge arm and the capacitor voltage of each submodule are respectively detected, and the amplitude of the output voltage of the rectification side can be controlled along with the duty ratio of the conduction of a rectification submodule switch (SMn). For example, the PI closed-loop control circuit on the rectifying side obtains the direct current by taking the direct current output power or the direct current bus voltage as a reference point and calculating with the actually sampled direct current bus currentReference voltage U of current bus_refAnd then, a PWM driving signal which can be used for adjusting the full-bridge submodule is obtained through a sawtooth carrier signal comparator, and the output of a direct current bus is controlled.

For the rectification feedback loop, the control mode adopts a voltage energy layered transmission mode. The method mainly comprises inner and outer ring control, wherein the inner ring adopts phase voltage balance control, bridge arm voltage balance control, sub-module capacitor voltage balance, and feedback reference signal is power or DC bus direct current voltage U_dc. The carrier phase shift at the rectification side adopts N sawtooth waves to sequentially shift the phase by pi/N so as to obtain the optimal harmonic elimination characteristic, namely the range of the carrier phase shift angle is 0-pi/2N.

Therefore, through a single-phase closed-loop control loop taking the output direct-current bus voltage as a reference on a rectification side, based on a sawtooth carrier phase-shift modulation technology, direct-current bus voltage, current, bridge arm voltage and submodule capacitor voltage are respectively subjected to balanced control, direct-current bus voltage output of different levels under constant alternating current is realized, and flexible adjustment of the output direct-current bus voltage can be realized.

Optionally, the control unit may further include: and the inverter side sampling module, such as an inverter side three-phase current and voltage sampling module, a sub-module capacitor and voltage sampling module and the like. Wherein, the control unit carries out phase shift modulation and circulation layered control to the converter unit, and can also include: and controlling the pulse signal process of the current transformation unit according to the inversion side.

Specifically, the inversion side sampling module may be configured to collect a three-phase electrical signal at an inversion processing side in the converter unit, an inner ring current of a bridge arm of each bridge arm (that is, an inner ring current of each bridge arm of the three-phase inversion upper bridge arm and/or the three-phase inversion lower bridge arm), and/or a capacitive voltage of each three-phase inversion submodule (that is, a three-phase inversion submodule in each bridge arm). Wherein, three-phase electric signal can include: three-phase voltage signals, three-phase current signals, and the like.

Specifically, the phase shift modulation module can also be used for a closed-loop control circuit which takes the rotating speed and the output power of a motor driven by three-phase alternating current output by the inversion processing side as reference, and adjusts the pulse signal of the inversion processing side in the current transformation unit according to the three-phase electric signal of the inversion processing side, the bridge arm inner ring current of each bridge arm, and/or the capacitance voltage of each three-phase inversion submodule, so that the outer ring control and the phase-to-phase balance of the three-phase electric signal of the inversion processing side, the bridge arm inner ring current suppression of each bridge arm, and/or the layered control of the capacitance voltage balance of each three-phase inversion submodule are realized.

For example: the inversion side sub-module of the current transformation module is of a 2 IGBT cascade half-bridge structure, the rotation speed and the output power of an acting synchronous motor are taken as reference, and three-phase variable frequency voltage and current output is realized through a layered control mode of outer ring voltage control, phase-to-phase balance, bridge arm inner ring current suppression and sub-module capacitor voltage balance. Such as a sawtooth phase-shifted carrier wave to control the full-bridge PWM output. The outer ring establishes a control loop through the output voltage and power of the rectifying side, and voltage requirements of the inverting side in different grades in a requirement interval are met. The double-loop control can independently act on a rectification inversion outer loop, but the inner layers are controlled in a layered mode, and the voltage balance of the module capacitor is met.

The direct-current bus voltage output by the modularized rectifying side enters the modularized multi-level inverter circuit after being filtered by the capacitor. The inverter circuit adopts a half-bridge submodule structure with double IGBTs connected in parallel, and adopts the rotating speed or power as the feedback regulation of the rotor flux linkage directional control (RFOC) of the whole motor system, so that the module outputs a three-phase alternating current signal. The first stage is the overall control of a variable flow feedback system, the outer ring control is the motor rotating speed control or the output power control, and the inner ring is the current control of a dq0 rotating coordinate system. The second stage of the modular inversion is interphase balance control. The third stage is bridge arm balance control. And in the fourth stage, the capacitor voltage of the submodules is balanced, each submodule of each bridge arm corresponds to an independent control ring, and the reference voltage of each control ring is one N times of the capacitor voltage of the bridge arm where the control ring is located.

For example: in the step of outer ring parameter control, the current signal I output by three phases is sampled_A、I_B、I_CThe ac component is converted to a dc component in dq quadrants by park and clark conversion. And simultaneously sampling signals of torque, position, angular speed and the like of the motor stator load. With external referenceI of q quadrant formed by PI operation according to given value_qThe component is given a value. I of d quadrant in the system_dThe component setpoint is initially 0. When relevant direct current components (position, angular velocity, torque power and the like) are used as output reference components to be injected into a system, components in dq quadrants are inversely transformed and converted into alternating current components which can act on a motor system, and the output of the alternating current components is mainly three-phase reference voltage.

For example: sampling upper and lower bridge arm capacitance voltage signal U on each submodule_{c_pj(n)}、U_{c_nj(n)}. And simultaneously, the voltage signals obtained in the last step are injected into a modulation system together. The modulation system adopts sawtooth carrier phase shift modulation, and forms PWM fundamental waves on each submodule after PI iterative operation is carried out on submodule capacitor voltage and three-phase voltage signals. Then the fundamental waves on the upper and lower bridge arms are compared with the phase-shifted sawtooth carrier waves for operation to form a plurality of paths of PWM output signals on the rectifier module and the inverter module, and a gate signal on each IGBT in the topology is controlled.

Therefore, through a single-phase closed-loop control circuit taking the output direct-current bus voltage as a reference on a rectification side, based on a sawtooth carrier phase-shifting modulation technology, the outer ring control and the layered control of phase-to-phase balance, bridge arm inner ring current suppression and capacitance voltage balance of three-phase electric signals are respectively realized, and the flexible adjustment of three-phase variable-frequency voltage and current output can be realized.

Optionally, the control unit may further include: and the load side sampling module is used for sampling the position and the speed of the motor. Wherein, the control unit carries out phase shift modulation and circulation layered control to the converter unit, and can also include: and controlling the process of the pulse signal of the current transformation unit according to the load side.

Specifically, the load side sampling module may be configured to collect three-phase currents, a rotor position, and/or a rotor speed of an output side motor of the converter unit.

Specifically, the phase shift modulation module may be further configured to use a closed-loop control circuit that refers to a rotation speed and an output power of a motor driven by a three-phase alternating current output from the inverter processing side, and adjust a pulse signal at the rectification processing side and/or the inverter processing side of the converter unit according to the three-phase current of the motor, a rotor position, and/or a rotor speed, so as to implement closed-loop frequency conversion control on the motor at the output side of the converter unit.

For example: the modular cascade converter outputs and acts on the synchronous compressor. The output end monitors three-phase current, rotor position and speed, meanwhile, power regulation and rotating speed reference point regulation are added to the input end respectively, and the whole new control system realizes closed-loop variable frequency control on the compressor in an RFOC mode.

For example: and the rectification module and the sub-modules in the inversion module are controlled in a carrier phase-shifting layered mode, and single-phase alternating current is rectified and then inverted to output alternating current signals capable of enabling the three-phase motor to carry out frequency conversion. The whole external control loop of the two parts, direct current bus voltage closed loop feedback control and RFOC motor rotating speed control respectively and independently control the respective modules, so that the regulation capability of the whole converter system is more flexible.

The specific hierarchical control strategy of the carrier phase shift modulation is that upper and lower bridge arms of the rectification and inversion parts cannot be simultaneously switched on, so that the fundamental wave signal needs to be inverted, then the carrier phase shift angle full bridge shifts the phase of each submodule by 2 pi/N, and the half bridge is pi/N. The outer loop control is motor RFOC closed-loop control, is different from direct output three-phase voltage, and the reference point of the system is mainly stator rotating speed or torque, and the control mode can be diversified by combining with actual requirements.

Therefore, by monitoring the three-phase current at the output side of the converter unit, the position and the speed of the motor yoke rotor and the like, and simultaneously adding power regulation and rotating speed reference point regulation to the input end respectively, the closed-loop variable frequency control of the compressor can be realized, and the operation stability of the motor can be further ensured.

