CN108183621B - Power density improving method of single-phase quasi-Z source inverter based on SiC - Google Patents
Power density improving method of single-phase quasi-Z source inverter based on SiC Download PDFInfo
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from dc input or output
- H02M1/15—Arrangements for reducing ripples from dc input or output using active elements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a power density improving method of a single-phase quasi-Z source inverter based on SiC, which comprises the following steps: the system comprises a direct current power supply, a quasi-Z source network, a full SiC power module, a load branch and an active filtering branch. The invention effectively controls the switching tube of the active filtering branch circuit to transfer the pulsating power of the double frequency component in the alternating current output power to the energy storage capacitor of the active filtering branch circuit. Therefore, the direct current side quasi-Z source network capacitor and the inductor only need to process the pulsating voltage and current generated by the high-frequency switching frequency, and the capacitor of the active filtering branch operates in alternating current, so that larger pulsation is allowed, the value of the capacitor is greatly reduced compared with that of the direct current side electrolytic capacitor, and the film capacitor can be used for prolonging the service life.
Description
Technical Field
The invention relates to the technical field of power electronic current transformation, in particular to a power density improving method of a single-phase quasi-Z source inverter based on SiC.
Background
The single-phase quasi-Z source inverter attracts more and more researches applied in a photovoltaic power generation system in recent years, because the single-phase quasi-Z source inverter overcomes the limitation of the boosting ratio of the traditional inverter by single-stage conversion, has wider photovoltaic voltage processing capacity, and does not need dead zone control in a straight-through state, thereby greatly simplifying debugging, reducing the interference of an output side and improving the stability of the inverter system. In addition to being used as an independent photovoltaic inverter, the single-phase quasi-Z-source inverter can also be used as a basic module to form a quasi-Z-source cascade multi-level photovoltaic inverter.
The scholars at home and abroad sequentially research the working principle, the control strategy, the photovoltaic grid-connected application and the like of the single-phase, three-phase and cascade quasi-Z source inverter. The single-phase quasi-Z source inverter outputs single-phase alternating voltage and current, so that alternating output power contains double-frequency component pulsating power, the double-frequency component pulsating power is transmitted to a direct current side, and quasi-Z source network capacitors and inductors are needed to limit the pulsating power to be transmitted to a direct current power supply, so that the influence on the performance of the direct current power supply is reduced.
In order to reduce the influence of the ac side double frequency component pulsating power on the dc power supply as much as possible, it is necessary to limit the double frequency component pulsating of the dc side voltage and current to be within an allowable range. For example, it is necessary to limit the ripple of the double frequency component on the inductor current to 20% of the average value of the dc component of the current, and to limit the ripple of the double frequency component on the dc bus voltage to 5% of the peak value of the dc bus current. As a result, a large quasi-Z source network capacitance and inductance are required, and there is a study to attenuate the pulsating power of the double frequency component on the quasi-Z source inductance current by the control strategy, but a large quasi-Z source network capacitance is still required to limit the pulsating power of the double frequency component on the direct current side to the engineering allowable range.
Under the condition that the technology of the existing 1200V wide bandgap silicon carbide (SiC) device is mature, the use of the SiC device for improving the switching frequency of a power switch tube, reducing loss and improving temperature stability is a trend in the power electronic current transformation field. Three-phase quasi-Z source inverters based on SiC have been studied by students, including parameter design, power loss analysis, and the like. However, if the SiC device is directly applied to a single-phase quasi-Z source inverter, the passive device size, system volume and quasi-Z source network weight of the single-phase quasi-Z source inverter will not be significantly improved even if the switching frequency is increased due to the double frequency component ripple problem on the dc side described above. If SiC devices are used without significantly increasing the system power density, the advantages of SiC devices are lost.
Disclosure of Invention
The invention aims to provide a power density improving method of a single-phase quasi-Z source inverter based on SiC, which is used for solving the problems that the power density of the inverter is not high because passive device parameters, volume, weight and the like are too large in order to reduce the influence of double-frequency component pulsating power on a direct current power supply of the conventional single-phase quasi-Z source inverter.
In order to achieve the above object, the technical scheme of the present invention provides a single-phase quasi-Z source inverter based on SiC, the single-phase quasi-Z source inverter comprising: direct current power supply, quasi-Z source network, full SiC power module, load branch and active filtering branch, the quasi-Z source network is composed of two inductors L 1 And L 2 Two capacitors C 1 And C 2 One of the twoDiode D 1 The full SiC power module is formed by connecting and embedding a direct current power supply and an inverter direct current bus, and the full SiC power module is formed by four inverter load power switching tubes S 1 ～S 4 Two active filter branch switching tubes S 5 And S is 6 Connection formation, inverter load power switching tube S 1 And S is 2 Inverter load power switching tube S 3 And S is 4 Active filtering branch switching tube S 5 And S is 6 The parallel branches of the first inverter load power switch tube group and the second inverter load power switch tube group and the parallel branches of the active filter tube group are connected in parallel to a direct current bus, and the load branches are connected in series with a load inductance L through the parallel branches of the first inverter load power switch tube group f And a load resistor R L And then is connected to a parallel branch of a second inverter load power switch tube group, and the active filtering branch is connected with a filtering inductor L in series through the parallel branch of the active filtering branch switch tube group 3 And compensation capacitor C 3 And then connected to the dc bus.
Further, the positive electrode of the direct current power supply is sequentially connected with an inductor L in series 1 Diode D 1 And inductance L 2 And then is connected to a DC bus connected with the positive electrode of a DC power supply, and a capacitor C 1 Is connected to diode D 1 And inductance L 2 On the connecting line between the capacitors C 1 The other end of the capacitor C is connected to a direct current bus connected with the negative electrode of the direct current power supply 2 And diode D 1 And inductance L 2 And the DC buses are connected in parallel to the positive electrode of the DC power supply.
