CN203827191U - 3N+3 switch group MMC AC-AC converter - Google Patents

Abstract

The utility model provides a 3N+3 switch group modular multilevel converter (MMC) AC-AC converter comprising N three-phase alternating-current input/output units, a first bridge arm, a second bridge arm, a third bridge arm and a capacitor. Each of the first bridge arm, the second bridge arm, and the third bridge arm are formed by series connection of N+1 switch groups and two inductors; and each switch group is formed by series connection of n power switch units. Three terminals of each three-phase inductive load serve as three-phase alternating-current outputs. N is larger than 2; and n is a positive integer. According to the scheme, the converter employs the carrier phase-shifting PWM controlling mode. Each three-phase alternating-current output is converted into the alternating-current input whose line voltage is at the 2n+1 level; after AC-AC conversion, the alternating-current output with the line voltage at the 2n+1 level is obtained and is used for power supplying of loads. Moreover, the voltage stress that each switching tube bears in the MMC power switch unit is one one-nth of the direct-current power voltage. A voltage sharing problem of the switch tube can be solved. The provided converter can be applied to the high-voltage and high-power occasions.

Description

3N+3 switches set MMC AC-AC converter

Technical field

The utility model relates to module combination multi-level converter (MMC) field, is specifically related to a kind of 3N+3 switches set MMC AC-AC converter.

Background technology

, under this trend, there is the direction of two kinds of improvement rectifiers: reduce passive device or improve rectifier topology structure to reduce active device as the new development that reduces active device direction at present power rectifier forward miniaturization, high reliability and low-loss future development.Three-phase 3N+3 switch AC-AC converter has reduced 3N-3 switch and corresponding drive circuit with respect to traditional 6N switch converters, in the application of considering cost and volume, occupies certain advantage.But 3N+3 switch AC-AC converter Mei road input and output are three level, input and output AC wave shape is poor.In addition, the half that the voltage stress that in 3N+3 switch, each switch bears is DC bus-bar voltage, and there is the voltage-sharing of 3N+3 switching tube, this has limited the application of three-phase 3N+3 switch AC-AC converter in high pressure and large-power occasions greatly.

In recent years, multilevel technology is constantly promoted, and successful Application is at the industrial circle such as such as high voltage direct current transmission, Electric Drive, active power filtering, static synchroballistic, common voltage-type multi-level converter topology is broadly divided into case bit-type and the large class of unit cascaded type two at present.Module combination multi-level converter (Modular Multilevel Converter, MMC) as a kind of novel many level topology, except thering is traditional multi-level converter, module combination multi-level converter adopts Modular Structure Design, is convenient to System Expansion and redundancy of effort; Have unbalanced operation ability, fault traversing and recovery capability, system reliability is high; Owing to having common DC bus, module combination multi-level converter is particularly useful for HVDC (High Voltage Direct Current) transmission system application.But, in the time of the three-phase AC line of N bar different frequency connected, needing 2N MMC converter, this has increased engineering cost greatly.

Utility model content

The purpose of this utility model is to overcome above-mentioned the deficiencies in the prior art, proposes a kind of 3N+3 switches set MMC AC-AC converter.

The technical solution adopted in the utility model is: 3N+3 switches set MMC AC-AC converter comprises N three-phase alternating current I/O, the first brachium pontis, the second brachium pontis, the 3rd brachium pontis and the first electric capacity; Described three-phase alternating current I/O is three-phase alternating current input or three-phase alternating current output, and three-phase alternating current is output as three-phase inductive load; Described the first brachium pontis is in series by N+1 switches set and 2 inductance, and described the second brachium pontis is in series by N+1 switches set and 2 inductance, and described the 3rd brachium pontis is in series by N+1 switches set and 2 inductance; I switches set of the first brachium pontis is in series by n power switch unit, i switches set of the second brachium pontis is in series by n power switch unit, i switches set of the 3rd brachium pontis is in series by n power switch unit, and wherein the value of i is 1～N+1; N>2, n is positive integer.

Two inductance of the first brachium pontis intercouple, and form a pair of coupling inductance; Two inductance of the second brachium pontis intercouple, and form a pair of coupling inductance; Two inductance of the 3rd brachium pontis intercouple, and form a pair of coupling inductance.

In the time that k three-phase alternating current I/O is three-phase alternating current input, this three-phase alternating current input comprises u cross streams input power, v cross streams input power, w cross streams input power, u cross streams outputting inductance, v cross streams outputting inductance and w cross streams outputting inductance, one end of u cross streams input power and v cross streams input power, w cross streams input power connects, the other end of u cross streams input power is connected with one end of u cross streams outputting inductance, the other end of u cross streams input inductance is as the end of this three-phase alternating current input, the other end of v cross streams input power is connected with one end of v cross streams outputting inductance, the other end of v cross streams input inductance is as the end of this three-phase alternating current input, the other end of w cross streams input power is connected with one end of w cross streams outputting inductance, the other end of w cross streams input inductance is as the end of this three-phase alternating current input, wherein the value of k is 1～N, in the time that k three-phase alternating current I/O is three-phase inductive load, this three-phase inductive load comprises u phase resistance, v phase resistance, w phase resistance, u cross streams outputting inductance, v cross streams outputting inductance and w cross streams outputting inductance, one end of one end of u phase resistance and v phase resistance, one end of w phase resistance connects, the other end of u phase resistance is connected with one end of u cross streams outputting inductance, the other end of u cross streams outputting inductance is as the end of this three-phase inductive load, the other end of v phase resistance is connected with one end of v cross streams outputting inductance, the other end of v cross streams outputting inductance is as the end of this three-phase inductive load, the other end of w phase resistance is connected with one end of w cross streams outputting inductance, the other end of w cross streams outputting inductance is as the end of this three-phase inductive load.