In an alternative embodiment, the method may further include: and a protection unit. The protection unit, such as a strong electric filtering and protection circuit, may be disposed between an AC power source, such as 220V AC, and a current transforming unit, such as a cascaded current transforming module.

Referring to the example shown in fig. 4, the 220V AC line of the zero-fire ground line of the utility power supply is a zero-fire ground line (i.e., N, L, PE), and then the stable and clean single-phase AC power is output through the strong electric filtering and protecting module (i.e., two lines L and N), so that the clean and stable state refers to reduction of interference (harmonic waves, etc.) in the external power grid through secondary filtering.

For example: when a power supply is started, a zero-fire ground wire port connected to a mains supply outputs a single-phase alternating-current voltage through a strong-current secondary filter circuit, meanwhile, a strong-current filter and protection circuit (such as a discharge control chip) is added to the zero-fire wire output port, the circuit is broken when the AC power exists, a short circuit is formed when the AC power is disconnected, rapid discharge is formed, and residual voltage of a large capacitance device in a system is released.

For example: the 220V alternating voltage passes through a zero-fire ground wire strong electric filtering protection circuit and outputs single-phase alternating voltage. The single phase voltage then enters the cascaded converter modules.

Therefore, the protection unit outputs the zero-fire ground of the commercial power to obtain single-phase alternating-current voltage through strong current filtering, and then the single-phase alternating-current voltage with lower power consumption is subjected to current transformation and then is output to the motor, so that the on-off time of a single power device can be reduced, and the energy loss of the power device such as an IGBT (insulated gate bipolar transistor) is reduced.

Through a large amount of experimental verifications, adopt the technical scheme of the utility model, through the topological structure who adopts single-phase full-bridge rectifier circuit of submodule piece and three-phase half-bridge contravariant cascade circuit, through sawtooth wave phase shift modulation and equalizer flow control theory, the energy conversion of having ensured each phase of converter circuit and each submodule piece is balanced, has solved the unbalanced problem of submodule piece power loss distribution, is favorable to reducing the power consumption of power components and parts.

According to the utility model discloses an embodiment still provides a motor corresponding to conversion control device. The motor may include: the variable flow control device described above.

In some synchronous compressor driving circuit designs, in order to make motor flux linkage control stable, an SPWM or SVPWM software driving algorithm is mostly adopted, but the SVPWM is too complex in a three-level and above topology, the harmonic content is high, design resources are greatly wasted, and the design is not beneficial to rapid product development and design.

In an optional implementation manner, the utility model discloses a scheme, to the well low power compressor in domestic air conditioner field, has provided a single cylinder compressor variable flow control system design scheme of novel converter structural control. Based on the control circuit of the air conditioner compressor, the topological structure of the submodule single-phase full-bridge rectification circuit and the three-phase half-bridge inversion cascade circuit is adopted, and the energy conversion balance of each phase and each submodule of the converter circuit is guaranteed through sawtooth wave phase shift modulation and equalizing ring flow control theories. The finally output three-phase alternating voltage is triggered and driven relative to the two-level IGBT, the harmonic content is low, and stable control operation of the motor can be realized. Therefore, the problem of unbalanced power loss distribution of the submodules is solved, the problem of more higher harmonic content of voltage waveform output by inversion is optimized, and the control effect of the motor is obvious.

That is to say, the utility model discloses a scheme provides a novel single-phase full-bridge rectification of modularization and the topological control system of cascading of many level half-bridge three-phase contravariant, adopts two independent sawtooth carrier wave phase shifting techniques, based on modularization circulation restraines layering balance control and RFOC closed-loop control principle, establishes inside and outside multilayer control loop and controls rectification side busbar voltage and contravariant side three-phase variable frequency voltage output respectively, realizes synchronous compression motor frequency conversion drive control.

Wherein, in the scheme of the utility model, topological structure does: modularized single-phase full-bridge rectification and modularized half-bridge inversion cascade topology structure, the number of bridge arm sub-modules is 3, and output load is a three-phase synchronous motor. The input side voltage is: after strong electrical filtering, the single-phase AC input at the rectifying side is rectified. The carrier wave and motor control mode is as follows: sawtooth carrier phase shift + rotor flux linkage directional control (i.e., RFOC control).

Optionally, the utility model discloses an in the scheme, adopt the contravariant topological structure of modularization converter to compressor drive circuit, reduced single power device's break-make time, reduced power device IGBT's energy loss. The direct-current bus steady-state output ripple at the rectification side is smooth, the output at the inversion side acts on the synchronous motor control, the requirements under the conditions of different bus voltages, output power and rotating speed can be met, and the speed regulation range is more flexible.

Optionally, the utility model discloses an in the scheme, to the rectification side circuit, adopt the many level of modularization transverter technique (being the MMC) topological structure of single-phase full-bridge. The clean and reliable single-phase alternating current formed by the commercial power after strong current filtering is subjected to modular rectification by the upper and lower bridge arms to form adjustable direct current bus voltage, so that the design of an actual product is more met, and the output and control of a rectification side are more flexible due to the cascade connection of IGBT component topology; meanwhile, the part replaces a PFC circuit, and power factor correction can be realized. The harmonic content of the output three-phase voltage is obviously reduced, the capacity of a filter is reduced, and the cost reduction effect of the controller is obvious.

Optionally, the utility model discloses an in the scheme, cascade half-bridge IGBT module contravariant topology adopts inside and outside double loop control, makes control output more nimble, can satisfy the operation of synchronous machine under different output or rotational speed condition.

Wherein, the utility model discloses a scheme can be applicable to the three-phase power output system of different grades, but in high power system such as megawatt level system, required submodule piece quantity is great. More sub-modules can effectively suppress higher harmonics, protect the system and are more suitable for being applied to an electric power system, but in a synchronous compressor system, the hardware cost is overlarge due to the fact that the number of the sub-modules is too large, the number of sampling data is more, and the calculation requirement on a system chip is higher. Meanwhile, when the low-frequency starting is operated, a boost circuit needs to be added to realize pre-starting boosting in the technology.

Additionally, the utility model discloses a scheme also can be applicable to the synchronous machine drive circuit of different power. For example: the variable-frequency speed regulation closed-loop control of the synchronous compressor can be realized through rotor flux linkage directional control (RFOC) and carrier phase shift PWM (pulse-width modulation); the advantages of air conditioner series products in the aspect of variable frequency driving can be enhanced, the performance quality and the electric energy utilization rate of the products are enhanced, and the service life of the products can be greatly prolonged due to the balanced power of the sub-modules. However, the number of modules required for controlling the high-power motor is large, and the cost of elements is high; meanwhile, the circuit topology network has more sampling data and higher requirement on DSP data arithmetic capability.

For example: the full-speed range motor driving scheme based on the MMC is suitable for low-speed operation, has good starting performance and wide speed regulation range, but the driving mode only considers direct-current side voltage inversion and mainly acts as an induction motor. That is, the MMC-based full speed range motor drive is the IM motor full speed regulation, the system flexibility is high, but the rectification side has DC voltage and the speed regulation is VF speed regulation; and in the scheme of the utility model, the rectification side is the alternating current voltage source, and the mode speed governing that electrical machinery system adopted RFOC and power speed governing control circuit.

For example: the scheme of the modularized multi-level converter four-quadrant frequency converter aims to solve the problems that capacitance and voltage fluctuation exists when an MMC operates at a low frequency, a high-frequency injection method brings large current impact and the like. However, the method is more suitable for high-voltage high-power electric energy conversion occasions, meanwhile, the low-frequency operation is between 5Hz and 50Hz, a control loop is not established, and transient change in the frequency conversion regulation process cannot be reflected. That is to say, the MMC four-quadrant converter mainly focuses on the problems of capacitance fluctuation and current surge during low-frequency operation, and adopts a rectifier module to adopt three-phase rectification and simultaneously adopts an upper bridge arm and a lower bridge arm as a full bridge and a half bridge. However, the scheme of the utility model, what adopt is single-phase full-bridge rectification-three-phase half-bridge contravariant's conversion topology, introduces the control loop such as magnetic flux vector and power of motor system simultaneously, and the non-solid is frequently, more accords with the actual speed governing control of synchronous compression motor.