Further, one end of the load branch is connected to the inverter load power switch tube S 1 And S is 2 The other end of the load branch is connected to the inverter load power switch tube S 3 And S is 4 And the second inverter load power switch tube group is connected to the parallel branch connection line.
Further, the methodThe active filtering branch is connected with a filtering inductance L in series 3 And compensation capacitor C 3 Previously connected to an active filtering branch switching tube S 5 And S is 6 The active filtering branch switch tube group is connected to the parallel branch connecting line.
Further, the inverter load power switching tube S 1 ～S 4 The device has two working states of direct connection and non-direct connection: in the through state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 At the same time, the quasi-Z source network diode D outputs power to the load when conducting 1 Disconnecting, DC power supply and quasi-Z source network capacitor C 1 And C 2 Give accurate Z source network inductance L 1 And L 2 Charging; in a non-pass state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 Complementary conduction pair load output power, quasi-Z source network diode D 1 Conduction, direct current power supply and quasi-Z source network inductance L 1 And L 2 Give accurate Z source network electric capacity C 1 And C 2 Charging while simultaneously powering the load.
Further, the active filtering branch switching tube S 5 And S is 6 Full complementary conduction to transfer the pulsating power of the double frequency component of the load power to the compensation capacitor C of the active filtering branch 3 In the active filter branch, the filter inductance L of the active filter branch 3 The method is mainly used for inhibiting high-frequency ripple waves of the active filtering branch current.
The invention also discloses a power density improving method of the single-phase quasi-Z source inverter based on SiC, which comprises the following steps: selecting a corresponding SiC power switching device according to the power and voltage grade of the single-phase quasi-Z source inverter and connecting the corresponding SiC power switching device to form a full SiC power module; the total on-power loss and the total on-off power loss of the power devices of the all-SiC power module of the single-phase quasi-Z-source inverter are obtained by analyzing the on-power loss and the on-off power loss of the power devices of the all-SiC power module; analyzing the values of the total on-power loss and the total on-off power loss of the power switching devices of the all-SiC power modules under the switching frequencies of the power switching devices of the different all-SiC power modules; when the active filtering branch is provided, the direct-current side inductance and the capacitor only need to limit the pulsation caused by the switching frequency of a power switching device of the full SiC power module, and when the power and the voltage of the inverter are fixed, the direct-current side passive device parameter is completely inversely proportional to the switching frequency, and the higher the switching frequency is, the smaller the inductance and the capacitance parameter is; under the condition of meeting the total efficiency requirement, the switching frequency of a power switching device of the all-SiC power module is improved, the parameters of a passive device are reduced, and the power density of the single-phase quasi-Z source inverter is improved; selecting the switching frequency of a power switching device of the full SiC power module according to the total efficiency requirement; designing passive element parameters meeting the requirements of direct-current side quasi-Z source network inductance current and direct-current bus voltage ripple according to the switching frequency of the selected full-SiC power module power switching device and the passive element parameter calculation group of the single-phase quasi-Z source inverter; the passive element parameter calculation formula of the single-phase quasi-Z source inverter is as follows:
Wherein V is DC Is the direct-current power supply voltage, D is the inverter load power switch tube S 1 ～S 4 Duty cycle of pass-through state, r i Is the inductance current ripple coefficient, I L For the quasi-Z source network inductance current average value, f s ' is the switching frequency of the load power switching tube of the inverter, r v Ripple coefficient of voltage peak of DC bus, V PN Is the DC bus voltage.
Further, the analysis method of the on-power loss and the on-off power loss of the power switch device of the all-SiC power module comprises the following steps: active filtering branch circuit-based SiC power switch device electrical parameter and active filtering branch circuit power switch loss analysis type group calculate active filtering branch circuit switch tube S 5 And S is 6 Total conduction power loss of MOSFET and anti-parallel diode and active filtering branch switching tube S 5 And S is 6 MOSFETs and (2) ofTotal on-off power loss of the anti-parallel diode; the active filtering branch power switching loss analysis formula is as follows:
wherein d act (t) and d zero (t) duty cycles, v, of the active filter leg active state and zero state, respectively m3 (t)＝2u C (t)/V PN -1，u C (t) compensating capacitor C for active filter branch 3 V of (2) PN Is the voltage of a direct current bus;
P CON_MOS switching tube S for active filtering branch 5 And S is equal to 6 The total on-power loss, P, of the MOSFET ON_Diode Is S 5 And S is equal to 6 Total on-power loss of anti-parallel diode of R DS The conduction internal resistance of MOSFET of the active filtering branch switching tube is V F Forward voltage drop of antiparallel diode of active filtering branch switching tube, R F Is the conduction internal resistance of the anti-parallel diode of the active filtering branch switching tube,filtering inductance L for active filtering branch 3 Average current of (2); dωt is the integral of the product of fundamental angular frequency ω and time t;
P SW_MOS switching tube S for active filtering branch 5 And S is equal to 6 The total on-off power loss, P, of the MOSFET REC_Diode Is S 5 And S is equal to 6 Total on-off power loss, f of anti-parallel diodes of (2) s Switching frequency of switching tube for active filtering branch circuit, E ON And E is OFF Respectively the active filtering branch switching tubes are at the reference voltage V r And reference current I r The energy is turned on and off every pulse;
load branch-based SiC power switching device electrical parameter and load branch power switching loss analysis type group calculation inverter load power switching tube S 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode of (C) and inverter load power switching tube S 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode; the inverter load power switching loss analysis type is as follows:
Wherein P is CON_S14 Power switch tube S for inverter load 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode, P SW_S14 Power switch tube S for inverter load 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode of the (B), M is the quasi-Z source inverter load power switching tube S 1 ～S 4 Modulation index, R' DS Conduction internal resistance of MOSFET of load power switch tube of inverter, i o The method is characterized in that the method comprises the steps of outputting voltage and current to a load for a single-phase quasi-Z source inverter, wherein omega is fundamental wave angular frequency, and D is an inverter load power switch tube S 1 ～S 4 The duty cycle of the pass-through state, dωt, is the integral of the product of the fundamental angular frequency ω and the time t, V' F Forward voltage drop for anti-parallel diode of inverter load power switching tube, R' F Is inversion ofConduction internal resistance of anti-parallel diode of load power switching tube, I L For the quasi-Z source network inductance current average value, I o For the amplitude of the fundamental current, f s ' switching frequency of inverter load power switching tube, V PN For DC bus voltage, E' ON And E' OFF The reference voltage V 'is respectively used for the inverter load power switching tube' r And a reference current I' r The energy is turned on and off per pulse.