The lower end of the 1st switches set of the first brachium pontis is connected with one end of the first inductance of 2 inductance in the first brachium pontis, and the other end of the first inductance of the first brachium pontis is connected with the upper end of the 2nd switches set of the first brachium pontis; The lower end of i switches set of the first brachium pontis is connected with the upper end of i+1 switches set of the first brachium pontis, and wherein the value of i is 2～N-1; The lower end of N switches set of the first brachium pontis is connected with one end of the second inductance of the first brachium pontis, and the other end of the second inductance of the first brachium pontis is connected with the upper end of N+1 switches set of the first brachium pontis; The circuit structure of the circuit structure of the second brachium pontis, the circuit structure of the 3rd brachium pontis and the first brachium pontis is in full accord; Three ends of k three-phase alternating current I/O are connected with the upper end of k+1 switches set of the upper end of k+1 switches set of the upper end of k+1 switches set of the first brachium pontis, the second brachium pontis, the 3rd brachium pontis respectively, and wherein the value of k is 1～N-1; Three ends of N three-phase alternating current I/O are connected with the lower end of N+1 switches set of the lower end of N+1 switches set of the first brachium pontis, the second brachium pontis, the lower end of N+1 switches set of the 3rd brachium pontis connects; The upper end of the upper end of the upper end of the 1st switches set of the first brachium pontis and the 1st switches set of the second brachium pontis, the 1st switches set of the 3rd brachium pontis, the positive pole of the first electric capacity are connected, the lower end of the lower end of the lower end of the negative pole of the first electric capacity and N+1 switches set of the first brachium pontis, N+1 switches set of the second brachium pontis, N+1 switches set of the 3rd brachium pontis, hold and be connected.

Power switch unit comprises the first switching tube, second switch pipe, the first diode, the second diode and the second electric capacity.Wherein, the positive pole of the second electric capacity is connected with the collector electrode of the first switching tube, the negative electrode of the first diode, the emitter of the first switching tube is connected with the anode of the first diode, the collector electrode of second switch pipe, the negative electrode of the second diode, and the emitter of second switch pipe is connected with the anode of the second diode, the negative pole of the second electric capacity; The collector electrode of second switch pipe is as the first output, and the emitter of second switch pipe is as the second output.

The second output of j power switch unit of i switches set of the first brachium pontis is connected with the first output of j+1 power switch unit of i switches set of the first brachium pontis, and wherein j value is 1～n-1, and i value is 1～N+1; The second output of j power switch unit of i switches set of the second brachium pontis is connected with the first output of j+1 power switch unit of i switches set of the second brachium pontis; The second output of j power switch unit of i switches set of the 3rd brachium pontis is connected with the first output of j+1 power switch unit of i switches set of the 3rd brachium pontis.

Adopt phase-shifting carrier wave PWM to control opening and turn-offing of each switching tube; J power switch unit of j power switch unit of j power switch unit of i switches set of the first brachium pontis, i switches set of the second brachium pontis and i switches set of the 3rd brachium pontis all adopts identical triangular wave as j carrier wave C _j, wherein the value of j is 1～n; N carrier wave 360 °/n of lagging phase angle successively; The end of the first brachium pontis of k three-phase alternating current I/O adopts k sinusoidal wave R of the first brachium pontis _sukk direct current biasing R superposes _dokobtain k modulating wave R of the first brachium pontis _suk+ R _dok, wherein the value of k is 1～N; The end of the second brachium pontis of k three-phase alternating current I/O adopts k sinusoidal wave R of the second brachium pontis _svkk direct current biasing R superposes _dokobtain k modulating wave R of the second brachium pontis _svk+ R _dok; The end of the 3rd brachium pontis of k three-phase alternating current I/O adopts k sinusoidal wave R of the 3rd brachium pontis _swkk direct current biasing R superposes _dokobtain k modulating wave R of the 3rd brachium pontis _swk+ R _dok; The k of a first brachium pontis sinusoidal wave R _suk, the second brachium pontis k sinusoidal wave R _svkk the sinusoidal wave R with the 3rd brachium pontis _swkphase place differs 120 ° successively.

