CN101237191A

CN101237191A - AC to AC converter

Info

Publication number: CN101237191A
Application number: CNA2007100631780A
Authority: CN
Inventors: 刘丛伟; 吴斌
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-01-30
Filing date: 2007-01-30
Publication date: 2008-08-06

Abstract

The invention relates to an AC to AC converter, belonging to the electric energy conversion technical field. The converter comprises a three-phase AC input connector which has three AC input terminals, a three-phase AC output connector which has three AC output terminals, a DC circuit which comprises two DC terminals and an energy storage component, a switch network which comprises three or two bridge arm circuit consisting of nine or six switch devices, with each bridge-arm circuit comprising three switch components and being connected to the corresponding AC input terminal and the corresponding output terminal, and a control system which is connected to the switch network for providing switching control signals for the switch devices to convert input AC electrical power from the input connector into output AC electrical power to the output connector, or to convert input AC electrical power from the output connector into output AC electrical power to the input connector. The invention utilizes a small quantity of asymmetric power switch components to convert input AC power into output AC power in a uniform or variable frequency operation mode.

Description

AC to AC converter

Technical field

The invention belongs to electric energy switch technology field, particularly the design of AC to AC converter.

Background technology

The electric energy conversion of input AC (AC) output AC (AC) exists in a large number in industrial quarters, particularly the two-way AC/DC/AC of three-phase (AC-to DC is to exchanging) current transformer has been applied in motor-driven, electricity generation system, series compensator and uninterruption power source (UPS) etc.This conversion provides sine-wave current and Adjustable Power Factor Current in input (electrical network) side and output (load) side.The two-way AC/DC/AC current transformer of traditional three-phase has comprised two three-phase PWM inverters that connected by the DC link reactance, corresponds respectively to voltage-type and current mode topology such as electric capacity or inductance.Because need twice conversion, this current transformer is called as the two-stage inverter sometimes, and conversion is from the three-phase alternating current to the direct current for the first time, and conversion is to export from the direct current to the three-phase alternating current for the second time.Its output AC variable voltage and variable frequency.

Yet because need twice power conversion, the energy conversion efficiency of traditional two-stage current transformer is lower than the single-stage conversion.Directly the AC/AC current transformer designs at efficient, and for example three-phase input AC energy is directly delivered to three-phase output voltage in the AC/AC matrix converter.Yet three-phase AC/AC matrix form current transformer needs 18 power switch pipes, needs complicated reversing switch control simultaneously and absorb circuit to occur to avoid input side short circuit and outlet side open circuit situation.For so-called sparse matrix converter has appearred in the quantity that reduces switching tube, this converter is revised matrix converter, adopt AC-to DC and direct current to exchanging the two-stage power conversion in fact, embodied the compromise balance between traditional two-stage AC/DC/AC current transformer and the AC/AC matrix form current transformer.This sparse matrix current transformer need not the DC side perceptual device, PWM switch control by particular design, can reduce the switching loss of input side switch, yet last the comparing with two-stage AC/DC/AC current transformer of sparse matrix current transformer design needs extra three switching devices and six extra diodes.Compare with the matrix form current transformer, the sparse matrix current transformer has reduced the quantity of switching tube, but sacrificed efficient, therefore, need a kind of improved electric energy current transformer to design the AC energy that is converted to second kind of form efficiently from a kind of AC energy of form, need not a large amount of switching tubes and complicated switch control simultaneously.

Summary of the invention

The objective of the invention is for overcoming the weak point of prior art, a kind of AC to AC converter is proposed, the present invention can use a spot of asymmetric device for power switching to convert input AC power to output AC power under the operational mode with frequency or frequency conversion, energy can two-way flow, promptly also can convert the AC power that input connects from the AC power that output connects to.

The present invention proposes an AC to AC converter, it is characterized in that, this current transformer comprises:

A three-phase alternating current input connection has the first, the second and the 3rd AC input terminal to receive or to provide the three-phase alternating current input power;

A three-phase alternating current output connection has the first, the second and the 3rd ac output end to provide or to receive the three-phase alternating current electric output power;

A DC circuit comprises first and second dc terminals and stored energy assembly;

A switching network comprises altogether, and nine switching devices form three bridge arm circuit, each bridge arm circuit has three switching devices, each bridge arm circuit is connected to corresponding AC input terminal and corresponding ac output end, each bridge arm circuit comprises first switching device and is connected to corresponding AC input terminal and first dc terminal, second switch is connected to corresponding AC input terminal and corresponding ac output end and the 3rd sub and second dc terminal of ac output end that switch is connected to correspondence; And

A control system is connected to switching network, is provided as that input AC electrical power that the switching device switch controlling signal connects to input in the future is transformed into the output AC electrical power that output connects or the input AC electrical power that connects to output in the future is transformed into the output AC electrical power that input connects.

For invention being done basic understanding, special summary one or more features of the present invention are as follows:

The summary here is not to inventing comprehensive commentary, and its purpose neither be determined scope of invention neither show the specific factor of invention.The main purpose of summary is some concise and to the point notions that proposed invention before describing in detail.

Proposed invention relates to the bi-directional conversion of energy between single-phase or three-phase system AC to AC, the middle DC circuit that adopts, and be applied to any power conversion occasion, comprise being not limited to UPS line voltage adjuster, voltage restorer, motor-driven, with special application of power, wherein output can provide variable voltage or/and variable frequency, or fixed voltage and frequency.