Further, the active filtering branch switching tube S 5 And S is 6 Completely independent of inverter load power switching tube S 1 ～S 4 Compensating capacitor C 3 The voltage is expressed as:
due to u C 2 (t) is not less than 0, let A=P m /ωC 3 ≥V o I o /2ωC 3 The active filtering branch circuit compensates the capacitor C 3 Voltage and filter inductance L of (2) 3 The average currents of (a) are expressed as:
the active filtering branch compensation capacitor C 3 Maximum value of voltage of (2) and DC bus voltage V PN The peak value is consistent, then P needs to be compensated r Active filter branch compensation capacitor C of (a) 3 At least is:
the active filtering branch circuit filtering inductance L 3 And compensating capacitor C 3 In series to suppress the active filtering branch current i C The high-frequency ripple wave generated by the medium switching frequency is not more than 20%;
wherein A is the pulsating work of the double frequency componentRate P r And compensation capacitor C 3 Constant of value dependence, V o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time, P m Rated power, P o Output power to the load for the single-phase quasi-Z source inverter.
Further, the voltage u output to the load at the single-phase quasi-Z source inverter o ＝V o sin (ωt) and currentIn the case of (a), the output power of the single-phase quasi-Z source inverter to the load is:
the output power of the single-phase quasi-Z source inverter output to the load contains the pulse power P with double frequency component r The double frequency component pulse power P r The method comprises the following steps:
wherein V is o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time.
The invention has the following advantages:
the invention discloses a single-phase quasi-Z source inverter with an active filtering branch, which is used for transmitting pulsating power of double frequency components in alternating current output power to an energy storage capacitor of the active filtering branch through effectively controlling a switching tube of the active filtering branch. Therefore, the direct current side quasi-Z source network capacitor and the inductor only need to process the pulsating voltage and current generated by the high-frequency switching frequency, and the capacitor of the active filtering branch operates in alternating current, so that larger pulsation is allowed, the value of the capacitor is greatly reduced compared with that of the direct current side electrolytic capacitor, and the film capacitor can be used for prolonging the service life. The on-power loss and the on-off power loss of the power switching devices of the full SiC power module are calculated, so that the loss of all the power switching devices of the full SiC power module is analyzed, and the switching frequency is selected; based on a wide forbidden band SiC device, the switching frequency is improved, the active filtering branch compensates the pulsating power of the double frequency component, and the parameters of a direct current side reference Z source network element are greatly reduced; compared with the traditional single-phase quasi-Z source inverter, the passive element parameters of the whole inverter system are reduced, the volume, the weight and the like are greatly reduced, and the power density is improved.
Drawings
Fig. 1 is a schematic diagram of a connection structure of a conventional single-phase quasi-Z source inverter.
Fig. 2 is a schematic diagram of a connection structure of a single-phase quasi-Z source inverter based on SiC according to the present disclosure.
Fig. 3 is a schematic diagram illustrating on-power loss and on-off-power loss analysis of a power switching device of an all-SiC power module of an active filtering branch of a single-phase quasi-Z-source inverter based on SiC according to the present invention, (a) an active filtering branch switching tube S 5 And S is 6 An on-off control strategy diagram of (2); (b) Active filtering branch switching tube S 5 Voltage and current waveforms of (a) are shown.
Fig. 4 is a schematic diagram of the relationship between the total on-power loss and the total on-off power loss of the all-SiC power module power switching device of the single-phase quasi-Z source inverter disclosed by the invention and the switching frequency of the all-SiC power module power switching device.
FIG. 5 is a simulation result of a single-phase quasi-Z source inverter based on SiC disclosed in the present invention; the method sequentially comprises the following steps from top to bottom: (a) DC input voltage simulation result schematic diagram, (b) quasi-Z source network capacitor C 1 A voltage simulation result schematic diagram, and (c) a direct current bus voltage simulation result schematic diagram.
Fig. 6 is a schematic diagram of simulation results of input current and dc bus voltage of a single-phase quasi-Z source inverter based on SiC in 7 control cycles.
FIG. 7 is a simulation result of a single-phase quasi-Z source inverter based on SiC disclosed in the present invention; the method sequentially comprises the following steps from top to bottom: (a) an active filter branch compensation capacitance current simulation result schematic, (b) an active filter branch compensation capacitance voltage simulation result schematic, and (c) an alternating current output current simulation result schematic.
Detailed Description
The following examples are illustrative of the invention and are not intended to limit the scope of the invention.