K modulating wave R of the first brachium pontis _suk+ R _dokwith j carrier wave C _jby k comparator, as k modulating wave R of the first brachium pontis _suk+ R _dokbe greater than j carrier wave C _jtime, k comparator output high level, as k modulating wave R of the first brachium pontis _suk+ R _dokbe less than j carrier wave C _jtime, k comparator output low level, wherein the value of k is 1～N; The output of the 1st comparator is as the control level of the second switch pipe gate pole of j power switch unit of the 1st switches set of the first brachium pontis; The output of k-1 comparator is by k-1 not gate, the output of k-1 not gate and the output of k comparator obtain the control level of the second switch pipe gate pole of j power switch unit of k switches set of the first brachium pontis by k-1 XOR gate, wherein the value of k is 2～N; The output of N comparator obtains the control level of the second switch pipe gate pole of j power switch unit of N+1 switches set of the first brachium pontis by N not gate; K modulating wave R of the second brachium pontis _svk+ R _dokwith j carrier wave C _jby N+k comparator, as k modulating wave R of the second brachium pontis _svk+ R _dokbe greater than j carrier wave C _jtime, N+k comparator output high level, as k modulating wave R of the second brachium pontis _svk+ R _dokbe less than j carrier wave C _jtime, N+k comparator output low level, wherein the value of k is 1～N; The output of N+1 comparator is as the control level of the second switch pipe gate pole of j power switch unit of the 1st switches set of the second brachium pontis; The output of N+k-1 comparator is by N+k-1 not gate, the output of N+k-1 not gate and the output of N+k comparator obtain the control level of the second switch pipe gate pole of j power switch unit of k switches set of the second brachium pontis by N-1+k-1 XOR gate, wherein the value of k is 2～N; The output of 2*N comparator obtains the control level of the second switch pipe gate pole of j power switch unit of N+1 switches set of the second brachium pontis by 2*N not gate; K modulating wave R of the 3rd brachium pontis _swk+ R _dokwith j carrier wave C _jby 2*N+k comparator, as k modulating wave R of the 3rd brachium pontis _swk+ R _dokbe greater than j carrier wave C _jtime, 2*N+k comparator output high level, as k modulating wave R of the 3rd brachium pontis _swk+ R _dokbe less than j carrier wave C _jtime, 2*N+k comparator output low level, wherein the value of k is 1～N; The output of 2*N+1 comparator is as the control level of the second switch pipe gate pole of j power switch unit of the 1st switches set of the 3rd brachium pontis; The output of 2*N+k-1 comparator is by 2*N+k-1 not gate, the output of 2*N+k-1 not gate and the output of 2*N+k comparator obtain the control level of the second switch pipe gate pole of j power switch unit of k switches set of the 3rd brachium pontis by 2* (N-1)+k-1 XOR gate, wherein the value of k is 2～N; The output of 3*N comparator obtains the control level of the second switch pipe gate pole of j power switch unit of N+1 switches set of the 3rd brachium pontis by 3*N not gate.

The mode of operation of 3N+3 switches set MMC AC-AC converter comprises same mode of operation and alien frequencies mode of operation frequently, and in frequency mode of operation, the frequency that the input of N road three-phase alternating current or three-phase alternating current are exported is identical, and amplitude is not identical; In alien frequencies mode of operation, frequency and the amplitude of the input of N road three-phase alternating current or three-phase alternating current output are all different.

Compared with prior art, the advantage the utlity model has is: every road exchanges input and is all converted to the interchange input that line voltage is 2n+1 level, being transformed into line voltage through AC-AC is that load supplying is exported in the interchange of 2n+1 level, the voltage stress that in power switch unit, each switching tube bears is only the 1/n of DC bus-bar voltage, can ensure that the voltage that in the converter course of work, all switching tubes bear equates, has well solved the voltage-sharing of switching tube simultaneously.Compare with existing three-phase 3N+3 switch AC-AC converter, the N road three-phase alternating current input of 3N+3 switches set MMC AC-AC converter provided by the utility model or the line voltage of three-phase alternating current output are 2n+1 level, and the voltage stress bearing of each switching tube is only the 1/n of DC bus-bar voltage, well solved the voltage-sharing of switching tube, this will be very beneficial for the application of 3N+3 switches set MMC AC-AC converter in high pressure and large-power occasions.Compare with existing MMC converter, 3N+3 switches set MMC AC-AC converter provided by the utility model has the three-phase alternating current input of N road or three-phase alternating current output, can be directly used in N bar different frequency three-phase AC line be connected, greatly reduce engineering cost.

Brief description of the drawings

Fig. 1 is the circuit structure diagram of 3N+3 switches set MMC AC-AC converter of the present utility model;

Fig. 2 a, 2b are respectively the three-phase alternating current input of the 3N+3 switches set MMC AC-AC converter shown in Fig. 1 and the circuit structure diagram of three-phase inductive load;

Fig. 3 is the circuit structure diagram of the switch power unit of the 3N+3 switches set MMC AC-AC converter shown in Fig. 1;

Fig. 4 a, Fig. 4 b are two phase-shifting carrier wave PWM control structure figure of the 3N+3 switches set MMC AC-AC converter shown in Fig. 1;

Fig. 5 a, 5b are that twelvemo pass group MMC AC-AC converter works in respectively with the modulating wave under frequency mode of operation and alien frequencies mode of operation;

Fig. 6 a, 6b are that twelvemo pass is organized nine level MMC AC-AC converters and worked in the simulation waveform figure of mode of operation and alien frequencies mode of operation frequently.

Embodiment

For further setting forth content of the present utility model and feature, below in conjunction with accompanying drawing, embodiment of the present utility model is specifically described, but enforcement of the present utility model is not limited to this.