For example: a full-bridge MMC type high-voltage three-phase-single-phase direct converter and a control scheme thereof are disclosed, wherein the converter comprises H bridge chain links and a filter inductor, the topology adopts star-shaped links to realize single-phase load output, but the system output is a single-phase load, mainly plays a role in power grid side rectification and is not suitable for being driven by a three-phase alternating current motor. That is to say, full-bridge MMC formula high pressure three-phase-single-phase direct converter and control scheme are three-phase modularization rectification, and the submodule piece adopts full-bridge module, and H bridge chain quantity is 6, and star type interlinkage is exported, mainly satisfies the voltage of single-phase load, is fit for the electric wire netting rectification output, but is not suitable for drive circuit.

In an optional example, the utility model discloses a scheme adopts a novel modularization to cascade the conversion topological structure, divide into single-phase full-bridge rectifier module side and three-phase half-bridge contravariant module side, inputs single-phase alternating current, outputs three-phase alternating voltage. Both parts are modular signal hierarchical control. In the scheme, the number of the upper and lower bridge arm sub-modules of the rectification and inversion module is 3.

Optionally, two independent sawtooth waves are generated by a DSP processor or a hardware analog circuit, and PWM pulse signals are respectively output to each submodule of the single-phase rectifier bridge arm and the three-phase modular inverter bridge arm by using a phase shift modulation technique and a circulation hierarchical control manner.

The two sawtooth waves which act independently respectively act on the two module units, are independent from each other and do not interfere with each other, and are convenient for subsequent phase shift processing of different modules. The DSP processor programming output or the hardware simulation circuit is adopted to realize the carrier wave mode, the DSP can be used, the peripheral circuit design resource is saved by the DSP, but the pure hardware simulation is cheaper.

Optionally, the bridge arm sub-module of the full-bridge module at the rectifying side is 4 IGBT cascade topologies, and the scheme has low output ripple waves and plays a role in power factor correction to replace a PFC structure in the original controller.

Optionally, the rectifying side adopts a single-phase closed-loop control loop taking the output direct-current bus voltage as a reference, and based on a sawtooth carrier phase-shift modulation technology, the rectifying side respectively performs balanced control on the direct-current bus voltage, the current, the bridge arm voltage and the submodule capacitor voltage, so as to realize the output of the direct-current bus voltages of different levels under the constant alternating current. Therefore, flexible output can be realized, the output is more flexible, and the conduction conditions of different modules of IGBTs can be changed to meet different direct-current voltage outputs in an adjustable range.

Optionally, the inversion side sub-module of the converter module is in a 2-IGBT cascaded half-bridge structure, and the three-phase variable-frequency voltage and current output is realized through a hierarchical control mode of outer ring voltage control, phase-to-phase balance, bridge arm inner ring current suppression and sub-module capacitor voltage balance by taking the rotating speed and output power of an active synchronous motor as reference. Therefore, the inverter sub-module adopts the cascaded half-bridge relative to the rectifier module, mainly considers that the number of three-phase output modules is large, and the half-bridge is adopted to save the cost.

Optionally, the novel modular cascaded converter outputs a synchronous compressor. The output end monitors three-phase current, rotor position and speed, meanwhile, power regulation and rotating speed reference point regulation are added to the input end respectively, and the whole new control system realizes closed-loop variable frequency control on the compressor in an RFOC mode.

The output motor terminal signal is sampled, and the load terminal signal can be obtained through a sampling resistor or a sensor. RFOC is vector control, can directly control through the motor stator signal of terminal, and control is simplified and accurate.

In an alternative embodiment, reference may be made to the examples shown in fig. 2 to fig. 8, which may be divided into two parts, i.e., a converter topology and a system internal and external modular hierarchical control strategy, to exemplarily describe a specific implementation manner of the scheme of the present invention.

In an alternative embodiment, the following exemplary description may be referred to for a description of the converter topology.

When the power supply is started, the main controller of the compressor outputs a single-phase alternating-current voltage through the zero-live wire port of the accessed commercial power through the strong-current secondary filter circuit, and meanwhile, a strong-current filter and protection circuit (such as a discharge control chip) is added into the zero-live wire port, so that the compressor is broken when the AC power exists, and a short circuit is formed when the AC power is cut off, so that rapid discharge is formed.

FIG. 2 is a schematic diagram of a control system for one embodiment of a variable flow air conditioner compressor.

As shown in fig. 2, the single-phase ac power enters a new converter control system after being output, and the system is a topology structure of modular single-phase full-bridge rectification and three-phase full-bridge inversion. The AC terminal first passes through a modular rectification circuit.

Fig. 3 is a schematic structural diagram of an embodiment of a single module on the rectifying and inverting sides of the converter.

As shown in fig. 3, a modular full-bridge topology sub-circuit in which N IGBTs are connected in series two by two and then connected in parallel is adopted, each phase of an alternating current signal is divided into an upper bridge arm and a lower bridge arm, and each bridge arm can adopt N full-bridge topology sub-modules. In the scheme, the number of IGBTs in the bridge arm sub-modules is 4, and the number of the bridge arm sub-modules (SM) is 3.

On the rectifying side, the AC power supply is boosted through an inductor to transfer energy after filtering, then the full-bridge submodule on the rectifying side is switched on and rectified, the output voltage is subjected to energy storage filtering through a sub-capacitor, and finally the direct-current bus voltage U with smaller ripples is output in a superposed mode_dc. And switching on and off rectification, specifically, pulse signals are used for switching on and off the IGBT of the submodule to drive, and rectification output after inductive energy is transferred is realized through switching on and off of the IGBT.

On the inversion side, the DC bus voltage U_dcAs the inversion input side comes from the modular multi-level rectification, the output range is flexible. DC bus voltage U_dcThree-phase alternating current U converted into control motor through modular inversion topology_A、U_B、U_C. The submodule of the modular half-bridge inverter topology adopts a topological structure that N IGBTs are connected in series two by two and then cascaded, and N is a natural number.

The multi-level voltage waveform output on the inversion side is a waveform obtained by superposing a plurality of level signals. Similar to the output sinusoidal signal, but not the standard sinusoidal signal, so harmonics are present. The more the number of levels is, the more a sine wave is approximated, the less the distortion of the output waveform is, and the less the harmonic signal is.

Similarly, the same applies to the rectification part, and the voltage level U is output by the module after the alternating current passes through a plurality of power devices_{c_j}And (4) superposing to obtain the integral direct current bus output voltage. Namely, the voltage energy of the direct current bus is a direct current constant value after multi-level current is superposed, and can be flexibly adjusted.

The specific adjustment mode can be referred to as a closed-loop control mode shown in (b) and (c) of fig. 8, which is similar to inversion in principle, and also combines carrier phase shift and equalization control, but the control target is a single-phase full-bridge module. And adjusting the multi-time superposition output state of the capacitance level of the submodule by adjusting the on-off state of the IGBT.The part being PI control, in conjunction with FIG. 8, e.g. given a reference

Which is greater than the actual U_dcThen it is necessary to raise U_dcAnd the IGBT conduction energy in the module is increased through PWM carrier phase shift adjustment and circulation balance control, so that the superposition rectification output of a plurality of capacitance levels is improved.

Fig. 4 is a schematic structural diagram of another embodiment of a single module on the rectifying and inverting sides of the converter.

As shown in FIG. 4, in this scheme, the number of IGBTs in a submodule is 2, wherein the submodule capacitor voltage is U_{c_j}The IGBT switching voltage is V_x. Simultaneously, three-phase output comes from three contravariant bridge arm, and is the same with the rectification side, and the bridge arm of every looks of this part can adopt a N half-bridge submodule piece topology the utility model discloses a quantity of bridge arm submodule piece (SM) can be 3 in the scheme.

Fig. 5 is a schematic diagram of a topological structure of a multilevel cascaded converter when an interphase bridge arm module is 6; the structure of the first part of the multilevel cascaded converter is shown in the specification, (a) the structure of the second part of the multilevel cascaded converter is shown in the specification, (b) the structure of the third part of the multilevel cascaded converter is shown in the specification, and (d) the structure of the fourth part of the multilevel cascaded converter is shown in the specification.

Wherein, the upper and lower bridge arms of the inversion side are respectively connected with an inductor (L) in series_s) The voltage-reducing circuit can be used for reducing voltage, voltage signals are output through an inductor and act on a three-phase synchronous compression motor, and a complete modularized multi-level hardware current-converting topology is shown in figure 5.