Example 1
Fig. 1 is a schematic diagram of a connection structure of a conventional single-phase quasi-Z source inverter, and fig. 2 is a schematic diagram of a connection structure of a SiC-based single-phase quasi-Z source inverter according to the present disclosure. As shown in fig. 2, the single-phase quasi-Z source inverter disclosed in the present embodiment includes: direct current power supply, quasi-Z source network, full SiC power module, load branch and active filtering branch, the quasi-Z source network is composed of two inductors L 1 And L 2 Two capacitors C 1 And C 2 One diode D 1 The full SiC power module is formed by connecting and embedding a direct current power supply and an inverter direct current bus, and the full SiC power module is formed by four inverter load power switching tubes S 1 ～S 4 Two active filter branch switching tubes S 5 And S is 6 Connection formation, inverter load power switching tube S 1 And S is 2 Inverter load power switching tube S 3 And S is 4 Active filtering branch switching tube S 5 And S is 6 The parallel branches of the first inverter load power switch tube group and the second inverter load power switch tube group and the parallel branches of the active filter tube group are connected in parallel to a direct current bus, and the load branches are connected in series with a load inductance L through the parallel branches of the first inverter load power switch tube group f And a load resistor R L A parallel branch connected to the second inverter load power switch tube group, the active power switch tube groupThe filtering branch is connected with the filtering inductance L in series through the parallel branch of the active filtering branch switch tube group 3 And compensation capacitor C 3 And then connected to the dc bus. In fig. 1 and 2, V DC Is the direct current power supply voltage, i L1 And i L2 Respectively the inductance L 1 And L 2 Current, v C1 And v C2 Respectively the capacitance C 1 And C 2 V of (2) PN For DC bus voltage, u o And i o Voltage and current output to load by single-phase quasi-Z source inverter respectively, u C And i C Compensating capacitor voltage and current for the active filter branch.
Further, the positive electrode of the direct current power supply is sequentially connected with the inductor L in series 1 Diode D 1 And inductance L 2 And then is connected to a DC bus connected with the positive electrode of a DC power supply, and a capacitor C 1 Is connected to diode D 1 And inductance L 2 On the connecting line between the capacitors C 1 The other end of the capacitor C is connected to a direct current bus connected with the negative electrode of the direct current power supply 2 And diode D 1 And inductance L 2 And the DC buses are connected in parallel to the positive electrode of the DC power supply. One end of the load branch is connected to the inverter load power switch tube S 1 And S is 2 The other end of the load branch is connected to the inverter load power switch tube S 3 And S is 4 And the second inverter load power switch tube group is connected to the parallel branch connection line. The active filtering branch is connected with a filtering inductance L in series 3 And compensation capacitor C 3 Previously connected to an active filtering branch switching tube S 5 And S is 6 The active filtering branch switch tube group is connected to the parallel branch connecting line.
In this embodiment, the inverter load power switching tube S 1 ～S 4 The device has two working states of direct connection and non-direct connection: in the through state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 At the same time, the quasi-Z source network diode D outputs power to the load when conducting 1 DisconnectingDC power supply and quasi-Z source network capacitor C 1 And C 2 Give accurate Z source network inductance L 1 And L 2 Charging; in a non-pass state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 Complementary conduction pair load output power, quasi-Z source network diode D 1 Conduction, direct current power supply and quasi-Z source network inductance L 1 And L 2 Give accurate Z source network electric capacity C 1 And C 2 Charging while simultaneously powering the load. Active filtering branch switching tube S 5 And S is 6 Full complementary conduction to transfer the pulsating power of the double frequency component of the load power to the compensation capacitor C of the active filtering branch 3 In the active filter branch, the filter inductance L of the active filter branch 3 The method is mainly used for inhibiting high-frequency ripple waves of the active filtering branch current.
Description of active and passive devices: simply speaking, devices requiring an energy (electrical) source are called active devices, and devices requiring no energy (electrical) source are called passive devices. Active devices are commonly used for signal amplification, conversion, etc.; passive devices are used for signal transmission or "signal amplification" by directivity. The capacitance, resistance, inductance are all passive devices, and the IC, module, etc. are all active devices. It is colloquially known that a power source is required to display its characteristics, namely active components such as transistors. And the passive element can display the characteristic without power supply.
The power density improving method of the single-phase quasi-Z source inverter based on SiC disclosed in the embodiment comprises the following steps: selecting a corresponding SiC power switching device according to the power and voltage grade of the single-phase quasi-Z source inverter and connecting the corresponding SiC power switching device to form a full SiC power module; the total on-power loss and the total on-off power loss of the power devices of the all-SiC power module of the single-phase quasi-Z-source inverter are obtained by analyzing the on-power loss and the on-off power loss of the power devices of the all-SiC power module; analyzing the values of the total on-power loss and the total on-off power loss of the power switching devices of the all-SiC power modules under the switching frequencies of the power switching devices of the different all-SiC power modules; when the active filtering branch is provided, the direct-current side inductance and the capacitor only need to limit the pulsation caused by the switching frequency of a power switching device of the full SiC power module, and when the power and the voltage of the inverter are fixed, the direct-current side passive device parameter is completely inversely proportional to the switching frequency, and the higher the switching frequency is, the smaller the inductance and the capacitance parameter is; under the condition of meeting the total efficiency requirement, the switching frequency of a power switching device of the all-SiC power module is improved, the parameters of a passive device are reduced, and the power density of the single-phase quasi-Z source inverter is improved; selecting the switching frequency of a power switching device of the full SiC power module according to the total efficiency requirement; and designing passive element parameters meeting the requirements of direct-current side quasi-Z source network inductance current and direct-current bus voltage ripple according to the switching frequency of the selected full-SiC power module power switching device and the passive element parameter calculation group of the single-phase quasi-Z source inverter.
In the embodiment, the working principle and parameter selection of the single-phase quasi-Z source inverter with the active filtering branch are analyzed, the on-power loss and the on-off power loss of the power switching device of the full SiC power module are analyzed when the SiC device is used based on the analysis, and then the switching frequency and the passive element parameters of the optimal power switching device are designed under the condition that the system efficiency requirement is met.
As shown in fig. 2, the working principle of the single-phase quasi-Z source inverter based on SiC disclosed in this embodiment is as follows: the work of the load power phase is consistent with that of the traditional single-phase quasi-Z source inverter, and the voltage u output to the load by the single-phase quasi-Z source inverter o ＝V o sin (ωt) and currentIn the case of (a), the output power of the single-phase quasi-Z source inverter to the load is:
the output power of the single-phase quasi-Z source inverter output to the load contains the pulse power P with double frequency component r Two-frequency component pulsating power P r The method comprises the following steps:
wherein V is o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time.