With reference to figure 1,3N+3 switches set MMC AC-AC converter of the present utility model, comprises N three-phase alternating current I/O, the first brachium pontis, the second brachium pontis, the 3rd brachium pontis and the first capacitor C ₁; Described the first brachium pontis is by N+1 switches set (B _u1, B _u2..., B _{u (N+1)}) and 2 inductance (L _u1, L _u2) be in series, described the second brachium pontis is by N+1 switches set (B _v1, B _v2..., B _{v (N+1)}) and 2 inductance (L _v1, L _v2) be in series, described the 3rd brachium pontis is by N+1 switches set (B _w1, B _w2..., B _{w (N+1)}) and 2 inductance (L _w1, L _w2) be in series; I switches set B of the first brachium pontis _uiby n power switch unit (SM _bui1, SM _bui2..., SM _buin) be in series, i switches set B of the second brachium pontis _viby n power switch unit (SM _bvi1, SM _bvi2..., SM _bvin) be in series, i switches set B of the 3rd brachium pontis _wiby n power switch unit (SM _bwi1, SM _bwi2..., SM _bwin) be in series, wherein the value of i is 1～N+1; Three ends of each three-phase inductive load are exported as each three-phase alternating current; N>2, n is positive integer.

The 1st switches set B of the first brachium pontis _u1lower end p and the first brachium pontis in the first inductance L of 2 inductance _u1one end connect, the first inductance L of the first brachium pontis _u1the other end and the 2nd switches set B of the first brachium pontis _u2upper end o connect; I switches set B of the first brachium pontis _uilower end and i+1 switches set (B of the first brachium pontis _{u (i+1)}) upper end connect, wherein the value of i is 2～N-1; N switches set B of the first brachium pontis _uNlower end and the second inductance L of the first brachium pontis _u2one end connect, the second inductance L of the first brachium pontis _u2the other end and N+1 switches set B of the first brachium pontis _{u (N+1)}upper end connect; The circuit structure of the circuit structure of the second brachium pontis, the circuit structure of the 3rd brachium pontis and the first brachium pontis is in full accord; Three ends of k three-phase alternating current I/O respectively with k+1 switches set B of the first brachium pontis _{u (k+1)}upper end, k+1 switches set B of the second brachium pontis _{v (k+1)}upper end, k+1 switches set B of the 3rd brachium pontis _{w (k+1)}upper end connect, wherein the value of k is 1～N-1; Three ends of N three-phase alternating current I/O and N+1 switches set B of the first brachium pontis _{u (N+1)}lower end, N+1 switches set B of the second brachium pontis _{v (N+1)}lower end connect, N+1 switches set B of the 3rd brachium pontis _{w (N+1)}lower end connect; The 1st switches set B of the first brachium pontis _u1upper end and the 1st switches set B of the second brachium pontis _v1upper end, the 1st switches set B of the 3rd brachium pontis _w1upper end, the first capacitor C ₁positive pole connect, the first capacitor C ₁negative pole and N+1 switches set B of the first brachium pontis _{u (N+1)}lower end, N+1 switches set B of the second brachium pontis _{v (N+1)}lower end, N+1 switches set B of the 3rd brachium pontis _{w (N+1)}lower end, hold G connect.

In the time that k three-phase alternating current I/O is three-phase alternating current input, this three-phase alternating current input comprises u cross streams input power u _uk, v cross streams input power u _vk, w cross streams input power u _wk, u cross streams outputting inductance L _iuk, v cross streams outputting inductance L _ivkwith w cross streams outputting inductance L _iwk, u cross streams input power u _ukone end and v cross streams input power u _vk, w cross streams input power u _wkconnect u cross streams input power u _ukthe other end and u cross streams outputting inductance L _iukone end connect, u cross streams input inductance L _iukthe other end as the end a of this three-phase alternating current input _uk, v cross streams input power v _vkthe other end and v cross streams outputting inductance L _ivkone end connect, v cross streams input inductance L _ivkthe other end as the end a of this three-phase alternating current input _vk, w cross streams input power w _wkthe other end and w cross streams outputting inductance L _iwkone end connect, w cross streams input inductance L _iwkthe other end as the end a of this three-phase alternating current input _wk, as shown in Figure 2 a, wherein the value of k is 1～N; In the time that k three-phase alternating current I/O is three-phase inductive load, this three-phase inductive load comprises u phase resistance R _uk, v phase resistance R _vk, w phase resistance R _wk, u cross streams outputting inductance L _ouk, v cross streams outputting inductance L _ovkwith w cross streams outputting inductance L _owk, u phase resistance R _ukone end and v phase resistance R _vkone end, w phase resistance R _wkone end connect, u phase resistance R _ukthe other end and u cross streams outputting inductance L _oukone end connect, u cross streams outputting inductance L _oukthe other end as the end a of this three-phase inductive load _uk, v phase resistance R _vkthe other end and v cross streams outputting inductance L _ovkone end connect, v cross streams outputting inductance L _ovkthe other end as the end a of this three-phase inductive load _vk, w phase resistance R _wkthe other end and w cross streams outputting inductance L _owkone end connect, w cross streams outputting inductance L _owkthe other end as the end a of this three-phase inductive load _wk, as shown in Figure 2 b.