One or more features according to invention, one nine pipe three-phase alternating current has been proposed to AC convertor, adopt nine switches to form three bridge arm circuit in the topological network, three switches of each brachium pontis wherein, be used for the interchange power output of handle at Cheng Zaisan the output of input AC power transfer of three inputs, otherwise or.Bridge arm circuit is connected to corresponding input and output terminal separately, first switch is connected between input terminal and first dc terminal, second switch is connected between input terminal and the lead-out terminal, and the 3rd switch is connected between lead-out terminal and second dc terminal.A control system is transformed into the output AC power that connects in output for the input AC electrical power that switch provides signal to be used for coming from the input connection, otherwise or.In a concrete realization, for providing a cover signal, each bridge arm circuit optionally make bridge arm circuit be in one of three kinds of states, these three kinds of states comprise that first kind of state is that input and output terminal with correspondence is connected on first dc terminal, during second kind of state the input and output terminal is connected to second kind of dc terminal, the third state is that input terminal is connected to first dc terminal, and lead-out terminal is connected to second dc terminal.Here switch controlling signal can provide according to the principle that makes the lead-out terminal terminal voltage that is connected to each bridge arm circuit be less than or equal to the input terminal terminal voltage on the same brachium pontis.When a certain specific implementation, utilize sine wave pulse width modulated method or space vector modulating method that control signal is carried out pulse width modulation by control system, but the input AC electrical power that control system provides switch controlling signal to be used to change comes from input to transformation or/and the output AC electrical power of frequency conversion, otherwise or.In addition, used switching tube can be an asymmetric device blocking voltage in one direction, allows the electric current two-way flow simultaneously.

One or more further feature of the present invention is relevant to AC convertor with nine pipe three-phase alternating currents, wherein have comprise totally nine can unidirectional blocking voltage permission bi-directional current flow a switching network of switching device.Current transformer has a control system to be connected to switching network to be used for the control switch device and to convert the electromotive power output that connects at three terminals of output to coming from the input AC electrical power that three terminals of input connect, otherwise or.

In a possible realization, switching network is made of three bridge arm circuit, and wherein each bridge arm circuit has three switches, and each bridge arm circuit is connected to corresponding input and output terminal to last.In an example, control system selects first kind of state to be used to connect corresponding input and output terminal to first dc terminal for brachium pontis provides switching signal, second kind of state is used to connect input and output terminal to the second dc terminal, the third state is used to connect input terminal to first dc terminal, connects lead-out terminal to the second dc terminal.

Further feature of the present invention has proposed six devices, single phase alternating current (A.C.) is to AC convertor, wherein the single phase alternating current (A.C.) input connects first and second input terminal, single phase alternating current (A.C.) output is connected to first and second lead-out terminals, and a DC circuit is made up of first and second dc terminals and energy storage device.

A realization comprises that six switching devices form two bridge arm circuit altogether, comprise totally three switching devices in each bridge arm circuit, here each brachium pontis is linked corresponding an AC input terminal and corresponding ac output end, in this is realized, first switching device of each brachium pontis is connected between corresponding input end and first dc terminal, second switch is connected between input terminal and the lead-out terminal, the 3rd switch is connected between lead-out terminal and second dc terminal, the single phase alternating current (A.C.) input power that control system provides switch controlling signal will be connected to input is transformed into the interchange power output that is connected to output, or will convert the AC power that input connects from the AC power that output connects to.In addition, in a possible realization, switching network has comprised altogether can block the asymmetric switching device of unidirectional voltage permission electric current two-way flow for six, control system is connected to switching network and is used for the input AC electrical power that comes from the input connection is converted to the output AC electrical power that is connected to output, otherwise or.

Description of drawings

Figure 1A is the schematic diagram of one nine pipe of explanation three-phase alternating current to the exchange conversion system embodiment, has shown one or more features of invention.

Figure 1B is that one of explanation has single phase alternating current (A.C.) that six asymmetric switching devices connect into the doube bridge arm switch network schematic diagram to the exchange conversion system embodiment, has shown the further feature of invention.

Fig. 2 A is a part schematic diagram that derives from the single bridge arm circuit of current transformer among Figure 1A and the 1B, wherein, first switch is connected corresponding AC input terminal and first dc terminal, second switch is connected input terminal and corresponding ac output end, and the 3rd switch is connected lead-out terminal and second dc terminal.

Fig. 2 B is a form, demonstrate Figure 1A of embodiment, the switching manipulation of current transformer bridge arm circuit three-state among 1B and the 2A, be defined as: first state is connected to first dc terminal to the input and output terminal, second state is connected to second dc terminal to the input and output terminal, second state is connected to first dc terminal to input, and lead-out terminal is connected to second dc terminal.

Fig. 3 provides the input and output modulation waveform of an illustrated embodiment and the carrier waveform of sharing, and operates in same frequency (CF) operator scheme under the Sine Wave Pulse Width Modulation of different modulating ratio when the current transformer shown in Figure 1A and Figure 1B.

Fig. 4 sketches the contours of the input and output modulation waveform of an illustrated embodiment and the carrier waveform of sharing, frequency conversion (VF) operator scheme under the Sine Wave Pulse Width Modulation when the current transformer input and output carrier wave shown in Figure 1A and Figure 1B operates in modulation ratio and is 0.433.

Fig. 5 A and 5B are the diagrams of input and output on off sequence waveform, are that the Sine Wave Pulse Width Modulation of the embodiment in a single pulse width modulation cycle of the current transformer shown in Figure 1A and Figure 1B realizes.

Fig. 6 be a part schematic diagram provided the affectionately wide modulation of the current transformer embodiment sine wave shown in Figure 1A and Figure 1B realize in the converter switches control system in order to produce the logical circuit of three switching device drive signals of any bridge arm circuit of current transformer.

Fig. 7 illustrates a cover input and output signal of the logical circuit shown in Figure 6 of the current transformer shown in Figure 1A and Figure 1B.

Fig. 8 illustrate one be enclosed within one realized the three-phase alternating current shown in Figure 1A to AC convertor with the embodiment bridge arm circuit gate driver switching signal in the experiment of operational mode frequently.

Fig. 9 illustrates at one and has realized that the three-phase alternating current shown in Figure 1A is to the input and output current waveform of AC convertor with the embodiment in the experiment of frequency operational mode.

Figure 10 A and 10B illustrate respectively one realized the three-phase alternating current shown in Figure 1A to AC convertor with input and output line voltage and phase current curve in the experiment of operational mode frequently.