Active filtering branch switching tube S 5 And S is 6 Completely independent of inverter load power switching tube S 1 ～S 4 Compensating capacitor C 3 The voltage is expressed as:
Due to u C 2 (t) is not less than 0, let A=P m /ωC 3 ≥V o I o /2ωC 3 Active filter branch compensation capacitor C 3 Voltage and filter inductance L of (2) 3 The average currents of (a) are expressed as:
parameters of the single-phase quasi-Z source inverter with the active filtering branch in this embodiment are selected as follows:
active filter branch compensation capacitor C 3 Maximum value of voltage of (2) and DC bus voltage V PN Peak value is consistent, and the capacitor C is compensated by the active filtering branch 3 Voltage and filter inductance L of (2) 3 To compensate P r Active filter branch compensation capacitor C of (a) 3 At least is:
wherein A is the sum of two times the frequency componentPulsating power P r And compensation capacitor C 3 Constant of value dependence, V o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time, P m Rated power, P o Output power to the load for the single-phase quasi-Z source inverter.
Active filtering branch filter inductance L 3 And compensating capacitor C 3 In series to suppress the active filtering branch current i C The high frequency ripple generated by the medium switching frequency is not more than 20%.
Compensation capacitance C due to active filter branch 3 The pulse power of the double frequency component is compensated, the direct current side quasi-Z source network inductance and capacitance only restrain the high frequency switch pulse, and the switch ripple on the inductance current is limited to r i Limiting the switching ripple on the dc bus voltage to r v The passive element parameter calculation formula of the single-phase quasi-Z source inverter is as follows:
wherein V is DC Is the direct-current power supply voltage, D is the inverter load power switch tube S 1 ～S 4 Duty cycle of pass-through state, r i Is the inductance current ripple coefficient, I L For the quasi-Z source network inductance current average value, f s ' is the switching frequency of the load power switching tube of the inverter, r v Ripple coefficient of voltage peak of DC bus, V PN Is the DC bus voltage.
The on-power loss and the on-off power loss of the power switching device of the full SiC power module are analyzed as follows:
firstly, an active filtering branch switching tube S is calculated based on the electrical parameters of an SiC power switching device of an active filtering branch and an active filtering branch power switching loss analysis type group 5 And S is 6 MO of (2)Total conduction power loss of SFET and antiparallel diode and active filtering branch switching tube S 5 And S is 6 The total on-off power loss of the MOSFET and the anti-parallel diode.
Fig. 3 (a) shows an active filter branch switching tube S disclosed in the present embodiment 5 And S is 6 Is a schematic diagram of the on and off control strategy of (a). Compensating the capacitance C by the active filter branch 3 The compensation capacitor voltage in the voltage calculation formula of (2) can obtain the compensation capacitor voltage reference value u * C Which is in accordance with the actual capacitance voltage u C Comparing the two values, and passing through a proportional-integral-resonance (PIR) regulator and feedforward control u * C /0.5V PN -1, jointly obtaining the modulated signal v m3 Will v m3 V compared with triangular carrier m3 S greater than triangular carrier 5 Opening and S 6 Turn off, otherwise S 5 Turn off and S 6 Opening.
Based on the active filtering branch switching tube S shown in FIG. 3 (a) 5 And S is 6 On and off control strategy of (a), FIG. 3 (b) shows an active filter branch switching tube S 5 Voltage and current waveforms of (a) and (b) switch S 6 Similar to this. It can be seen that the active filtering branch switching tube S 5 And S is 6 There is an active state and a zero state. In the active state, the current i is in the branch C During positive period, active filtering branch switch tube S 5 The MOSFET in (a) flows a current; in the active filtering branch current i C During the negative period, the active filtering branch switch tube S 5 Is freewheeling. In the zero state, the active filtering branch switching tube S 5 No current flows, the voltage of which is clamped at the voltage peak value V of the DC bus PN When the quasi-Z source load power branch has a through state, the active filter branch switch tube S 5 Will drop to zero as will the inverter load power switching tube S in fig. 3 (b) 1 Active filtering branch switching tube S in switching signal straight-through period 5 The voltages are shown in fig. 3 (b).
As can be taken from fig. 3, the duty cycles of the active filter leg active state and the zero state are respectively:
wherein d act (t) and d zero (t) duty cycles, v, of the active filter leg active state and zero state, respectively m3 (t)＝2u C (t)/V PN -1，u C (t) compensating capacitor C for active filter branch 3 V of (2) PN Is the DC bus voltage.
The conduction power loss of the active filtering branch switching tube is obtained as follows:
wherein P is CON_MOS Switching tube S for active filtering branch 5 And S is equal to 6 The total on-power loss, P, of the MOSFET ON_Diode Is S 5 And S is equal to 6 Total on-power loss of anti-parallel diode of R DS The conduction internal resistance of MOSFET of the active filtering branch switching tube is V F Forward voltage drop of antiparallel diode of active filtering branch switching tube, R F Is the conduction internal resistance of the anti-parallel diode of the active filtering branch switching tube,filtering inductance L for active filtering branch 3 Average current of (2); dωt is the integral of the product of the fundamental angular frequency ω and time t.
From fig. 3, active filter branch switching tube S 5 The voltage across it is seen that there are two voltage switches in each switching cycle, however, as previously described, the voltage drop during the pass-through state will not have power loss due to zero current switching, then S can be obtained 5 And S is 6 MOSFET and anti-parallel diode of (E)The total on-off power loss of the tube is as follows:
wherein P is SW_MOS Switching tube S for active filtering branch 5 And S is equal to 6 The total on-off power loss, P, of the MOSFET REC_Diode Is S 5 And S is equal to 6 Total on-off power loss, f of anti-parallel diodes of (2) s Switching frequency of switching tube for active filtering branch circuit, E ON And E is OFF Respectively the active filtering branch switching tubes are at the reference voltage V r And reference current I r The energy is turned on and off per pulse.