Fig. 3 illustrates the circuit structure diagram of the switch power unit of the 3N+3 switches set MMC AC-AC converter shown in Fig. 1.Power switch unit comprises the first switching tube S ₁, second switch pipe S ₂, the first diode D ₁, the second diode D ₂and capacitor C _sM.Wherein, capacitor C _sMpositive pole and the first switching tube S ₁collector electrode, the first diode D ₁negative electrode connect, the first switching tube S ₁emitter and the first diode D ₁anode, second switch pipe S ₂collector electrode, the second diode D ₂negative electrode connect, second switch pipe S ₂emitter and the second diode D ₂anode, capacitor C _sMnegative pole connect; Second switch pipe S ₂collector electrode as the first output, second switch pipe S ₂emitter as the second output.

As shown in Figure 1, i switches set B of the first brachium pontis _uij power switch unit SM _buijthe second output and i switches set B of the first brachium pontis _uij+1 power switch unit SM _{bui (j+1)}first output connect, wherein j value is 1～n-1, i value is 1～N+1; I switches set B of the second brachium pontis _vij power switch unit SM _bvijthe second output and i switches set B of the second brachium pontis _vij+1 power switch unit SM _{bvi (j+1)}first output connect; I switches set B of the 3rd brachium pontis _vij power switch unit SM _bvijthe second output and i switches set B of the 3rd brachium pontis _vij+1 power switch unit SM _{bvi (j+1)}first output connect.

Make the u phase voltage source of k three-phase alternating current input or three-phase alternating current output be the v phase voltage source of the input of k three-phase alternating current or three-phase alternating current output is the w phase voltage source of the input of k three-phase alternating current or three-phase alternating current output is :

In formula, U _c1it is the first capacitor C ₁voltage.

3N+3 switches set MMC AC-AC converter using phase-shifting carrier wave PWM shown in Fig. 1 controls, as shown in Fig. 4 a～Fig. 4 b.

Adopt phase-shifting carrier wave PWM to control each switches set B of the first brachium pontis _ui, the second brachium pontis each switches set B _vieach switches set B with the 3rd brachium pontis _withe opening and turn-offing of each switching tube, wherein i value is 1～N+1; I switches set B of the first brachium pontis _uij power switch unit SM _buij, the second brachium pontis i switches set B _vij power switch unit SM _bviji the switches set B with the 3rd brachium pontis _wij power switch unit SM _bwijall adopt identical triangular wave as j carrier wave C _j, wherein the value of j is 1～n; N carrier wave (C ₁, C ₂..., C _n) 360 °/n of lagging phase angle successively; The end a of the first brachium pontis of k three-phase alternating current I/O _ukadopt k sinusoidal wave R of the first brachium pontis _sukk direct current biasing R superposes _dokobtain k modulating wave R of the first brachium pontis _suk+ R _dok, wherein the value of k is 1～N; The end a of the second brachium pontis of k three-phase alternating current I/O _vkadopt k sinusoidal wave R of the second brachium pontis _svkk direct current biasing R superposes _dokobtain k modulating wave R of the second brachium pontis _svk+ R _dok; The end a of the 3rd brachium pontis of k three-phase alternating current I/O _wkadopt k sinusoidal wave R of the 3rd brachium pontis _swkk direct current biasing R superposes _dokobtain k modulating wave R of the 3rd brachium pontis _swk+ R _dok; The k of a first brachium pontis sinusoidal wave R _suk, the second brachium pontis k sinusoidal wave R _svkk the sinusoidal wave R with the 3rd brachium pontis _swkphase place differs 120 ° successively.