Figure 11 A illustrates at one to 11C and has realized that the three-phase alternating current shown in Figure 1A is leading with the correspondence of frequency operational mode to AC convertor, input phase voltage in the experiment under unit and the lagging power-factor operational mode and phase current curve.

Figure 12 illustrate one realized the three-phase alternating current shown in Figure 1A to AC convertor with input phase voltage and output current phase curve in the experiment of operational mode frequently, can realize the voltage recovery operation to show when input voltage descends, to export.

Figure 13 A illustrates at one and has realized that the three-phase alternating current shown in Figure 1A arrives the input and output phase voltage waveform in the experiment of AC convertor frequency conversion (VF) operational mode.

Figure 13 B illustrates at one and has realized the input and output line voltage waveform of the three-phase alternating current shown in Figure 1A in the experiment of AC convertor converting operation pattern.

Figure 14 A illustrates at one and has realized input line voltage and the input current waveform of the three-phase alternating current shown in Figure 1A in the experiment of AC convertor converting operation pattern.

Figure 14 B illustrates at one and has realized output line voltage and the output current wave of the three-phase alternating current shown in Figure 1A in the experiment of AC convertor converting operation pattern.

Figure 15 illustrates at one and has realized input phase voltage and the phase current waveform of the three-phase alternating current shown in Figure 1A in the experiment of AC convertor converting operation pattern.

Figure 16 illustrates at one and has realized the input and output phase current waveform of the three-phase alternating current shown in Figure 1A in the experiment of AC convertor converting operation pattern.

Figure 17 A and Figure 17 B illustrate at one and have realized input and output line voltage and the phase current waveform when output frequency is undergone mutation in the experiment of AC convertor converting operation pattern of the three-phase alternating current shown in Figure 1A.

Embodiment

Following description and accompanying drawing have been set forth realizing in detail intuitively of some invention, only show several embodiment implementations that inventive principle is possible, yet, be not that invention is a plurality of in the cards exhaustive.Other purpose of invention, if advantage is relevant with accompanying drawing with new features, with specifically setting forth in the description to invention below, wherein:

Figure 1A shows the embodiment of one nine pipe AC to AC power converter or power converter, one or more features of invention are described, the power converter of present embodiment or power converter 10 comprise that a three-phase alternating current input connects or circuit 20 has AC input terminal 20a, 20b, and 20c (terminal A, B, and C) is used for receiving the three-phase alternating current input electric power from a three-phase input power supply 70, or provide the three-phase alternating current electrical power to three-phase input power supply 70, and the output of three-phase alternating current connects or circuit 30 has lead-out terminal 30a, 30b, and 30c (R, S, and T) is used to provide the three-phase alternating current electromotive power output to threephase load 80, or, also have a DC circuit 40 to comprise for example dc capacitor C of terminal 40a and 40b (P and N) and store energy assembly from threephase load 80 reception three-phase alternating current energy _DC, for example in, the input power supply 70 in schematic diagram, be expressed as three-phase alternating current potential source V _AS, V _BS, and V _CSWith input terminal A, B and C are by series connection resistance sense impedance component L _SA, R _SA, L _SB, R _SB, and L _SC, R _SCConnect respectively.While power supply V _AS, V _BS, and V _CSWith " Y " the type connected mode is connected to a common mid point or node " 0 ", though the three-phase alternating current of any kind input power supply 70 can be linked input 20.Output connects 30 terminal R, and S and T can link the threephase load 80 of any kind, among Figure 1A example be three loads with " Y " the type connected mode is connected to a common mid point " m ", and the loading liquifier in the example is shown inductance L _LRAnd resistance R _LRSeries load is connected to output R phase, inductance L _LSAnd resistance R _LSSeries load is connected to output S phase, inductance L _LTAnd resistance R _LTSeries load is connected to output T phase, though the current transformer in the invention can be for comprising any type electric of three phase alternating current motor.

System 10 comprises that also one nine pipe switching network 50 comprises three bridge arm circuit 52a of nine switching device S formation altogether, 52b, and 52c.Each bridge arm circuit comprises three switch S altogether, and this moment, circuit 52a comprised the first, the second and the 3rd switch S respectively _A1, S _A2, and S _A3, circuit 52b comprises the first, the second and the 3rd switch S respectively _B1, S _B2, and S _B3, circuit 52c comprises the first, the second and the 3rd switch S respectively _C1, S _C2, and S _C3Each bridge arm circuit 52 is connected on the positive and negative terminal 40a and 40b of DC circuit 40, and also be connected to a corresponding AC input terminal and corresponding ac output end, here first bridge arm circuit 52a is connected to input terminal A 20a and lead-out terminal R 30r, second bridge arm circuit 52b is connected to input terminal B 20b and lead-out terminal S 30s, and the 3rd bridge arm circuit 52c is connected to input terminal C 20c and lead-out terminal T 30t.

And shown in Figure 1A, each bridge arm circuit comprises first switching device (S _A1, S _B1, S _C1) be connected corresponding input terminal (A, B, C) and first dc terminal P 40a, second switching device (S _A2, S _B2, S _C2) be connected corresponding input terminal and corresponding lead-out terminal (R, S, T) and the 3rd switching device (S _A3, S _B3, S _C3) be connected lead-out terminal and second dc terminal 40b (N).The switching device S of any kind can be used to select first state to be electrically connected, second state electrical isolation, for example GTOs, IGBTs, IGCTs, (IEGT) or the like (being IGBTs in illustrated example), in illustrated example, single switch device S has comprised inverse parallel diode D _A1-D _A3, D _B1-D _B3, and D _C1-D _C3, so the voltage blocking ability of switching device is unidirectional or asymmetric, in servicely can only allow the electric current two-way flow at a direction blocking voltage, though the not requirement of strictness of invention itself.