Next, an inverter load power switching tube S is calculated based on the SiC power switching device electrical parameters of the load branch and the load branch power switching loss analysis group 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode of (C) and inverter load power switching tube S 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode; the inverter load power switching loss analysis type is as follows:
wherein P is CON_S14 Power switch tube S for inverter load 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode, P SW_S14 Power switch tube S for inverter load 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode of the (B), M is the quasi-Z source inverter load power switching tube S 1 ～S 4 Modulation index, R' DS Conduction internal resistance of MOSFET for inverter load power switch tube，i o The method is characterized in that the method comprises the steps of outputting voltage and current to a load for a single-phase quasi-Z source inverter, wherein omega is fundamental wave angular frequency, and D is an inverter load power switch tube S 1 ～S 4 The duty cycle of the pass-through state, dωt, is the integral of the product of the fundamental angular frequency ω and the time t, V' F Forward voltage drop for anti-parallel diode of inverter load power switching tube, R' F Conduction internal resistance of anti-parallel diode of load power switch tube of inverter, I L For the quasi-Z source network inductance current average value, I o For the amplitude of the fundamental current, f s ' switching frequency of inverter load power switching tube, V PN For DC bus voltage, E' ON And E' OFF The reference voltage V 'is respectively used for the inverter load power switching tube' r And a reference current I' r The energy is turned on and off per pulse.
In addition, when analyzing and calculating the total on-power loss and the total on-off power loss of the power device of the all-SiC power module of the single-phase quasi-Z source inverter, the calculated active filtering branch switching tube S is used for controlling the power device to switch on and off 5 And S is 6 Total conduction power loss of MOSFET and anti-parallel diode and active filtering branch switching tube S 5 And S is 6 Total on-off power loss of MOSFET and anti-parallel diode and inverter load power switching tube S 1 ～S 4 On-power loss of MOSFET and anti-parallel diode of (c) and inverter load power switching tube S 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode is respectively added to obtain the high-voltage power supply.
According to the method, the system parameters are selected and designed by taking a single-phase quasi-Z source inverter with 21kW, 300-600V of direct current input voltage and 450V of alternating current voltage basic amplitude as an example. The design requirements are as follows: target efficiency 97%, total Harmonic Distortion (THD) of alternating output current not more than 2%, quasi-Z source network inductance current ripple coefficient r i Ripple coefficient r of DC bus voltage peak value less than 20% v Less than 1%, and the inductance and capacitance parameters of the quasi-Z source network are as small as possible on the basis of meeting the requirements of the points.
Single-phase standard based on 21kWZ-source inverter System parameters, in this embodiment, a module CAS120M12BM2 with 1200V/193A full SiC MOSFET and anti-parallel diode is selected, and an active filter branch switching tube S is calculated from an active filter branch power switching loss analysis group 5 And S is 6 Total conduction power loss of MOSFET and anti-parallel diode and active filtering branch switching tube S 5 And S is 6 The total on-off power loss of the MOSFETs and anti-parallel diodes of (c) and the required SiC power switching device electrical parameters of the main active filter leg can be obtained from the data table of the CAS120M12BM2 module.
SiC power switching device electrical parameter based on load branch and load branch power switching loss analysis type inverter load power switching tube S 1 ～S 4 On-power loss of MOSFET and anti-parallel diode of (c) and inverter load power switching tube S 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode.
And analyzing and calculating total on-power loss and total on-off power loss of the full SiC power module power device of the single-phase quasi-Z source inverter according to the result, and analyzing values of the total on-power loss and the total on-off power loss of the full SiC power module power switch device under the switching frequencies of different full SiC power module power switch devices, wherein the total on-power loss of the full SiC power module power switch device is equal to the total on-off power loss of the full SiC power module power device at the switching frequency of 40kHz, and the total on-off power loss of the full SiC power module power device is about twice of the total on-power loss of the full SiC power module power switch device at the frequency of 80kHz as shown in fig. 4. Therefore, the embodiment selects 70kHz as the switching tube frequency, and the total loss on the power switching device of the all-SiC power module is about 2.5%, and the total efficiency can be less than 97% by adding the stray loss in the inductance and capacitance in the circuit.
Table I is a comparison table of passive element parameters of a single-phase quasi-Z source inverter based on SiC and a conventional single-phase quasi-Z source inverter designed in this embodiment. It can be seen that the single-phase quasi-Z source inverter based on SiC according to this embodiment greatly reduces parameters of quasi-Z source network elements compared with the conventional single-phase quasi-Z source inverter. For a 21kW single-phase quasi-Z source inverter based on SiC, the overall system volume and weight will be greatly reduced. Although the active filtering branch is added with a bridge arm, a filtering inductor and a compensation capacitor, the bridge arm and the load power bridge arm of the active filtering branch can be realized by a 3-bridge arm integrated module based on the current mature SiC device, such as a CAS120M12BM2 module selected in the design of the embodiment, and compared with the capacitors of 1500 mu F on two direct current sides in the traditional single-phase quasi-Z source inverter system, the volume and the cost are greatly reduced, and the service life of the capacitor is prolonged. The power density of a single-phase quasi-Z source inverter system will be greatly improved without affecting efficiency.