K modulating wave R of the first brachium pontis _suk+ R _dokwith j carrier wave C _jby k comparator, as k modulating wave R of the first brachium pontis _suk+ R _dokbe greater than j carrier wave C _jtime, k comparator output high level, as k modulating wave R of the first brachium pontis _suk+ R _dokbe less than j carrier wave C _jtime, k comparator output low level, wherein the value of k is 1～N; The output of the 1st comparator is as the 1st switches set B of the first brachium pontis _u1j power switch unit SM _bu1jsecond switch pipe S ₂the control level S of gate pole _bu1j; The output of k-1 comparator is by k-1 not gate, and the output of k-1 not gate and the output of k comparator obtain k switches set B of the first brachium pontis by k-1 XOR gate _ukj power switch unit SM _bukjsecond switch pipe S ₂the control level S of gate pole _bukj, wherein the value of k is 2～N; The output of N comparator obtains N+1 switches set B of the first brachium pontis by N not gate _{u (N+1)}j power switch unit SM _{bu (N+1) j}second switch pipe S ₂the control level S of gate pole _{bu (N+1) j}; K modulating wave R of the second brachium pontis _svk+ R _dokwith j carrier wave C _jby N+k comparator, as k modulating wave R of the second brachium pontis _svk+ R _dokbe greater than j carrier wave C _jtime, N+k comparator output high level, as k modulating wave R of the second brachium pontis _svk+ R _dokbe less than j carrier wave C _jtime, N+k comparator output low level, wherein the value of k is 1～N; The output of N+1 comparator is as the 1st switches set B of the second brachium pontis _v1j power switch unit SM _bv1jsecond switch pipe S ₂the control level S of gate pole _bv1j; The output of N+k-1 comparator is by N+k-1 not gate, and the output of N+k-1 not gate and the output of N+k comparator obtain k switches set B of the second brachium pontis by N-1+k-1 XOR gate _vkj power switch unit SM _bvkjthe control level S of second switch pipe S2 gate pole _bvkj, wherein the value of k is 2～N; The output of 2*N comparator obtains N+1 switches set B of the second brachium pontis by 2*N not gate _{v (N+1)}j power switch unit SM _{bv (N+1) j}second switch pipe S ₂the control level S of gate pole _{bv (N+1) j}; K modulating wave R of the 3rd brachium pontis _swk+ R _dokwith j carrier wave C _jby 2*N+k comparator, as k modulating wave R of the 3rd brachium pontis _swk+ R _dokbe greater than j carrier wave C _jtime, 2*N+k comparator output high level, as k modulating wave R of the 3rd brachium pontis _swk+ R _dokbe less than j carrier wave C _jtime, 2*N+k comparator output low level, wherein the value of k is 1～N; The output of 2*N+1 comparator is as the 1st switches set B of the 3rd brachium pontis _w1j power switch unit SM _bw1jsecond switch pipe S ₂the control level S of gate pole _bw1j; The output of 2*N+k-1 comparator is by 2*N+k-1 not gate, and the output of 2*N+k-1 not gate and the output of 2*N+k comparator obtain k switches set B of the 3rd brachium pontis by 2* (N-1)+k-1 XOR gate _wkj power switch unit SM _bwkjsecond switch pipe S ₂the control level S of gate pole _bwkj, wherein the value of k is 2～N; The output of 3*N comparator obtains N+1 switches set B of the 3rd brachium pontis by 3*N not gate _{w (N+1)}j power switch unit SM _{bw (N+1) j}second switch pipe S ₂the control level S of gate pole _{bw (N+1) j}.Second switch pipe (S in each power switch unit of each switches set ₂) obtain the first switching tube (S in this power switch unit after the control level of gate pole is anti-phase ₁) control level of gate pole.

Each brachium pontis that described control method can ensure described converter each time be carved with the output voltage u of n power switch unit _sM=E, the output voltage u of N*n power switch unit _sM=0, meet ${\mathrm{\Σ}}_{i=1}^{N+1}{u}_{\mathrm{Bui}}=U_{C1},{\mathrm{\Σ}}_{i=1}^{N+1}{u}_{\mathrm{Bvi}}=U_{C1}$ With ${\mathrm{\Σ}}_{i=1}^{N+1}{u}_{\mathrm{Bwi}}=U_{C1},$ Wherein u _buibe the output voltage of i switches set of the first brachium pontis, u _bvibe the output voltage of i switches set of the second brachium pontis, u _bwibe the output voltage of i switches set of the 3rd brachium pontis, E is the second capacitor C in each power switch unit _sMon voltage, and have E=U _c1/ n, the voltage stress that in power switch unit, each switching tube bears is only the 1/n of DC bus-bar voltage, can ensure that the voltage that in the converter course of work, all switching tubes bear equates, has well solved the voltage-sharing of switching tube simultaneously.

Taking twelvemo pass group MMC AC-AC converter (N=3) as example, comprise two three-phase alternating current inputs and a three-phase alternating current output, Fig. 5 a illustrates that it works in the 1st the modulating wave R with the first brachium pontis under frequency mode of operation _su1+ R _do1, the first brachium pontis the 2nd modulating wave R _su2+ R _do2, the first brachium pontis the 3rd modulating wave R _su3+ R _do3with j carrier wave C _jrelation.Can find out the 1st sinusoidal wave R of the first brachium pontis from Fig. 5 a _su1, the first brachium pontis the 2nd sinusoidal wave R _su2the 3rd the sinusoidal wave R with the first brachium pontis _su3frequency identical, amplitude is not identical.Fig. 5 b illustrates that it works in the 1st modulating wave R of the first brachium pontis under alien frequencies mode of operation _su1+ R _do1, the first brachium pontis the 2nd modulating wave R _su2+ R _do2, the first brachium pontis the 3rd modulating wave R _su3+ R _do3with j carrier wave C _jrelation.Can find out the 1st sinusoidal wave R of the first brachium pontis from Fig. 5 b _su1, the first brachium pontis the 2nd sinusoidal wave R _su2the 3rd the sinusoidal wave R with the first brachium pontis _su3frequency and amplitude all not identical.The 1st modulating wave R of the second brachium pontis _sv1+ R _do1, the second brachium pontis the 2nd modulating wave R _sv2+ R _do2, the second brachium pontis the 3rd modulating wave R _sv3+ R _do3with j carrier wave C _jrelation and the 1st modulating wave R of the first brachium pontis _su1+ R _do1, the first brachium pontis the 2nd modulating wave R _su2+ R _do2, the first brachium pontis the 3rd modulating wave R _su3+ R _do3with j carrier wave C _jrelation identical; The 1st modulating wave R of the 3rd brachium pontis _sw1+ R _do1, the 3rd brachium pontis the 2nd modulating wave R _sw2+ R _do2, the 3rd brachium pontis the 3rd modulating wave R _sw3+ R _do3with j carrier wave C _jrelation and the first brachium pontis the 1st modulating wave R _su1+ R _do1, the first brachium pontis the 2nd modulating wave R _su2+ R _do2, the first brachium pontis the 3rd modulating wave R _su3+ R _do3with j carrier wave C _jrelation identical.