In an alternative embodiment, the following exemplary descriptions may be referred to for a system modularization hierarchical control strategy.

Fig. 6 is a schematic structural diagram of a topology overall driving control system of a cascaded converter.

The topology overall driving control system of the cascaded current transformer shown in fig. 6 can be mainly divided into a cascaded current transformer module, a sawtooth carrier phase shift modulation module and an outer loop parameter control module.

The 220V alternating voltage passes through the zero-live wire strong electric filtering protection circuit to output single-phase alternating voltage. The single phase voltage then enters the cascaded converter modules. For a specific control process, see the following exemplary description.

Firstly, a cascade conversion module of the system adopts single-phase full-bridge rectification and three-phase half-bridge inversion, at least an inversion part adopts IGBT modular cascade, the specific topology can refer to the examples shown in figures 3 and 4, L C filter circuits are adopted in the middle for linkage, the DC fluctuation of an output direct-current bus is ensured to be smaller, and the part can realize three-phase conversion output with smaller harmonic wave and higher power factor.

For example: the rectification part can adopt a single-phase IGBT module, and can also adopt the cascade connection of more than two-phase IGBT modules. And the inverter part needs to adopt more than two-phase IGBT module cascade, such as preferably three-phase IGBT module cascade.

Secondly, sampling a current signal I output by three phases in the link of outer loop parameter control_A、I_B、I_CThe ac component is converted to a dc component in dq quadrants by park and clark conversion. And simultaneously sampling signals of torque, position, angular speed and the like of the motor stator load. I forming q quadrant by PI operation with external reference given value_qThe component is given a value. I of d quadrant in the system_dThe component setpoint is initially 0. When relevant direct current components (position, angular velocity, torque power and the like) are used as output reference components to be injected into a system, components in dq quadrants are inversely transformed and converted into alternating current components which can act on a motor system, and the output of the alternating current components is mainly three-phase reference voltage.

Finally, sampling upper and lower bridge arm capacitance voltage signals U on each submodule_{c_pj(n)}、U_{c_nj(n)}(ii) a And simultaneously, the voltage signals obtained in the last step are injected into a modulation system together. The modulation system adopts sawtooth carrier phase shift modulation, and forms PWM fundamental waves on each submodule after PI iterative operation is carried out on submodule capacitor voltage and three-phase voltage signals. Then the fundamental waves on the upper and lower bridge arms are compared with the phase-shifted sawtooth carrier waves to form a plurality of PWM output signals on a rectifier module and an inverter module, and each IGBT in the topology is controlledThe gate signal of (2).

For a specific hierarchical control strategy of carrier phase shift modulation, refer to fig. 6 and its related description. It should be noted that the upper and lower bridge arms in the rectification and inversion parts cannot be turned on simultaneously, so that the fundamental wave signal needs to be inverted, then the phase of each submodule in the full bridge with the carrier phase shift angle is shifted by 2 pi/N, and the half bridge is pi/N.

That is to say, the structural improvement of the topology overall driving control system of the cascaded converter mainly includes the following points:

the first point is that the rectification inversion is a modularized multi-level topology, the rectification is a single-phase full-bridge topology, the inversion is a three-phase half-bridge topology, and the upper and lower bridge arms of each phase are connected in series by 3 sub-modules (N is 3).

The second point and the outer ring control are motor RFOC closed-loop control, different from direct output of three-phase voltage, the reference point of the system is mainly stator rotating speed or torque, and the control mode can be diversified by combining with actual requirements.

And the modulation system adopts two independent control loops to respectively carry out multipath output on the rectifying side and the inverting side, and the PWM mode combining the full bridge and the half bridge enables the system to be controlled more flexibly. Meanwhile, different from most triangular carrier converters, the scheme adopts sawtooth carriers, and the difference of output waveforms of the two schemes is found to be small through data comparison, so that the scheme can be used as a new standby scheme.

In the example shown in fig. 6, the overall system control method may be divided into rectification-side dc modular control and inverter-side motor variable-frequency drive control. Both adopt a sawtooth carrier phase-shift modulation technology and layered circulation balance control, and are characterized in that a rectifying side takes DC bus voltage as an output reference signal, and an inverting side takes actual variable frequency rotating speed or PQ control as reference point closed-loop control.

FIG. 7 is a block diagram of an embodiment of a hierarchical control of drive system modules; the structure schematic diagram of the MMC sub-module energy balance control ring is shown in the specification, wherein (a) is a structure schematic diagram of capacitor voltage layered balance control, (b) is a structure schematic diagram of a phase balance control ring, (c) is a structure schematic diagram of an upper bridge arm balance control ring and a lower bridge arm balance control ring, (d) is a structure schematic diagram of a circulation current suppression control ring, and (e) is a structure schematic diagram of an MMC sub-module energy balance control ring. Fig. 8 is a schematic structural diagram of an embodiment of a control strategy loop on the modular converter inversion side and the rectification side, where (a) is a schematic structural diagram of RFOC modular converter inversion control of a synchronous motor, (b) is a schematic structural diagram of PI control on the rectification side, and (c) is a schematic structural diagram of closed-loop equalization control on the rectification side.

With reference to fig. 6, for the examples shown in fig. 7 and 8, the topology of the rectifier switching device adopts a sawtooth carrier phase shift modulation technique as a PWM modulation signal, and under the action of 220V AC voltage, the interphase energy balance, the total voltage of each phase bridge arm, and the capacitor voltage of each sub-module are respectively detected, and the amplitude of the output voltage at the rectifier side can be controlled along with the duty ratio of the on-state of the switch (SMn) of the rectifier sub-module.

Fig. 8 is a control strategy loop.

Fig. 8 (a) is an outer loop of the RFOC inverter control, which is a detailed development of fig. 5, and the coefficients are expanded in detail, and the following formula is combined to establish the outer loop controlled by the rotation speed, the torque or the power, and the specific analysis of the mathematical model is described in detail in step (13). The outer ring is mainly used for realizing the first-layer control in subsequent hierarchical control, obtaining three-phase voltage output components under the condition of given reference components, and facilitating the subsequent carrier phase shift for calculating PWM signals.

In fig. 8 (b) and fig. 8 (c), the PI closed-loop control circuit on the rectification side obtains the dc bus reference voltage U by using the dc output power or the dc bus voltage as a reference point and calculating with the actually sampled dc bus current_refThen, a PWM driving signal for adjusting the full-bridge sub-module is obtained through a saw-tooth carrier signal comparator, and the output of the dc bus is controlled, where (b) in fig. 8 is rectifier-side PI control, and (c) in fig. 8 is a specific developed loop after (b) in fig. 8 is combined with module voltage equalization control.

Wherein, in the scheme of the utility model, the sawtooth phase-shift carrier wave is adopted to control the output of the full-bridge PWM; the outer ring establishes a control loop through the output voltage and power of the rectifying side, and voltage requirements of different levels of the inverting side in a requirement interval are met; the double-loop control independently acts on the outer ring of the rectification inverter, but the inner layers are controlled in a layered mode, and the voltage balance of the module capacitor is met.

In the example shown in fig. 8 (c), the rated dc bus output voltage 311V is used as the reference voltage

The actual output voltage of the direct current bus is U_dc. In a control loop, currents input into an upper bridge arm and a lower bridge arm in a single phase are detected, half of the current is obtained after summation to obtain interphase circulating current i_cjIs related to the DC bus current i_dcAfter operation, the direct current bus feedback reference voltage and U are obtained through PI control_dcObtaining the reference value of each voltage of the submodules at intervals after operation, adding the voltage components of the capacitors of the submodules after inversion to form fundamental wave waveforms of PWM modulation, the number of the fundamental wave waveforms is 2N, and converting U into U_dcAs a pre-adjustment.