Nine manage current transformers 10 comprises that also a control system 60 is connected with switching network 50, for switching device S provides switch controlling signal SC the input AC electrical power that connects 20 from input is converted in the output AC electrical power of importing connection 30.The control system 60 of any type can be used, and logic for example is based on the circuit of processor, based on the circuit of programmable logic chip CPLD or FPGA, software, firmware, software and hardware combining or the like.For optionally console switch S is with the conversion of control AC to AC, system 60 adopts pulse width modulation (PWM) method to provide three cover switch controlling signal SC to switching network 50 in the example.In illustrated embodiment, first control signal sequence SC _A1, SC _A2, and SC _A3Offer the switch S of the first cover bridge arm circuit 52a respectively _A1, S _A2, and S _A3, second control signal sequence SC _B1, SC _B2, and SC _B3Offer the switch S of the first cover bridge arm circuit 52b respectively _B1, S _B2, and S _B3, the 3rd control signal sequence SC _C1, SC _C2, and SC _C3Offer the switch S of the 3rd cover bridge arm circuit 52c respectively _C1, S _C2, and S _C3Be further described below Fig. 2 A and 2B, in example 3-phase power converter 10, the signal of one of three kinds of states is used for input AC power being changed at lead-out terminal R the power output of S and T.In addition, though discuss under the background of power conversion at folk prescription, the current transformer in the invention can be used for the bi-directional conversion energy.Wherein output connection 30 can be exchanged into reception input electric energy, and input connects 20 can be used for the output AC energy.

Another feature according to proposed invention, Figure 1B illustrates another kind of embodiment AC to AC converter 110, the unidirectional realization of this six pipes receives sinusoid from power supply 170 and exchanges input electric power, or provide single-phase electricity power to power supply 170, provide electromotive power output to single-phase load 180, or receive single-phase electricity power from single-phase load 180.Single-phase converter 110 comprises that a single phase alternating current (A.C.) input connection 120 has first and second

AC input terminal

120a and 120b (A and B) is used for receiving or provide the single phase alternating current (A.C.) input electric power from power supply 170.Here embodiment power supply 170 is an alternating-current voltage source V _ASThe power supply inductance L of connecting _SAWith a series resistance R _SASingle-phase converter 110 comprises that a single phase alternating current (A.C.) output connection 130 has first and second sub-130r of ac output end and 130s (R and S) provides or receive single-phase electricity power from load, and embodiment load 170 is an inductance L _LRAnd resistance R _LRSeries load can be used though comprise any single-phase load of monophase machine.Provide a DC circuit 140 to comprise first and second dc terminal 140a (P) and 140b (N) and stored energy assembly (capacitor C in addition _DC), also have the switching network 150 of six pipes to have a pair of three pipe

bridge arm circuit

152a and 152b.

As in above-mentioned 3-phase power converter 10, six switching device S are the IGBTs that have the inverse parallel diode in single-phase converter 110, have the characteristics of unidirectional blocking voltage and bi-directional current flow, and each bridge arm circuit 152 comprises 3 switching device S.Each bridge arm circuit 152 is connected to the AC input terminal (A or B) and corresponding ac output end (R or S) of a correspondence in addition, and comprises first switching device (S _A1Or S _B1) connection corresponding input end (A, B) with first dc terminal 140a (P), second switching device (S _A2Or S _B2) connect corresponding input end (A, B) and lead-out terminal (R, S), the 3rd switch (S _A3, S _B3) (R is S) with second dc terminal 140b (N) to connect lead-out terminal.PWM on-off control system 160 connects doube bridge arm switch networks 150 and provides switch controlling signal SC to be used for from connecting the output AC electrical power that 120 input power converts output connection 130 to switching device S, otherwise or.

In Fig. 2 A and 2B, three-phase and single-phase converter 10,110 bridge arm circuit 52,152, and a cover switch controlling signal SC who is produced can be to be converted into output AC with the similar mode of the single-phase bridge arm circuit of in embodiment system 10,110 each 52,152 with input AC power, otherwise or, can be operated in frequency (CF operational mode input and output frequency is identical) or under change output frequency (VF operational mode output frequency can change with respect to incoming frequency) pattern.Fig. 2 A illustrates an embodiment brachium pontis 52a, and 152a comprises the switch S that connects into Figure 1A and 1B mode _A1-S _A3, first input and output terminal A that bridge bi is corresponding with difference is connected with R, and connects dc terminal P and N, and wherein other bridge arm circuit 52,152 is constructed in a similar fashion.Burst SC from the correspondence of control system 60,160 comprises signal SC _A1, SC _A2, and SC _A3Be connected respectively to bridge arm circuit 52a, the first, the second and the 3rd switching device S of 152a _A1, S _A2, and S _A3, bridge arm circuit 52,152 connected modes of other in the embodiment current transformer 10,110 and carrying out below with the three condition switch operational mode and first bridge arm circuit 52a that mention, 152a and switch controlling signal thereof are similar.The embodiment bridge arm circuit 52a that form 200 explanations that Fig. 2 B shows are realized by the control system in the current transformer shown in Figure 1A 10,110 60,160, the three condition switching manipulation of 152a.Form 200 has defined the corresponding switch S of first state _A1And S _A2Conducting, S _A3Shutoff is to connect input and output terminal A and R to first dc terminal P, second corresponding switch S of state _A1Turn-off S _A2And S _A3Conducting is to connect input and output terminal to the second dc terminal, the 3rd the corresponding switch S of state _A1And S _A3Conducting, S _A2Shutoff is to connect input terminal A to dc terminal P, and lead-out terminal is to dc terminal N.