Organize nine level MMC AC-AC converters (N=3, n=4) taking twelvemo pass as example, comprise two three-phase alternating current inputs and a three-phase alternating current output.Fig. 6 a is that it works in the simulation waveform figure with frequency mode of operation, is 3 phase voltage (u of the 1st three-phase alternating current input successively _su1, u _sv1, u _sw1), 3 line voltage (u after the 1st three-phase alternating current input conversion _suv1, u _svw1, u _swu1), 3 phase voltage (u of the 2nd three-phase alternating current input _su2, u _sv2, u _sw2), 3 line voltage (u after the 2nd three-phase alternating current input conversion _suv2, u _svw2, u _swu2), 3 line voltage (u of three-phase alternating current output _luv3, u _lvw3, u _lwu3), 3 line current (i of three-phase alternating current output _lu3, i _lv3, i _lw3), identical with the frequency of three-phase alternating current output from visible the 1st three-phase alternating current input of Fig. 6 a, the 2nd three-phase alternating current input, amplitude is not identical; Fig. 6 b is its simulation waveform figure that works in alien frequencies mode of operation, is 3 phase voltage (u of the 1st three-phase alternating current input successively _su1, u _sv1, u _sw1), 3 line voltage (u after the 1st three-phase alternating current input conversion _suv1, u _svw1, u _swu1), 3 phase voltage (u of the 2nd three-phase alternating current input _su2, u _sv2, u _sw2), 3 line voltage (u after the 2nd three-phase alternating current input conversion _suv2, u _svw2, u _swu2), 3 line voltage (u of three-phase alternating current output _luv3, u _lvw3, u _lwu3), 3 line current (i of three-phase alternating current output _lu3, i _lv3, i _lw3), input all not identical with frequency and the amplitude of three-phase alternating current output from visible the 1st the three-phase alternating current input of Fig. 6 a, the 2nd three-phase alternating current.

Above-described embodiment is preferably execution mode of the utility model; but execution mode of the present utility model is not limited by the examples; other any do not deviate from change, the modification done under Spirit Essence of the present utility model and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection range of the present utility model.

Claims (6)

1.3N+3 switches set MMC AC-AC converter, is characterized in that: comprise N three-phase alternating current I/O, the first brachium pontis, the second brachium pontis, the 3rd brachium pontis and the first electric capacity ( c ₁); Described three-phase alternating current I/O is three-phase alternating current input or three-phase alternating current output, and three-phase alternating current is output as three-phase inductive load; Described the first brachium pontis is by N+1 switches set (B _u1, B _u2..., B _{u (N+1)}) and 2 inductance ( l _u1 , l _u2 ) be in series, described the second brachium pontis is by N+1 switches set (B _v1, B _v2..., B _{v (N+1)}) and 2 inductance ( l _v1 , l _v2 ) be in series, described the 3rd brachium pontis is by N+1 switches set (B _w1, B _w2..., B _{w (N+1)}) and 2 inductance ( l _w1 , l _w2 ) be in series; I switches set (B of the first brachium pontis _ui) by n power switch unit (SM _bui1, SM _bui2..., SM _buin) be in series, i switches set (B of the second brachium pontis _vi) by n power switch unit (SM _bvi1, SM _bvi2..., SM _bvin) be in series, i switches set (B of the 3rd brachium pontis _wi) by n power switch unit (SM _bwi1, SM _bwi2..., SM _bwin) be in series, wherein the value of i is 1 ~ N+1; N>2, n is positive integer.

2. 3N+3 switches set MMC AC-AC converter according to claim 1, is characterized in that: two inductance of the first brachium pontis ( l _u1 , l _u2 ) intercouple, form a pair of coupling inductance; Two inductance of the second brachium pontis ( l _v1 , l _v2 ) intercouple, form a pair of coupling inductance; Two inductance of the 3rd brachium pontis ( l _w1 , l _w2 ) intercouple, form a pair of coupling inductance.