As shown in FIG. 8 (b) and FIG. 6, the whole DC output side forms a main feedback loop of an outer loop, and the AC voltage U at both ends of the rectified side is detected and sampled_acD.c. voltage U_dcAnd system power. Performing PI operation on the difference value of the actual rectified voltage and the reference voltage by adopting bus DC control or power PQ control to obtain the reference current of the dq quadrant after rectification

Obtaining the reference current vector of the upper and lower bridge arms of each phase through iterative operation

The current vector is differed with the actual value of the current of the direct current bus to form the reference current of the direct current bus

Obtaining variable voltage by PI operation of the obtained current, and adding actual output voltage component U_dcAnd obtaining fundamental wave output reference voltage. Fig. 8 (c) is an extension of the drive signal adjustment logic of fig. 8 (b). In fig. 8 (c), the voltage equalizing value U per SM_{c_ji}And the actual value

Obtaining the fundamental wave reference voltage of each phase submodule through voltage balance control

And then, carrying out sawtooth wave phase-shift carrier PWM operation to obtain a PWM pulse signal corresponding to the full-bridge sub-module switch, and outputting direct-current voltage. Finally by changing U_dcAnd power, and the closed-loop control of the adjustable direct current voltage or the adjustable power is realized.

The utility model discloses an in the scheme, to rectification feedback loop, control mode adopts the mode of voltage energy layering transmission. The method mainly comprises inner and outer ring control, wherein the inner ring adopts phase voltage balance control, bridge arm voltage balance control and submodule capacitor voltage balance. The feedback reference signal is power or DC bus direct-current voltage U_dc。

In the scheme of the utility model, the rectification side carrier phase shift adopts N sawtooth waves to shift phase pi/N in order to obtain the best harmonic elimination characteristic, namely the range of the carrier phase shift angle is 0-pi/2N. In the modulation system, because the number of the IGBTs in the module is 4, each phase of bridge arm has two voltage reference signals, the obtained fundamental wave waveforms need to be inverted and respectively correspond to the left half bridge arm and the right half bridge arm of the same submodule, and a reference voltage formula of the left half side and the right half side of the upper bridge arm and the lower bridge arm is obtained

As follows. Wherein p represents an upper bridge arm; n represents a lower bridge arm; u shape_SMc＝U_dcthe/N is the capacitance voltage of a given submodule; m is a modulation ratio).

Where ω denotes a three-phase alternating-current voltage output angular frequency (ω ═ 2 pi f); theta_jIs the initial quadrant angle of j phase (j ═ a, B, C).

The utility model discloses an in the scheme, the direct current bus voltage of modularization rectification side output gets into the many level inverter circuit of modularization after the electric capacity filters. The inverter circuit adopts a half-bridge sub-module structure with double IGBTs connected in parallel, and the overall control mode can be as shown in an example in (a) in fig. 6 and 8. The rotating speed or power is adopted as the feedback regulation of the rotor flux linkage directional control (RFOC) of the whole motor system, so that the module outputs a three-phase alternating current signal.

The utility model discloses an in the scheme, entire system's contravariant topological control also adopts hierarchical control's structure. As with the architecture described in fig. 7, the control loops of the various levels are analyzed in detail here.

First, the first stage is the overall control of a variable flow feedback system, the outer loop control is the motor rotation speed control or the output power control, and the inner loop is the current control of a dq0 rotating coordinate system. In connection with the examples shown in fig. 6 and fig. 8 (a), the basic idea of the inner loop control is to sample the three-phase output side voltage current, position and angular velocity signals. Subjecting the abc current signal to Clark conversion and park conversion to obtain a direct current component signal (i)_q，i_d). Simultaneously the motor outputs an angular velocity signal omega_eAnd the position angle signal theta is subjected to PI conversion to obtain a rotation speed signal and a reference rotation speed omega^*Comparing them to form a rotation speed difference to obtain a torque signal T^*And obtaining a current reference signal of q quadrant through PI conversion

The given current reference signal for the d-quadrant is initially

At the same time, the converted DC component signal (i) is combined_q，i_d) Do it

Calculating to obtain a voltage variable signal under the dq coordinate system

After Clark inverse transformation and park inverse transformation, the final three-phase AC output reference voltage of the first stage is obtained

In the first stage control, the conversion formula of the partial signal is as follows:

λ_q＝L_q*i_q；λ_d＝L_d*i_d+λ_f；

wherein P is the converter output power, P_devAnd T_devFor the power and speed, lambda, output by the converter to the motor_fFor the stator flux linkage (which can be determined from the stator inductance and the induced current), λ_d，λ_qIs determined for dq quadrantSub-flux linkage component, L_d，L_qIs an inductance component, U, in the motor dq coordinate system_sd，U_sqFor the voltage component of the three-phase AC output voltage in the dq quadrant, P^*For reference to the power variable signal, T^*Is a torque reference variable signal of the synchronous motor without the salient, p is the stator magnetic pole logarithm, omega_eIs the motor rotation angular velocity.

Further, the second phase of the modular inversion is interphase balance control. The basic idea of the example shown in fig. 7 is to give the outer rings of the phases a given voltage as the dc bus voltage U_dcThe feedback signal is half of the sum of the capacitor voltages of all sub-modules. Comparing the two, and obtaining a given phase circulation direct current component I after PI operation_cj(j represents any phase of A, B and C).

Further, the third stage is bridge arm balance control. As shown in FIG. 7, the given reference value is the DC component of the sum of the upper and lower arm capacitor voltages of each phase: (

And

) After the difference is made, PI operation is carried out, and then a reference phase signal of the alternating voltage is added to obtain a reference phase circulation alternating current component i_{cj_ac}. Adding the two signals to obtain a circulating current given reference signal, comparing the circulating current given reference signal with an actual circulating current signal, and outputting the circulating current given reference signal and the actual circulating current signal to obtain an inner ring voltage direct current reference signal through PI-resonant regulation

Respectively adding or subtracting the AC component in the reference voltage

Obtaining reference voltage signals of upper and lower bridge arms

And

further, the fourth stage is sub-module capacitor voltage balancing. Each submodule of each bridge arm corresponds to an independent control ring. The reference voltage is one N times of the capacitor voltage of the bridge arm. Taking the capacitor voltage of each module as feedback, adding the current direction of the phase bridge arm after proportional adjustment, and summing with one N times of the bridge arm voltage to obtain the voltage reference signal of each submodule of the upper and lower bridge arms (a

And

). Finally, the signals are sent to carrier phase shift modulation to generate respective PWM pulse signals.

And the half-bridge submodule of the inverter module also adopts carrier phase shift modulation. In the utility model, the inversion topology carrier phase shift adopts N sawtooth waves to sequentially shift 2 pi/N phase to obtain the best harmonic elimination characteristic, namely the range of the carrier phase shift angle is 0-pi/N. In the modulation system, the voltage reference signals of each submodule of an upper bridge arm and a lower bridge arm are as follows:

and the rectification module and the sub-modules in the inversion module are controlled in a carrier phase-shifting layered mode, and single-phase alternating current is rectified and then inverted to output alternating current signals capable of enabling the three-phase motor to carry out frequency conversion. The whole external control loop of the two parts, direct current bus voltage closed loop feedback control and RFOC motor rotating speed control respectively and independently control the respective modules, so that the regulation capability of the whole converter system is more flexible.

In an optional concrete example, the utility model discloses a scheme is applicable to the compressor drive circuit of different power grades, because modular structure control, the improvement of circuit topology is comparatively nimble with the transform, and output voltage electric current harmonic content is few, and electric energy quality is high. The utility model discloses a scheme has adopted comparatively complicated topological structure in the conversion structure, can replace the PFC module among the relevant air condition compressor control system, can the wide application in high-power air conditioner conversion system, is favorable to promoting the competitiveness of product. The utility model discloses a scheme modified frequency conversion current transformation mode can analogically derive and use motor control field and new forms of energy contravariant field.

Since the processes and functions implemented by the motor of this embodiment substantially correspond to the embodiments, principles, and examples of the apparatus shown in fig. 1, the descriptions of this embodiment are not detailed, and refer to the related descriptions in the embodiments, which are not described herein.

Through a large amount of tests verification, adopt the technical scheme of the utility model, through the topological structure that adopts single-phase full-bridge rectifier circuit of submodule piece and three-phase half-bridge contravariant cascade circuit, through sawtooth wave phase-shift modulation and equalizer current control theory, the three-phase alternating voltage of final output triggers the drive for two level IGBT, and harmonic content is less, can realize the smooth control operation of motor. Therefore, the problem that the higher harmonic content of the voltage waveform output by inversion is high is solved, and the control effect of the motor is obvious.

According to an embodiment of the present invention, there is also provided a method for controlling a current transformation of a motor corresponding to the motor, as shown in fig. 9, which is a schematic flow diagram of an embodiment of the method of the present invention. The variable current control method of the motor can comprise the following steps: step S110 and step S120.