Table I: siC-based single-phase quasi-Z-source inverter and passive element parameter comparison table of traditional single-phase quasi-Z-source inverter
The invention provides a single-phase quasi-Z source inverter based on SiC at 70kHz, which is simulated in PLECS software. According to the design method, the quasi-Z source network inductance L in simulation 1 And L 2 And capacitor C 1 And C 2 60 mu H and 45 mu F respectively, and compensating capacitor C of active filter branch 3 450 mu F, filter inductance L 3 40. Mu.H. The simulation working condition is that the input voltage is 450V, and the voltage peak value 563V of the direct current bus is the same, so that the amplitude of the alternating current voltage is 450V. As can be seen from fig. 6, when the single-phase quasi-Z source inverter operates at a switching frequency of 70kHz and the ratio of ripple of the inductor current to average value is less than 20%, the ripple on the voltage peak of the dc bus is hardly visible, the selected quasi-Z source network parameters meet the design requirement, and the dc side has no double frequency component pulsating power, as shown in fig. 5. As can be seen from fig. 7, the active filtering branch compensation capacitor transfers the pulsating power of the double frequency component to the compensation capacitor in an alternating current manner, so that the sine degree of the alternating output current of the single-phase quasi-Z source inverter is improved, and the total harmonic distortion rate is 1.33%<2％。
While the invention has been described in detail in the foregoing general description and specific examples, it will be apparent to those skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (9)
1. A method for improving power density of a single-phase quasi-Z source inverter based on SiC, the single-phase quasi-Z source inverter comprising: direct current power supply, quasi-Z source network, full SiC power module, load branch and active filtering branch, the quasi-Z source network is composed of two inductors L 1 And L 2 Two capacitors C 1 And C 2 One diode D 1 The full SiC power module is formed by connecting and embedding a direct current power supply and an inverter direct current bus, and the full SiC power module is formed by four inverter load power switching tubes S 1 ～S 4 Two active filter branch switching tubes S 5 And S is 6 Connection formation, inverter load power switching tube S 1 And S is 2 Inverter load power switching tube S 3 And S is 4 Active filtering branch switching tube S 5 And S is 6 The parallel branches of the first inverter load power switch tube group and the second inverter load power switch tube group and the parallel branches of the active filter tube group are connected in parallel to a direct current bus, and the load branches are connected in series with a load inductance L through the parallel branches of the first inverter load power switch tube group f And a load resistor R L And then is connected to a parallel branch of a second inverter load power switch tube group, and the active filtering branch is connected with a filtering inductor L in series through the parallel branch of the active filtering branch switch tube group 3 And compensation capacitor C 3 The rear end is connected to a direct current bus; the method comprises the following steps:
selecting a corresponding SiC power switching device according to the power and voltage grade of the single-phase quasi-Z source inverter and connecting the corresponding SiC power switching device to form a full SiC power module;
the total on-power loss and the total on-off power loss of the power devices of the all-SiC power module of the single-phase quasi-Z-source inverter are obtained by analyzing the on-power loss and the on-off power loss of the power devices of the all-SiC power module;
analyzing the values of the total on-power loss and the total on-off power loss of the power switching devices of the all-SiC power modules under the switching frequencies of the power switching devices of the different all-SiC power modules;
when the active filtering branch is provided, the direct-current side inductance and the capacitor only need to limit the pulsation caused by the switching frequency of a power switching device of the full SiC power module, and when the power and the voltage of the inverter are fixed, the direct-current side passive device parameter is completely inversely proportional to the switching frequency, and the higher the switching frequency is, the smaller the inductance and the capacitance parameter is;
under the condition of meeting the total efficiency requirement, the switching frequency of a power switching device of the all-SiC power module is improved, the parameters of a passive device are reduced, and the power density of the single-phase quasi-Z source inverter is improved;
Selecting the switching frequency of a power switching device of the full SiC power module according to the total efficiency requirement; and
Designing passive element parameters meeting the requirements of direct-current side quasi-Z source network inductance current and direct-current bus voltage ripple according to the switching frequency of the selected full-SiC power module power switching device and the passive element parameter calculation group of the single-phase quasi-Z source inverter; the passive element parameter calculation formula of the single-phase quasi-Z source inverter is as follows:
wherein V is DC Is the direct-current power supply voltage, D is the inverter load power switch tube S 1 ～S 4 Duty cycle of pass-through state, r i Is the inductance current ripple coefficient, I L For the quasi-Z source network inductance current average value, f s ' is the switching frequency of the load power switching tube of the inverter, r v Ripple coefficient of voltage peak of DC bus, V PN Is a direct current busA voltage.
2. The power density increasing method of a single-phase quasi-Z source inverter based on SiC according to claim 1, wherein the positive electrode of the dc power supply is sequentially connected in series with an inductance L 1 Diode D 1 And inductance L 2 And then is connected to a DC bus connected with the positive electrode of a DC power supply, and a capacitor C 1 Is connected to diode D 1 And inductance L 2 On the connecting line between the capacitors C 1 The other end of the capacitor C is connected to a direct current bus connected with the negative electrode of the direct current power supply 2 And diode D 1 And inductance L 2 And the DC buses are connected in parallel to the positive electrode of the DC power supply.
3. The method for increasing the power density of a single-phase quasi-Z source inverter based on SiC according to claim 1, wherein one end of the load branch is connected to an inverter load power switching tube S 1 And S is 2 The other end of the load branch is connected to the inverter load power switch tube S 3 And S is 4 And the second inverter load power switch tube group is connected to the parallel branch connection line.
4. The method of increasing power density of a single-phase quasi-Z source inverter based on SiC according to claim 1, wherein the active filter leg is connected in series with a filter inductance L 3 And compensation capacitor C 3 Previously connected to an active filtering branch switching tube S 5 And S is 6 The active filtering branch switch tube group is connected to the parallel branch connecting line.
5. The power density improvement method of a single-phase quasi-Z source inverter based on SiC according to claim 1, wherein the inverter loads power switching tube S 1 ～S 4 The device has two working states of direct connection and non-direct connection: in the through state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 At the same time, the quasi-Z source network diode D outputs power to the load when conducting 1 Disconnecting, DC power supply and quasi-Z source network capacitor C 1 And C 2 Give accurate Z source network inductance L 1 And L 2 Charging; in a non-pass state, the inverter load power switch tube S 1 And S is 2 Or the inverter load power switching tube S 3 And S is 4 Complementary conduction pair load output power, quasi-Z source network diode D 1 Conduction, direct current power supply and quasi-Z source network inductance L 1 And L 2 Give accurate Z source network electric capacity C 1 And C 2 Charging while simultaneously powering the load.