3. 3N+3 switches set MMC AC-AC converter according to claim 1, is characterized in that: the 1st switches set (B of the first brachium pontis _u1) lower end (p) and the first brachium pontis in 2 inductance the first inductance ( l _u1 ) one end connect, the first inductance of the first brachium pontis ( l _u1 ) the other end and the 2nd switches set (B of the first brachium pontis _u2) upper end (o) connect; I switches set (B of the first brachium pontis _ui) lower end and i+1 switches set (B of the first brachium pontis _{u (i+1)}) upper end connect, wherein the value of i is 2 ~ N-1; N switches set (B of the first brachium pontis _uN) lower end and the second inductance of the first brachium pontis ( l _u2 ) one end connect, the second inductance of the first brachium pontis ( l _u2 ) the other end and N+1 switches set (B of the first brachium pontis _{u (N+1)}) upper end connect; The circuit structure of the circuit structure of the second brachium pontis, the circuit structure of the 3rd brachium pontis and the first brachium pontis is in full accord; Three ends of k three-phase alternating current I/O respectively with k+1 switches set (B of the first brachium pontis _{u (k+1)}) upper end, k+1 switches set (B of the second brachium pontis _{v (k+1)}) upper end, k+1 switches set (B of the 3rd brachium pontis _{w (k+1)}) upper end connect, wherein the value of k is 1 ~ N-1; Three ends of N three-phase alternating current I/O and N+1 switches set (B of the first brachium pontis _{u (N+1)}) lower end, N+1 switches set (B of the second brachium pontis _{v (N+1)}) lower end connect, N+1 switches set (B of the 3rd brachium pontis _{w (N+1)}) lower end connect; The 1st switches set (B of the first brachium pontis _u1) upper end and the 1st switches set (B of the second brachium pontis _v1) upper end, the 1st switches set (B of the 3rd brachium pontis _w1) upper end, the first electric capacity ( c ₁) positive pole connect, the first electric capacity ( c ₁) negative pole and N+1 switches set (B of the first brachium pontis _{u (N+1)}) lower end, N+1 switches set (B of the second brachium pontis _{v (N+1)}) lower end, N+1 switches set (B of the 3rd brachium pontis _{w (N+1)}) lower end, hold ( g) connect.

4. 3N+3 switches set MMC AC-AC converter according to claim 1, is characterized in that: when k three-phase alternating current I/O is three-phase alternating current when input, this three-phase alternating current input comprise u cross streams input power ( u _uk ), v cross streams input power ( u _vk ), w cross streams input power ( u _wk ), u cross streams outputting inductance ( l _iuk ), v cross streams outputting inductance ( l _ivk ) and w cross streams outputting inductance ( l _iwk ), u cross streams input power ( u _uk ) one end and v cross streams input power ( u _vk ), w cross streams input power ( u _wk ) connect, u cross streams input power ( u _uk ) the other end and u cross streams outputting inductance ( l _iuk ) one end connect, u cross streams input inductance ( l _iuk ) the other end as the end of this three-phase alternating current input ( a _uk ), v cross streams input power ( v _vk ) the other end and v cross streams outputting inductance ( l _ivk ) one end connect, v cross streams input inductance ( l _ivk ) the other end as the end of this three-phase alternating current input ( a _vk ), w cross streams input power ( w _wk ) the other end and w cross streams outputting inductance ( l _iwk ) one end connect, w cross streams input inductance ( l _iwk ) the other end as the end of this three-phase alternating current input ( a _wk ), wherein the value of k is 1 ~ N; In the time that k three-phase alternating current I/O is three-phase inductive load, this three-phase inductive load comprise u phase resistance ( r _uk ), v phase resistance ( r _vk ), w phase resistance ( r _wk ), u cross streams outputting inductance ( l _ouk ), v cross streams outputting inductance ( l _ovk ) and w cross streams outputting inductance ( l _owk ), u phase resistance ( r _uk ) one end and v phase resistance ( r _vk ) one end, w phase resistance ( r _wk ) one end connect, u phase resistance ( r _uk ) the other end and u cross streams outputting inductance ( l _ouk ) one end connect, u cross streams outputting inductance ( l _ouk ) the other end as the end of this three-phase inductive load ( a _uk ), v phase resistance ( r _vk ) the other end and v cross streams outputting inductance ( l _ovk ) one end connect, v cross streams outputting inductance ( l _ovk ) the other end as the end of this three-phase inductive load ( a _vk ), w phase resistance ( r _wk ) the other end and w cross streams outputting inductance ( l _owk ) one end connect, w cross streams outputting inductance ( l _owk ) the other end as the end of this three-phase inductive load ( a _wk ).

5. 3N+3 switches set MMC AC-AC converter according to claim 1, is characterized in that: power switch unit comprise the first switching tube ( s ₁), second switch pipe ( s ₂), the first diode ( d ₁), the second diode ( d ₂) and the second electric capacity ( c _sM ), wherein, the second electric capacity (C _sM) positive pole and the first switching tube ( s ₁) collector electrode, the first diode ( d ₁) negative electrode connect, the first switching tube ( s ₁) emitter and the first diode ( d ₁) anode, second switch pipe ( s ₂) collector electrode, the second diode ( d ₂) negative electrode connect, second switch pipe ( s ₂) emitter and the second diode ( d ₂) anode, the second electric capacity ( c _sM ) negative pole connect; Second switch pipe ( s ₂) collector electrode as the first output, second switch pipe ( s ₂) emitter as the second output.

6. 3N+3 switches set MMC AC-AC converter according to claim 1, is characterized in that: i switches set (B of the first brachium pontis _ui) j power switch unit (SM _buij) the second output and i switches set (B of the first brachium pontis _ui) j+1 power switch unit (SM _{bui (j+1)}) first output connect, wherein j value is 1 ~ n-1, i value is 1 ~ N+1; I switches set (B of the second brachium pontis _vi) j power switch unit (SM _bvij) the second output and i switches set (B of the second brachium pontis _vi) j+1 power switch unit (SM _{bvi (j+1)}) first output connect; I switches set (B of the 3rd brachium pontis _vi) j power switch unit (SM _bvij) the second output and i switches set (B of the 3rd brachium pontis _vi) j+1 power switch unit (SM _{bvi (j+1)}) first output connect.