In step S110, after the single-phase ac power is converted by the converting unit, a three-phase ac voltage is output to the electric device. An electrical device may include: an electric motor such as an air conditioning compressor. The variable flow processing may include: rectification processing, filtering processing and inversion processing.

In an alternative example, the converter unit may include a modular single-phase rectification module, a filtering module, and a modular three-phase inverter module, the modular single-phase rectification module may be a single-phase modular full-bridge rectification circuit, the filtering module may be an L C filtering circuit, the modular three-phase inverter module may be a three-phase modular half-bridge inverter circuit, an output terminal of the modular single-phase rectification module is connected to an input terminal of the modular three-phase inverter module, and the filtering module is disposed between the modular single-phase rectification module and the modular three-phase inverter module.

Referring to fig. 10, a schematic flow chart of an embodiment of the method of the present invention for converting single-phase ac power further illustrates a specific process of converting single-phase ac power in step S110, which may include: step S210 to step S230.

Step S210, rectifying single-phase alternating current such as single-phase AC through a modularized single-phase rectifying module, and then outputting direct-current bus voltage.

Step S220, a filtering module is used to filter the dc bus voltage after the single-phase ac is rectified, so as to obtain the filtered dc bus voltage.

Step S230, inverting the filtered dc bus voltage by the modular three-phase inversion module to output a three-phase ac power, specifically, a three-phase ac power, which can be used as a driving voltage of a motor such as a compressor.

For example: the inverter topology structure of the modular converter is adopted for the compressor driving circuit, the on-off time of a single power device is reduced, and the energy loss of the IGBT of the power device is reduced. The direct current bus steady state output ripple at the rectification side is smooth, the output at the inversion side can be used for controlling the synchronous motor, the requirements under the conditions of different bus voltages, output power and rotating speed can be met, and the speed regulation range is more flexible.

For example, the cascade conversion module of the system adopts single-phase full-bridge rectification and three-phase half-bridge inversion, and parts of the cascade conversion module adopt IGBT modular cascade, the middle part of the cascade conversion module adopts L C filter circuit link, so that the DC fluctuation of an output direct-current bus is ensured to be smaller, and the part of the cascade conversion module can realize three-phase variable-current output with smaller harmonic wave and higher power factor.

Therefore, single-phase alternating current is subjected to current transformation processing through the modularized single-phase rectification module, the filtering module and the modularized three-phase inversion module, and the modularized single-phase rectification module and the modularized three-phase inversion module are adopted, so that the energy loss of a power device can be reduced due to the fact that the on-off time of the single power device is shortened. The direct current bus on the rectifying side has smooth steady-state output ripples, so that the harmonic content of three-phase alternating current voltage output by the inverting side is low, the voltage waveform of inverting output is optimized, and stable control operation of electric equipment such as a motor is facilitated.

In step S120, the control unit obtains the current transformation parameters of the current transformation unit and the operation parameters of the motor, and performs phase shift modulation and loop current layered control on the current transformation unit according to the current transformation parameters and the operation parameters, thereby implementing layered closed-loop control between the current transformation unit and the motor.

For example: a modular single-phase full-bridge rectification and multilevel half-bridge three-phase inversion cascade current transformation topology control system adopts two independent sawtooth carrier phase shifting technologies, and establishes an inner multilayer control loop and an outer multilayer control loop to respectively control the output of a rectification side bus voltage and an inversion side three-phase variable frequency voltage based on a modular circulation suppression hierarchical balance control and RFOC closed-loop control principle, so as to realize the variable frequency drive control of a synchronous compression motor.

For example, aiming at a low-power compressor in the field of household air conditioners, a design scheme of a single-cylinder compressor variable flow control system controlled by a novel converter structure is provided. Based on the control circuit of the air conditioner compressor, the topological structure of the submodule single-phase full-bridge rectification circuit and the three-phase half-bridge inversion cascade circuit is adopted, and the energy conversion balance of each phase and each submodule of the converter circuit is guaranteed through sawtooth wave phase shift modulation and equalizing ring flow control theories. The finally output three-phase alternating voltage is triggered and driven relative to the two-level IGBT, the harmonic content is low, and stable control operation of the motor can be realized. Therefore, the problem of unbalanced power loss distribution of the submodules is solved, the problem of more higher harmonic content of voltage waveform output by inversion is optimized, and the control effect of the motor is obvious.

Therefore, through the current transformation unit and the control unit, current transformation processing is carried out based on the single-phase intersection current point, and phase shift modulation and circulation control are carried out on the current transformation unit, so that the problem of large power consumption of a power device element in a topological mode of adopting two-level inversion can be solved, namely the problem of unbalanced power loss distribution of sub-modules is solved, and the power consumption of the power device element is reduced; the problem that the higher harmonic content of the voltage waveform output by inversion is high can be solved, the harmonic content is reduced, and stable control operation of electric equipment such as a motor is facilitated.

In an alternative example, the control unit may include: the phase shift modulation module, such as a sawtooth wave phase shift modulation module, may be connected to the single-phase modular full-bridge rectifier circuit and the three-phase modular half-bridge inverter circuit in the converter unit, respectively. In step S120, the phase shift modulation and the loop current hierarchical control on the converter unit by the control unit may include: through the phase shift modulation module, two independent sawtooth waves are utilized, the phase shift modulation technology and the circulation hierarchical control mode are adopted, pulse signals are respectively output to the rectification processing side and the inversion processing side in the current transformation unit, for example, pulse signals, preferably PWM pulse signals, are respectively output to the modular single-phase rectification module and the modular three-phase inversion module in the current transformation unit, and the rectification processing side and the inversion processing side in the current transformation unit are driven through the pulse signals.

For example: two independent sawtooth waves are generated by a DSP (digital signal processor) or a hardware analog circuit, and PWM (pulse width modulation) pulse signals are respectively output to each submodule of a single-phase rectifier bridge arm and a three-phase modular inverter bridge arm by adopting a phase shift modulation technology and a circulation hierarchical control mode.

For example: the modulation system adopts two independent control loops to respectively carry out multipath output on the rectifying side and the inverting side, and the PWM mode combining the full bridge and the half bridge enables the system to be controlled more flexibly. The overall control mode of the system can be divided into rectification side direct current modular control and inversion side motor variable frequency drive control. Both adopt a sawtooth carrier phase-shift modulation technology and layered circulation balance control, and are characterized in that a rectifying side takes DC bus voltage as an output reference signal, and an inverting side takes actual variable frequency rotating speed or PQ control as reference point closed-loop control.

Therefore, through the phase shift modulation module, pulse signals are respectively output to the rectification processing side and the inversion processing side based on two independent sawtooth waves through a phase shift modulation technology and a circulation layered control mode, the rectification processing side and the inversion processing side can be independently driven, and the reliability of driving can be guaranteed.

Optionally, the control unit may further include: and the rectification side sampling module, such as a rectification side alternating current and direct current voltage sampling module, a sub-module capacitance and voltage sampling module and the like. In step S120, the phase shift modulation and the loop current hierarchical control are performed on the converter unit by the control unit, and the method may further include: and controlling the process of the pulse signal of the current transformation unit according to the rectification side.

Referring to fig. 11, a flow chart of an embodiment of the method of the present invention for controlling the converter unit according to the rectification side according to the pulse signal of the converter unit according to the rectification side is further described, which may include: step S310 and step S320.

Step S310, a direct current bus signal at the rectification processing side in the converter unit, a bridge arm voltage of each bridge arm (i.e., a bridge arm voltage of each bridge arm in the single-phase rectification upper bridge arm and/or the single-phase rectification lower bridge arm), and/or a capacitance voltage of each single-phase rectification submodule (i.e., a single-phase rectification submodule in each bridge arm) are collected through the rectification side sampling module. The dc bus signal may include a dc bus voltage, a dc bus current, and the like.

And step S320, through the phase shift modulation module and a single-phase closed-loop control loop taking the direct-current bus voltage output by the rectification side as a reference, according to the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule, based on a sawtooth carrier phase shift modulation technology, adjusting the pulse signal at the rectification processing side in the current transformation unit, and realizing the balance control of the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule.

For example: the rectifying side adopts a single-phase closed-loop control loop taking the output direct-current bus voltage as a reference, and based on a sawtooth carrier phase-shift modulation technology, the direct-current bus voltage, the current, the bridge arm voltage and the submodule capacitor voltage are respectively subjected to balanced control, so that the direct-current bus voltage output of different grades under constant alternating current is realized.