At the 3-phase power converter 10 of Figure 1A, introduce bridge arm circuit 52 and control system 60 different concepts below, wherein also operation in a similar manner of the single-phase realization 110 of Figure 1B with the explanation invention.When current transformer 10 operations of Figure 1A, three-phase input current I _A, I _B, and I _CWith output current I _R, I _S, and I _TBe subjected to input terminal A respectively, B and C and lead-out terminal R, the voltage control of S and T, the controlled again 60 control switch control signal SC of system of terminal voltage are in one of three kinds of states showing among Fig. 2 B and control.By this way, the part of intake has been passed to DC circuit 40, be delivered to afterwards output 80, other energy by than the back-to-back current transformer quantity of tradition switch still less by from import 70 directly be transformed into output 80, otherwise or.In illustrated realization, pulse width modulating signal (PWM) SC that provides by control system 60 _A1, SC _A2, and SC _A3(and signal of other bridge arm circuit 52b and 52c), utilization is presented at the embodiment three condition switch solution shown in the form 200 among Fig. 2 B, the lead-out terminal voltage that makes each bridge arm circuit 52 connect is equal to or less than the input terminal on the same brachium pontis, here switch controlling signal SC can be provided by any switching technique, include but not limited to sine wave pulse width modulated or the space vector modulation (SVM) of embodiment among the figure, or other method of switching.As described below, illustrated switch solution is under the situation of output voltage smaller or equal to input voltage that keeps given bridge arm circuit, by add the control of the method utilization of different biasings or common-mode voltage for the input and output modulation waveform, allow the input and output phase voltage is controlled respectively to the brachium pontis on off state.And, as described below, provide switch controlling signal SC by control system 60, current transformer 10,110 can be operated in (CF) pattern frequently wherein the input AC electrical power connect 30 in output and be converted into output AC electrical power frequently, or frequency conversion (VF) pattern wherein the input AC electrical power connect the 30 output AC electrical power that are converted into frequency conversion in output, otherwise or.

Figure 21 0 and 250 shown in Fig. 3 and 4 has illustrated a kind of pulse-width modulation scheme of selecting for use for the on-off control system of nine switching device S of control current transformer 10.Generally speaking, different modulation waveforms is used in input and output separately, and carrier waveform is identical to produce switch controlling signal SC, and at this moment, the amplitude of modulation waveform and frequency determine or controlled the amplitude and the frequency of the input and output waveform of being modulated.Image 210 among Fig. 3 has represented that embodiment input and output modulation waveform is respectively 220 and 240, with a common triangular carrier modulation waveform 230, be used for representing under the different modulating coefficient (MI) that Figure 1A and 1B current transformer 10,110 are in sine wave pulse width modulated with (CF) operational mode frequently.

And, in illustrated switching network design, need prevent that the lead-out terminal voltage in arbitrary bridge arm circuit 52 from surpassing input terminal voltage.Therefore, embodiment pulse width modulating switch controlling schemes has been introduced biasing or DC common mode component guaranteeing to import phase voltage A, and the modulation waveform 220 of B and C (for example, Vma, Vmb is Vmc) at input phase voltage (V _AN, V _BN, V _CN) excursion in always greater than (or to equaling) output phase R, all possible output phase voltage (V of S and T _RN, V _SN, V _TN) corresponding output modulation waveform 240 (for example, Vmr, Vms, and Vmt) guarantees that like this input voltage on each bridge arm circuit is always more than or equal to output voltage, and, the input and output of embodiment modulation same-phase (on the time), adopting same carrier waveform is embodiment triangular carrier 230V in Fig. 3 and 4 _CrFigure 250 among Fig. 4 has shown the embodiment input and

output modulation waveform

220 and 240 when modulation ratio MI is 0.433, add that carrier waveform 230 produces current transformer 10 among Figure 1A and the 1B, 110 sine wave pulse width modulated when being operated in frequency conversion (VF) pattern, this moment, the output AC frequency was different from (being higher than) incoming frequency.

In this sine wave pulse width modulated realized, each modulation waveform 220,240 was all compared with carrier waveform 230, and produces the input and output waveform of current transformer 10 with this, and any suitable pulse-width modulation scheme can be applied to invention.For example can utilize wave generator circuit to produce the modulation and the carrier waveform 220 of Fig. 3 and 4 expressions, 230,240, add different bias voltage circuits and two comparison circuits come with

single modulation signal

220 and 240 and carrier wave 230 relatively send into logical circuit to produce signal, the embodiment that Fig. 6 has provided logical circuit is a logical circuit 300.In addition, pulse width modulation can use the method based on processor to realize, and illustrated modulation waveform (carrier waveform), and biasing and comparison can be used software, and firmware or other Digital Logic realize.At the same frequency of current transformer 10 or frequency-changing AC in ac operation, control system 60 provides positive direct current offset for input modulation waveform 220, for output modulation waveform 240 provides negative direct current offset, the numerical value of these skews or biasing can be that the output voltage on any bridge arm circuit 52 that prevents that any way is realized surpasses input voltage.In illustrated system 10, different pulse width modulating schemes adopts different skews, these skews can change along with the variation of the input and output index of modulation, or change according to moment difference, also can operate in frequency or variable mode difference according to current transformer 10 to become.

Illustrated with frequently realize (for example, Fig. 3) in, input and

output modulation waveform

220 and 240 decides level deviation according to mutual phase difference, to prevent that exporting modulation waveform 240 surpasses input modulation waveform 220.In this case, show that input modulation waveform 220 (for example, to three-phase input waveform Wma, Wmb, and Wmc) is determined by following formula (1) as Fig. 3 and 4 embodiment waveforms:

Vm _INPUT＝Vd-Vip+VipSINθ， (1)

Here Vd is C _DCBetween DC circuit voltage (Figure 1A) Vip the time any time input modulation waveform peak value, three-phase A wherein, the modulation waveform of B and C differs from 120 degree (being that 180 degree differ to single-phase converter 110 for example) mutually.Exporting modulation waveform 240 (for example waveform Wmr, Wms, and Wmt) is in addition determined by following formula (2):

Vm _OUTPUT＝Vop+VopSINθ， (2)

Here the peak value of Vop time output modulation waveform any time, three-phase A wherein, the modulation waveform of B and C differs from 120 degree (being that 180 degree differ to single-phase converter 110 for example) mutually.In this, the inventor considers that the minimum value of the different required direct voltage Vd of input and output phase difference with the frequency operational mode time can change, and preferably can limit the phase difference that be input to output when realizing this moment.