6. The method for increasing power density of a single-phase quasi-Z source inverter based on SiC of claim 4, wherein said active filtering bypass switching tube S 5 And S is 6 Full complementary conduction to transfer the pulsating power of the double frequency component of the load power to the compensation capacitor C of the active filtering branch 3 In the active filter branch, the filter inductance L of the active filter branch 3 The method is mainly used for inhibiting high-frequency ripple waves of the active filtering branch current.
7. The power density improvement method of a single-phase quasi-Z source inverter based on SiC according to any one of claims 1-6, wherein the analysis method of on-power loss and on-off-power loss of the power switching device of the all-SiC power module comprises:
Active filtering branch circuit-based SiC power switch device electrical parameter and active filtering branch circuit power switch loss analysis type group calculate active filtering branch circuit switch tube S 5 And S is 6 Total conduction power loss of MOSFET and anti-parallel diode and active filtering branch switching tube S 5 And S is 6 The total on-off power loss of the MOSFET and the anti-parallel diode; the active filtering branch power switching loss analysis formula is as follows:
P REC_Diode ＝0
wherein d act (t) and d zero (t) duty cycles, v, of the active filter leg active state and zero state, respectively m3 (t)＝2u C (t)/V PN -1，u C (t) compensating capacitor C for active filter branch 3 V of (2) PN Is the voltage of a direct current bus, i C An active filtering branch current;
P CON_MOS switching tube S for active filtering branch 5 And S is equal to 6 The total on-power loss, P, of the MOSFET ON_Diode Is S 5 And S is equal to 6 Total on-power loss of anti-parallel diode of R DS The conduction internal resistance of MOSFET of the active filtering branch switching tube is V F Forward voltage drop of antiparallel diode of active filtering branch switching tube, R F Is the conduction internal resistance of the anti-parallel diode of the active filtering branch switching tube,filtering inductance L for active filtering branch 3 Average current of (2); dωt is the integral of the product of fundamental angular frequency ω and time t;
P SW_MOS Switching tube S for active filtering branch 5 And S is equal to 6 The total on-off power loss, P, of the MOSFET REC_Diode Is S 5 And S is equal to 6 Total on-off power loss, f of anti-parallel diodes of (2) s Switching frequency of switching tube for active filtering branch circuit, E ON And E is OFF Respectively the active filtering branch switching tubes are at the reference voltage V r And reference current I r The energy is turned on and off every pulse;
load branch-based SiC power switching device electrical parameter and load branch power switching loss analysis type group calculation inverter load power switching tube S 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode of (C) and inverter load power switching tube S 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode; the inverter load power switching loss analysis type is as follows:
wherein P is CON_S14 Power switch tube S for inverter load 1 ～S 4 Total conduction power loss of MOSFET and anti-parallel diode, P SW_S14 Power switch tube S for inverter load 1 ～S 4 The total on-off power loss of the MOSFET and the anti-parallel diode of the (B), M is the quasi-Z source inverter load power switching tube S 1 ～S 4 Modulation index, R' DS Conduction internal resistance of MOSFET of load power switch tube of inverter, i o The method is characterized in that the method comprises the steps of outputting voltage and current to a load for a single-phase quasi-Z source inverter, wherein omega is fundamental wave angular frequency, and D is an inverter load power switch tube S 1 ～S 4 The duty cycle of the pass-through state, dωt, is the integral of the product of the fundamental angular frequency ω and the time t, V' F Forward voltage drop for anti-parallel diode of inverter load power switching tube, R' F Anti-parallel connection of load power switching tubes for inverterInternal resistance of diode conduction, I L For the quasi-Z source network inductance current average value, I o For the amplitude of the fundamental current, f s ' switching frequency of inverter load power switching tube, V PN For DC bus voltage, E' ON And E' OFF The reference voltage V 'is respectively used for the inverter load power switching tube' r And a reference current I' r The energy is turned on and off per pulse.
8. The method for increasing power density of a single-phase quasi-Z source inverter based on SiC of claim 7, wherein said active filtering branch switching tube S 5 And S is 6 Completely independent of inverter load power switching tube S 1 ～S 4 Compensating capacitor C 3 The voltage is expressed as:
due to u C 2 (t) is not less than 0, let A=P m /ωC 3 ≥V o I o /2ωC 3 The active filtering branch circuit compensates the capacitor C 3 Voltage and filter inductance L of (2) 3 The average currents of (a) are expressed as:
the active filtering branch compensation capacitor C 3 Maximum value of voltage of (2) and DC bus voltage V PN The peak value is consistent, then P needs to be compensated r Active filter branch compensation capacitor C of (a) 3 At least is:
the active filtering branch circuit filtering inductance L 3 And compensating capacitor C 3 In series to suppress havingSource filter branch current i C The high-frequency ripple wave generated by the medium switching frequency is not more than 20%;
wherein A is the pulse power P of the double frequency component r And compensation capacitor C 3 Constant of value dependence, V o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time, P m Rated power, P o Output power to the load for the single-phase quasi-Z source inverter.
9. The method of increasing power density of a single-phase SiC-based quasi-Z source inverter according to claim 8, wherein a voltage u output to a load at said single-phase quasi-Z source inverter o ＝V o sin (ωt) and currentIn the case of (a), the output power of the single-phase quasi-Z source inverter to the load is:
the output power of the single-phase quasi-Z source inverter output to the load contains the pulse power P with double frequency component r The double frequency component pulse power P r The method comprises the following steps:
wherein V is o And I o The amplitudes of the fundamental wave voltage and the current respectively, omega is the fundamental wave angular frequency,is the power factor angle, t is the time。
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| CN106655738A (en) * | 2015-11-02 | 2017-05-10 | 陈仲 | Electrolytic capacitor-free quasi single stage inverter and control method therefor |
| CN107546999A (en) * | 2017-08-22 | 2018-01-05 | 浙江大学 | A kind of band active power decouples single-phase ZVT inverter circuit and its modulator approach |
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