For example: the rectification switch device topology adopts a sawtooth carrier phase shift modulation technology as a PWM modulation signal, under the action of 220VAC voltage, the interphase energy balance, the total voltage of each phase bridge arm and the capacitor voltage of each submodule are respectively detected, and the amplitude of the output voltage of the rectification side can be controlled along with the duty ratio of the conduction of a rectification submodule switch (SMn). For example, the PI closed-loop control circuit at the rectifying side obtains the DC bus reference voltage U after the calculation with the DC bus current sampled actually by taking the DC output power or the DC bus voltage as a reference point_refAnd then, a PWM driving signal which can be used for adjusting the full-bridge submodule is obtained through a sawtooth carrier signal comparator, and the output of a direct current bus is controlled.

For the rectification feedback loop, the control mode adopts a voltage energy layered transmission mode. The method mainly comprises inner and outer ring control, wherein the inner ring adopts phase voltage balance control, bridge arm voltage balance control, sub-module capacitor voltage balance, and feedback reference signal is power or DC bus direct current voltage U_dc. The carrier phase shift at the rectification side adopts N sawtooth waves to sequentially shift the phase by pi/N so as to obtain the optimal harmonic elimination characteristic, namely the range of the carrier phase shift angle is 0-pi/2N.

Therefore, through a single-phase closed-loop control loop taking the output direct-current bus voltage as a reference on a rectification side, based on a sawtooth carrier phase-shift modulation technology, direct-current bus voltage, current, bridge arm voltage and submodule capacitor voltage are respectively subjected to balanced control, direct-current bus voltage output of different levels under constant alternating current is realized, and flexible adjustment of the output direct-current bus voltage can be realized.

Optionally, the control unit may further include: and the inverter side sampling module, such as an inverter side three-phase current and voltage sampling module, a sub-module capacitor and voltage sampling module and the like. In step S120, the phase shift modulation and the loop current hierarchical control are performed on the converter unit by the control unit, and the method may further include: and controlling the pulse signal process of the current transformation unit according to the inversion side.

Referring to fig. 12, a schematic flow chart of an embodiment of the method of the present invention for controlling the converter unit according to the inverter side according to the pulse signal of the converter unit according to the inverter side is further described, which may include: step S410 and step S420.

Step S410, a three-phase electrical signal at an inversion processing side in the converter unit, an inner ring current of a bridge arm of each bridge arm (i.e., an inner ring current of each bridge arm in the upper and/or lower three-phase inversion bridge arms), and/or a capacitive voltage of each three-phase inversion submodule (i.e., a three-phase inversion submodule in each bridge arm) are collected by the inversion side sampling module. Wherein, three-phase electric signal can include: three-phase voltage signals, three-phase current signals, and the like.

And step S420, regulating a pulse signal at the inversion processing side in the current transformation unit through a closed-loop control loop which takes the rotating speed and the output power of the motor driven by the three-phase alternating current output by the inversion processing side as reference through the phase-shifting modulation module and according to the three-phase electric signal at the inversion processing side, the bridge arm inner ring current of each bridge arm and/or the capacitance voltage of each three-phase inversion submodule, and realizing the layered control of the outer ring control and the interphase balance of the three-phase electric signal at the inversion processing side, the bridge arm inner ring current suppression of each bridge arm and/or the capacitance voltage balance of each three-phase inversion submodule.

For example: the inversion side sub-module of the current transformation module is of a 2 IGBT cascade half-bridge structure, the rotation speed and the output power of an acting synchronous motor are taken as reference, and three-phase variable frequency voltage and current output is realized through a layered control mode of outer ring voltage control, phase-to-phase balance, bridge arm inner ring current suppression and sub-module capacitor voltage balance. Such as a sawtooth phase-shifted carrier wave to control the full-bridge PWM output. The outer ring establishes a control loop through the output voltage and power of the rectifying side, and voltage requirements of the inverting side in different grades in a requirement interval are met. The double-loop control can independently act on a rectification inversion outer loop, but the inner layers are controlled in a layered mode, and the voltage balance of the module capacitor is met.

The direct-current bus voltage output by the modularized rectifying side enters the modularized multi-level inverter circuit after being filtered by the capacitor. The inverter circuit adopts a half-bridge submodule structure with double IGBTs connected in parallel, and adopts the rotating speed or power as the feedback regulation of the rotor flux linkage directional control (RFOC) of the whole motor system, so that the module outputs a three-phase alternating current signal. The first stage is the overall control of a variable flow feedback system, the outer ring control is the motor rotating speed control or the output power control, and the inner ring is the current control of a dq0 rotating coordinate system. The second stage of the modular inversion is interphase balance control. The third stage is bridge arm balance control. And in the fourth stage, the capacitor voltage of the submodules is balanced, each submodule of each bridge arm corresponds to an independent control ring, and the reference voltage of each control ring is one N times of the capacitor voltage of the bridge arm where the control ring is located.

For example: in the step of outer ring parameter control, the current signal I output by three phases is sampled_A、I_B、I_CThe ac component is converted to a dc component in dq quadrants by park and clark conversion. And simultaneously sampling signals of torque, position, angular speed and the like of the motor stator load. I forming q quadrant by PI operation with external reference given value_qThe component is given a value. I of d quadrant in the system_dThe component setpoint is initially 0. When relevant direct current components (position, angular velocity, torque power and the like) are used as output reference components to be injected into a system, components in dq quadrants are inversely transformed and converted into alternating current components which can act on a motor system, and the output of the alternating current components is mainly three-phase reference voltage.

For example: sampling upper and lower bridge arm capacitance voltage signal U on each submodule_{c_pj(n)}、U_{c_nj(n)}. And simultaneously, the voltage signals obtained in the last step are injected into a modulation system together. The modulation system adopts sawtooth carrier phase shift modulation, and forms PWM fundamental waves on each submodule after PI iterative operation is carried out on submodule capacitor voltage and three-phase voltage signals. Then the fundamental waves on the upper and lower bridge arms are compared with the phase-shifted sawtooth carrier waves for operation to form a plurality of paths of PWM output signals on the rectifier module and the inverter module, and a gate signal on each IGBT in the topology is controlled.

Therefore, through a single-phase closed-loop control circuit taking the output direct-current bus voltage as a reference on a rectification side, based on a sawtooth carrier phase-shifting modulation technology, the outer ring control and the layered control of phase-to-phase balance, bridge arm inner ring current suppression and capacitance voltage balance of three-phase electric signals are respectively realized, and the flexible adjustment of three-phase variable-frequency voltage and current output can be realized.

Optionally, the control unit may further include: and the load side sampling module is used for sampling the position and the speed of the motor. In step S120, the phase shift modulation and the loop current hierarchical control are performed on the converter unit by the control unit, and the method may further include: and controlling the process of the pulse signal of the current transformation unit according to the load side.

Referring to fig. 13, a flow chart of an embodiment of the method of the present invention for controlling the converter unit according to the load side according to the pulse signal of the converter unit will be further described, which may include: step S510 and step S520.

Step S510, a load side sampling module is used to collect three-phase current, rotor position, and/or rotor speed of the output side motor of the converter unit.

And step S520, regulating pulse signals at the rectification processing side and/or the inversion processing side in the converter unit through a closed-loop control circuit which takes the rotating speed and the output power of the motor driven by the three-phase alternating current output by the inversion processing side as reference through the phase-shifting modulation module according to the three-phase current, the rotor position and/or the rotor speed of the motor, so as to realize the closed-loop frequency conversion control of the motor at the output side of the converter unit.

For example: the modular cascade converter outputs and acts on the synchronous compressor. The output end monitors three-phase current, rotor position and speed, meanwhile, power regulation and rotating speed reference point regulation are added to the input end respectively, and the whole new control system realizes closed-loop variable frequency control on the compressor in an RFOC mode.

For example: and the rectification module and the sub-modules in the inversion module are controlled in a carrier phase-shifting layered mode, and single-phase alternating current is rectified and then inverted to output alternating current signals capable of enabling the three-phase motor to carry out frequency conversion. The whole external control loop of the two parts, direct current bus voltage closed loop feedback control and RFOC motor rotating speed control respectively and independently control the respective modules, so that the regulation capability of the whole converter system is more flexible.