In the frequency conversion (VF) of an embodiment 3-phase power converter 10 realizes (for example Fig. 4), the direct current offset of input modulation waveform 220 (for example, waveform Wma, Wmb, and Wmc) is provided by following formula (3):

(3Vd/4)+VipSINθ ₁， (3)

Output modulation waveform 240 (for example waveform Wmr, Wms, and Wmt) can be provided by following formula (4):

(Vd/4)+VopSINθ ₂， (4)

Here θ ₁And θ ₂Can change with different frequency.Shown in Fig. 3 and 4, minimum input modulation waveform 221 and maximum output modulation waveform 246 are curves, but adopt above-mentioned biasing like this, and input modulation waveform 220 is always more than or equal to output waveform 240 in the embodiment pulse-width modulation scheme.

The illustrated control system 60 of Fig. 5 A and 5B has realized embodiment sine wave pulse width modulated on off sequence in controller 60, this sequence can be divided into 7 switches or commutation section (each switching mode is 7 sections sequences in the cycle) in each PWM cycle.Fig. 5 A illustrates embodiment figure 260. Fig. 5 B and illustrates figure 270, and the embodiment situation has provided frequency when carrier wave 230 much larger than switch periods scope situation of modulation waveform 220,240 typical cases.Here with input modulation waveform Vma, Vmb and Vmc and output waveform Vmr, Vms and Vmt are that constant is an example to figure 260 and 270 for convenience of description, the also available 5 sections methods of pulse width modulation, and 3 sections methods or other method realize.

And with required input and output waveform V _AN, V _BN, V _CN, and V _RN, V _SN, V _TNBe presented at figure 260 and 270 respectively, when the modulation waveform of correspondence was higher than carrier wave 230, actual input and output waveform was high, the width of the input and output waveform of Xu Yaoing just depends on modulation and carrier waveform like this, and the input and output modulator 220 of three-phase and 240 can carry out phase shift accordingly.Like this, for example use the comparator circuit (not shown) or adopt software, can obtain the input and output waveform by input and output modulation waveform 220,240 is separately compared with carrier wave 230.In Fig. 5 A illustrated embodiment, required first imports V mutually _ANFrom moment TI1 to TI6 is high, V _BNBe high from TI2 to TI5, V _CNBe high from TI3 to TI4.

Similarly, the required V of the output pattern 270 of Fig. 5 B _RNFrom moment T01 to T06 is high, V _SNBe high from T02 to T05, V _TNBe high from T03 to T04.

Fig. 6 and 7 shows each bridge arm circuit, and a logical circuit 300 (Fig. 6) can be provided, and corresponding brachium pontis input and output desired signal waveform during its input (is required brachium pontis input V to first brachium pontis 52a for example, _ANWith brachium pontis output V _RN), the switch controlling signal SC that its output produces corresponding to bridge arm circuit 52 (is SC to first brachium pontis 52a for example, _A1, SC _A2, and SC _A3).Here each bridge arm circuit 52 needs independent circuit 300.As an alternative, the defined function of logic that is used for driving the circuit 300 of bridge arm circuit 52 can be with firmware, and modes such as software realize.The picture 320 of Fig. 7 has shown the first cover embodiment switch controlling signal SC _A1, SC _A2, and SC _A3, produce 7 switch segments S1-S7 (the S3-S5 section is a state 1) in the switch periods of switching logic in shown Fig. 5 A to 7 that control system 60 provides here and occur different on off

state

2,3,1,3 and 2 respectively.

Example among Fig. 5 A-7 has shown the sine wave pulse width modulated method that is used for Figure 1A 3-phase power converter 10, also can be applied in the single-phase realization 110 of Figure 1B according to this method of invention.Other the sinusoidal wave PWM method that modulation waveform is carried out one or more modifications also can be used, such as, when the triple-frequency harmonics composition adds basic or first-harmonic sinusoid, synthetic waveform (is for example modulated with carrier wave, triangular wave or other), here all so change the scope that the equivalents that all is considered to the sinusoid pulse width modulation modulation is included patent in, and no matter whether modulation waveform is pure sinusoidal shape.And, other pulse modulation technology also can use, such as, the on off state sequence that space vector modulation (SVM) produces or the generation of pattern define in three dimensional vector diagram with reference to rotating vector by one, adopt specific pattern or status switch, the corresponding vector duration is determined in position according to present reference vector, guarantees that by selecting suitable on off state and duration to calculate the input terminal voltage of each bridge arm circuit 52 is equal to or higher than corresponding output end voltage.And, current transformer 110 such single-phase realizations among the image pattern 1B can realize by the pulse width modulation or other the switching technique of equivalence, the switching signal sequence of two bridge arm circuit need differ 180 degree each other, makes the lead-out terminal voltage of single bridge arm circuit 152 be equal to or less than corresponding input end by suitable modulation biasing or adjustment.

In Fig. 8-17, the three-phase alternating current shown in Figure 1A has carried out with the experiment of (CF) pattern and frequency conversion (VF) pattern frequently to the model machine of a 7.5KVA of AC convertor.In the experiment, the effective value of input line voltage (V for example _AB) be 208V, power supply inductance L s is 2.5mH, and output loading is the three-phase resistance inductive load, and resistance is 14.6 ohm, and inductance is 2.5mH, dc capacitor C _DCCapacitance is 2350 μ F, and adopting sample frequency fsw is 3.24kHz space vector modulation PWM scheme.The input supply frequency is 60Hz, and input side uses the voltage oriented closed-loop vector control system of line with control input side electric current, and input side adopts switching voltage control.In service at the same frequency (CF) of being tested, the input and output voltage waveform is near homophase, and DC circuit voltage Vd remains on about 360V, and the corresponding input and output index of modulation is about 0.8.