The specific hierarchical control strategy of the carrier phase shift modulation is that upper and lower bridge arms of the rectification and inversion parts cannot be simultaneously switched on, so that the fundamental wave signal needs to be inverted, then the carrier phase shift angle full bridge shifts the phase of each submodule by 2 pi/N, and the half bridge is pi/N. The outer loop control is motor RFOC closed-loop control, is different from direct output three-phase voltage, and the reference point of the system is mainly stator rotating speed or torque, and the control mode can be diversified by combining with actual requirements.

Therefore, by monitoring the three-phase current at the output side of the converter unit, the position and the speed of the motor yoke rotor and the like, and simultaneously adding power regulation and rotating speed reference point regulation to the input end respectively, the closed-loop variable frequency control of the compressor can be realized, and the operation stability of the motor can be further ensured.

In an alternative embodiment, the method may further include: and a protection unit. The protection unit, such as a strong electric filtering and protection circuit, can be arranged between an alternating current power supply, such as a commercial power zero-fire ground line 220V AC, and a current transformation unit, such as a cascade current transformation module.

Referring to the example shown in fig. 4, the 220V AC line of the zero-fire ground line of the utility power supply is a zero-fire ground line (i.e., N, L, PE), and then the stable and clean single-phase AC power is output through the strong electric filtering and protecting module (i.e., two lines L and N), so that the clean and stable state refers to reduction of interference (harmonic waves, etc.) in the external power grid through secondary filtering.

For example: when a power supply is started, a zero-fire ground wire port connected to a mains supply outputs a single-phase alternating-current voltage through a strong-current secondary filter circuit, meanwhile, a strong-current filter and protection circuit (such as a discharge control chip) is added to the zero-fire wire output port, the circuit is broken when the AC power exists, a short circuit is formed when the AC power is disconnected, rapid discharge is formed, and residual voltage of a large capacitance device in a system is released.

For example: the 220V alternating voltage passes through the zero-live wire strong electric filtering protection circuit to output single-phase alternating voltage. The single phase voltage then enters the cascaded converter modules.

Therefore, the protection unit outputs the zero-fire ground of the commercial power to obtain single-phase alternating-current voltage through strong current filtering, and then the single-phase alternating-current voltage with lower power consumption is subjected to current transformation and then is output to the motor, so that the on-off time of a single power device can be reduced, and the energy loss of the power device such as an IGBT (insulated gate bipolar transistor) is reduced.

Since the processing and functions implemented by the method of this embodiment substantially correspond to the embodiments, principles and examples of the motor, reference may be made to the related descriptions in the foregoing embodiments without being detailed in the description of this embodiment, which is not described herein.

Through a large number of tests, the technical scheme of the embodiment is adopted, two independent sawtooth carrier phase shifting technologies are adopted, based on the modular circulation suppression hierarchical balance control and the RFOC closed-loop control principle, an inner multi-layer control loop and an outer multi-layer control loop are established to respectively control the output of a rectification side bus voltage and an inversion side three-phase variable frequency voltage, the variable frequency drive control of the synchronous compression motor is realized, the energy loss of a power device IGBT is reduced, and the harmonic content of the output three-phase voltage is obviously reduced.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. A variable flow control device, comprising: a current transformation unit and a control unit; wherein the content of the first and second substances,

the current transformation unit is used for outputting three-phase alternating current to the motor after the single-phase alternating current is subjected to current transformation processing; wherein, the variable flow treatment comprises: rectifying, filtering and inverting;

and the control unit is used for acquiring the variable flow parameters of the variable flow unit and the operating parameters of the motor, and performing phase shift modulation and circulation layered control on the variable flow unit according to the variable flow parameters and the operating parameters to realize layered closed-loop control between the variable flow unit and the motor.

2. The variable flow control device according to claim 1, wherein the variable flow unit comprises: the device comprises a modular single-phase rectification module, a filtering module and a modular three-phase inversion module; wherein the content of the first and second substances,

the modular single-phase rectification module is used for outputting direct-current bus voltage after rectifying single-phase alternating current;

the filtering module is used for filtering the direct current bus voltage after the single-phase alternating current is rectified so as to obtain the direct current bus voltage after filtering;

and the modular three-phase inversion module is used for performing inversion processing on the filtered direct-current bus voltage and outputting three-phase alternating current.

3. The variable flow control device of claim 2, wherein the modular single phase rectifier module comprises: the single-phase rectification bridge comprises a boosting module, a single-phase rectification upper bridge arm and a single-phase rectification lower bridge arm; wherein the content of the first and second substances,

the boost module is arranged between the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm, and is used for boosting the single-phase alternating current and then respectively transmitting the single-phase alternating current to the single-phase rectification upper bridge arm and the single-phase rectification lower bridge arm for rectification;

each of the single-phase rectification upper bridge arm and/or the single-phase rectification lower bridge arm comprises: a single-phase rectifier sub-module; the number of the single-phase rectifier sub-modules is a first set value, and the single-phase rectifier sub-modules with the first set value are arranged in a cascade mode; each single-phase rectifier sub-module comprising: the single-phase full-bridge rectifier submodule and/or the single-phase half-bridge rectifier submodule.

4. The variable flow control device of claim 2, wherein the modular three-phase inversion module comprises: the voltage reduction module, the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm; wherein the content of the first and second substances,

the voltage reduction module is arranged between the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm and is used for carrying out voltage reduction treatment on the three-phase alternating current subjected to the inversion treatment by the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm and then outputting the three-phase alternating current to the motor;

each of the three-phase inversion upper bridge arm and the three-phase inversion lower bridge arm comprises: a three-phase inversion submodule; the number of the three-phase inversion sub-modules is a second set value, and the three-phase inversion sub-modules with the second set value are arranged in a cascade mode; each three-phase inversion submodule comprises: and the three-phase full-bridge inversion submodule and/or the three-phase half-bridge inversion submodule.

5. The variable flow control device according to any one of claims 1 to 4, further comprising: a protection unit;

and the protection unit is used for filtering the zero-fire ground wire of the commercial power to form single-phase alternating current.

6. The variable flow control device according to any of claims 1 to 4, wherein the control unit comprises: a phase shift modulation module;

and the phase shift modulation module is used for outputting pulse signals to the rectification processing side and the inversion processing side in the current conversion unit respectively by utilizing two independent sawtooth waves and adopting a phase shift modulation technology and a circulation layered control mode so as to drive the rectification processing side and the inversion processing side in the current conversion unit through the pulse signals.

7. The variable flow control device according to claim 6, wherein the control unit further comprises: a rectification side sampling module;

the rectifying side sampling module is used for collecting a direct-current bus signal at a rectifying processing side in the converter unit, the bridge arm voltage of each bridge arm and/or the capacitor voltage of each single-phase rectifier submodule;

and the phase-shift modulation module is further used for adjusting the pulse signal at the rectification processing side in the current transformation unit based on a sawtooth carrier phase-shift modulation technology according to the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule, so as to realize the balance control of the direct-current bus signal at the rectification processing side, the bridge arm voltage of each bridge arm and/or the capacitance voltage of each single-phase rectification submodule.

8. The variable flow control device according to claim 6, wherein the control unit further comprises: an inversion side sampling module;

the inversion side sampling module is used for collecting three-phase electric signals at an inversion processing side in the current transformation unit, bridge arm inner ring currents of each bridge arm and/or capacitance voltages of each three-phase inversion submodule;

and the phase-shifting modulation module is also used for adjusting the pulse signal at the inversion processing side in the current transformation unit according to the three-phase electric signal at the inversion processing side, the bridge arm inner ring current of each bridge arm and/or the capacitance voltage of each three-phase inversion submodule, so as to realize the outer ring control and the interphase balance of the three-phase electric signal at the inversion processing side, the bridge arm inner ring current suppression of each bridge arm and/or the layered control of the capacitance voltage balance of each three-phase inversion submodule.

9. The variable flow control device according to claim 6, wherein the control unit further comprises: a load side sampling module;

the load side sampling module is used for collecting the three-phase current, the rotor position and/or the rotor speed of the motor at the output side of the converter unit;

and the phase shift modulation module is also used for adjusting pulse signals at a rectification processing side and/or an inversion processing side in the current conversion unit according to the three-phase current, the rotor position and/or the rotor speed of the motor so as to realize closed-loop frequency conversion control of the motor at the output side of the current conversion unit.

10. An electric machine, comprising: a variable flow control device as claimed in any one of claims 1 to 9.

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