With frequency the time, figure 400 has shown the embodiment bridge arm circuit switch gate electrode drive signals SC on a cover current transformer 10 experimental provisions among Fig. 8 _A1, SC _A2, and SC _A3Figure 410 has shown embodiment input and output current waveform I respectively among Fig. 9 _AAnd I _R, with frequently in service, the input and output current waveform is near sinusoidal wave at current transformer 10, and output current has very little lagging power-factor.Figure 10 A and 10B have provided figure 420 and 430 respectively, demonstrate input and output line voltage (V respectively _ABAnd V _RS) and phase current figure (I _AAnd I _R) experimental waveform, at the waveform that all comprises same DC circuit voltage Vd with input and output line voltage waveform in service frequently.There is figure 440,450 and 460 to show that respectively corresponding input side is leading when experimental provision moves with frequency among Figure 11 A-11C, under the situation of unit and lagging power-factor, input line voltage and phase current (V _ASAnd I _A).Graphical display among Figure 11 A-11C embodiment test the ability that current transformer 10 has the input side Adjustable Power Factor Current, and the variation of input power factor is to not influence of output power factor, shows the requirement that the converter system 10 invented can the load of adaptive compensation low power factor.Input line voltage and output current phase have been shown respectively in the figure 470 shown in Figure 12, have shown when input voltage descends that system 10 has regulating power can keep output current I _R

To frequency conversion (VF) operational mode, the embodiment performance of AC to AC converter is presented among Figure 13 A-17, and wherein input and output modulation ratio all is about 0.4.Figure 13 A has comprised that figure 500 demonstrates input and output phase voltage curve V respectively _ANAndV _RN, { incoming frequency is 60Hz.Figure 510 among Figure 13 B demonstrates input and output line voltage curve (V _ABAnd V _RS), as can be seen, incoming frequency is 60Hz, output frequency is 30Hz.Figure 13 A can clearly find out, even output voltage amplitude and frequency change output voltage V _RNAlways be less than or equal to input voltage V _ANFigure 14 A and 14B show input and output line voltage and phase current curve V respectively _AB, I _A, V _RS, and I _R, output frequency also is 30Hz here.Figure 540 among Figure 15 demonstrates input phase voltage and phase current curve V respectively _ASAnd I _A

Figure 16 has provided figure 550 and has demonstrated input and output phase current I under the different frequency of current transformer 10 respectively _AAnd I _RThe figure 560 of Figure 17 A and the figure 570 of Figure 17 B have shown that respectively embodiment is as output frequency input and output line voltage V the 3-phase power converter 10 when 120Hz changes to 30Hz _ABAnd V _RS, and the input and output electric current I _AAnd I _R, regulate when dynamic input current and voltage waveform I when output frequency this moment _AAnd V _ABBasically be not subjected to disturbance.Like this, invention can be found multiple application, comprise requirement with Variable Amplitude or/and frequency conversion rate mode is changed input AC power to output AC power, but do not need the cost as back-to-back current transformer or matrix form current transformer, volume, and complexity.The present invention only needs nine switching devices to change three-phase AC power, and six switching devices are changed single phase alternating current (A.C.) power.

The foregoing description only is used for showing the many aspects several possible realization wherein of proposed invention, and after reading and having understood this explanation and accompanying drawing, the variation of equivalence and/or other people who revises the industry are conspicuous.Especially to (gathering about above-described assembly, device, switching device, system, circuit, with similar) performed various functions, the term (comprising quoting " method ") that is used for describing this assembly also can be used for describing any assembly, unless noted otherwise, hardware for example, software, or both combinations, as long as can finish the specific function (that is to say, on the function equivalence) of described assembly, even and the functional structure of finishing that in the invention diagram realizes, discloses out structurally inequivalence is also effective.

In addition, though certain feature of invention only disclose with one in several realizations, these features can with one or more further features of other realization in conjunction with after may satisfy any given or specific application and have advantage.And, " comprise " for detailed description and/or the term in requiring, " having ", " having ", " having ", or other variation are with " comprising " synonym.

Claims

1. an AC to AC converter is characterized in that, this current transformer comprises:

A control system is connected to switching network, be provided as the input AC electrical power that the switching device switch controlling signal connects to input in the future and be transformed into the output AC electrical power that output connects, or the input AC electrical power that connects to output in the future is transformed into the output AC electrical power that input connects.

2. current transformer as claimed in claim 1, it is characterized in that, described control system provides three cover switch controlling signals for switching network, every suit offers a corresponding bridge arm circuit, control system is controlled every cover switch controlling signal and is in a kind of in three kinds of states, comprise that first state connects corresponding input and output terminal to first dc terminal, second state connects input and output terminal to the second dc terminal, be connected input terminal with the 3rd state to first dc terminal, connect lead-out terminal to the second dc terminal.

3. current transformer as claimed in claim 2, it is characterized in that, described every suit switch controlling signal comprises first, second, be connected respectively to first of corresponding brachium pontis with the 3rd switch controlling signal, second, the 3rd switching device, definition first and second each switching device conductings, the 3rd switching device turn-offs and is first state, and first switching device turn-offs, and second and the 3rd switching device conducting is for being second state, first and the 3rd switching device conducting, it is the 3rd state that second switching device turn-offs.

4. current transformer as claimed in claim 1, it is characterized in that, described control system provides three cover switch controlling signals to be connected to switching network, every suit is used to control a corresponding bridge arm circuit, every suit in the switch controlling signal comprises first, second and the 3rd switching signal is connected respectively to first on the corresponding brachium pontis, second and the 3rd switching device, first and second each switching device conductings, the 3rd switching device turn-offs and forms first state, and first switching device turn-offs, and second and the 3rd switching device conducting forms second state, first and the 3rd switching device conducting, second switching device turn-offs and forms the 3rd state.

5. current transformer as claimed in claim 1 is characterized in that, described switch controlling signal provides the lead-out terminal voltage to remain connected to each bridge arm circuit to be equal to or less than the input terminal that is connected on the same bridge arm circuit by control system.

6. current transformer as claimed in claim 1 is characterized in that, described switch controlling signal utilizes sine wave pulse width modulated or space vector modulating method pulse width modulation to form by control system.

7. current transformer as claimed in claim 1, it is characterized in that, the input AC electrical power that described control system provides switch controlling signal to connect from input is transformed into same frequency or the frequency conversion output AC electrical power that output connects, and the input AC electrical power that connects from output is transformed into same frequency or the frequency conversion output AC electrical power that input connects.

8. current transformer as claimed in claim 1 is characterized in that, described switching device can only folk prescription to blocking voltage, allow the electric current two-way flow.

9. an AC to AC converter is characterized in that, this current transformer comprises:

A three-phase alternating current input connection has the first, the second and the 3rd AC input terminal to receive or to provide the three-phase alternating current input power:

A three-phase alternating current output connection has the first, the second and the 3rd ac output end to provide or to receive the three-phase alternating current electric output power:

A DC circuit comprises first and second dc terminals and a stored energy assembly;

A switching network comprises nine switching devices altogether, this device can only folk prescription to blocking voltage, allow the electric current two-way flow, this switching network is connected to so-called interchange input and output and connects and so-called DC circuit;

Control system is connected with switching network and is used for the control switch device and converts the output AC electrical power that output connects to coming from the input AC electrical power that input connects, or converts the output AC electrical power that input connects to coming from the input AC electrical power that output connects.

10. current transformer as claimed in claim 9, it is characterized in that, described switching network has three bridge arm circuit to constitute, each bridge arm circuit has three switching devices, each bridge arm circuit is connected to the AC input terminal of a correspondence and ac output end of a correspondence, (first and second each dc terminals), control system provides three cover switch controlling signals for switching network, every suit offers a corresponding bridge arm circuit, control system is controlled every cover switch controlling signal and is in one of three kinds of states, comprise that first state connects corresponding input and output terminal to first dc terminal, second state link input and output terminal to the second dc terminal, be connected input terminal with the 3rd state to first dc terminal, connect lead-out terminal to the second dc terminal.

11. current transformer as claimed in claim 10 is characterized in that, its current potential of lead-out terminal that described control system control switch device keeps linking in each bridge arm circuit is equal to or less than the input terminal that is connected to same brachium pontis.

12. current transformer as claimed in claim 9 is characterized in that, described control system provides the pulse width modulating switch control signal for switching network, with sine wave pulse width modulated or space vector modulating method control switch device.

13. current transformer as claimed in claim 9, it is characterized in that, described control system provides switch controlling signal to come from the input AC electrical power that input connects with control and has changed into the frequency conversion output AC electrical power that connects in output, or control comes from the input AC electrical power that output connects and changes into the frequency conversion output AC electrical power that connects in input.

14. an AC to AC converter is characterized in that, this current transformer comprises:

The input of single phase alternating current (A.C.) connects and has first and second AC input terminal to receive or to provide the alternating current input power;

A single phase alternating current (A.C.) output connection has first and second ac output end to provide or to receive the single phase alternating current (A.C.) electric output power;

A switching network comprises that six switching devices form two bridge arm circuit altogether, each bridge arm circuit has three switching devices, each bridge arm circuit is connected to corresponding AC input terminal and corresponding ac output end, each bridge arm circuit has comprised first switching device and has connected corresponding AC input terminal and first dc terminal, second switch connects corresponding AC input terminal and ac output end, is connected corresponding ac output end and second dc terminal with the 3rd switch; And a control system is connected to switching network, export the output AC electrical power that connects for switching device provides switch controlling signal being transformed into, or will be transformed into the output AC electrical power of input connection from the input AC electrical power that output connects from the input AC electrical power that input connects.

15. current transformer as claimed in claim 14, it is characterized in that, described control system provides two cover switch controlling signals to switching network, every suit offers a corresponding bridge arm circuit, control system control every suit switch controlling signal is in one of three kinds of states, comprise that first state connects the input and output terminal to first dc terminal, second state connects input and output terminal to the second dc terminal, be connected input terminal with the 3rd state to first dc terminal, connect lead-out terminal to the second dc terminal.

16. current transformer as claimed in claim 14 is characterized in that, described control system provides the pulse width modulating switch control signal for switching network, with sine wave pulse width modulated or space vector modulating method control switch device.

17. current transformer as claimed in claim 14, it is characterized in that, described control system provides switch controlling signal will convert the frequency conversion output AC electrical power that connects in output from the input AC electrical power that input connects to, or will convert the frequency conversion output AC electrical power that connects in input from the input AC electrical power that output connects to.

18. current transformer as claimed in claim 1 is characterized in that, described switching device can only folk prescription to blocking voltage, allow the electric current two-way flow.

19. an AC to AC converter is characterized in that, this current transformer comprises:

A single phase alternating current (A.C.) input connection has first and second each AC input terminals to receive or to provide the single-phase alternating current input power;

A switching network comprises six switching devices altogether, and so-called switching device can only allow the electric current two-way flow at folk prescription to blocking voltage, and so-called switching network is connected to so-called interchange input and output and connects and so-called DC circuit; And

A control system is connected to switching network and will comes from the output AC electrical power that the input AC electrical power of importing connection is transformed into the output connection with the control switch device, and the input AC electrical power that maybe will come from the output connection is transformed into imports the output AC electrical power that connects.

20. current transformer as claimed in claim 19, it is characterized in that, described switching network comprises two bridge arm circuit, have three switching devices in each bridge arm circuit, each bridge arm circuit is connected to corresponding AC input terminal and corresponding ac output end, control system provides two cover switch controlling signals for switching network, every suit offers one of corresponding bridge arm circuit, control system control every suit switch controlling signal is in one of three kinds of states, comprise that first state connects corresponding each dc terminal of input and output terminal to the first, second state connects input and output terminal to the second dc terminal, be connected input terminal with the 3rd state to first dc terminal, lead-out terminal to the second dc terminal.

21. current transformer as claimed in claim 19 is characterized in that, described control system provides the pulse width modulating switch control signal for switching network, with sine wave pulse width modulated or space vector modulating method control switch device.

22. current transformer as claimed in claim 19, it is characterized in that, described control system provides switch controlling signal will come from the input AC electrical power of importing connection and has been transformed into the output AC electrical power that connects in output, and the input AC electrical power that maybe will come from the output connection is transformed into the output AC electrical power that connects importing.