CN203691277U - N-output single-phase 2N+2 switching group MMC (Modular Multilevel Converter) inverter - Google Patents

Abstract

The utility model provides an N-output single-phase 2N+2 switching group MMC (Modular Multilevel Converter) inverter. The inverter comprises a direct current power supply, a first bridge arm, a second bridge arm and N loads. The two bridge arms are formed by connecting N+1 switching groups and two inductors in series respectively. Each switching group of each bridge arm is formed by connecting n power switch units in series. Two ends of a kth load are respectively connected with upper ends of k+1th switching groups of the two bridge arms, wherein the value of k is from 1 to N-1. Two ends of an Nth load are connected with lower ends of Nth switching group of the two bridge arms respectively. The inverter adopts carrier phase-shifted PWM control and has N paths of alternating current output of 2n+1 level. Voltage stress applied to each switch tube of one MMC power switch unit is 1/n of voltage of the direct current power supply. A problem of voltage equalization of switch tubes is well solved. The inverter is suitable for being applied to high-voltage and large-power occasions. The two inductors of each bridge arm can be mutually coupled to form a pair of coupling inductors.

Description

N output single-phase 2N+2 switches set MMC inverter

Technical field

The module that relates to the utility model combines many level (MMC) converter field, is specifically related to a kind of N output single-phase 2N+2 switches set MMC inverter.

Background technology

, under this trend, there is the direction of two kinds of improvement converters: reduce passive device or improve converter topology structure to reduce active device as the new development that reduces active device direction at present power inverter forward miniaturization, high reliability and low-loss future development.Single-phase 2N+2 switch converters has reduced 2N-2 switch and corresponding drive circuit with respect to traditional 4N switch converters, in the application of considering cost and volume, occupies certain advantage.But the single-phase output in N road of 2N+2 switch converters is two level, output AC waveform is poor.In addition, the half that the voltage stress that in 2N+2 switch, each switch bears is DC bus-bar voltage, and there is the voltage-sharing of 2N+2 switching tube, this has limited the application of single-phase 2N+2 switch converters 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 having advantages of 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 alternating current circuit 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 N output single-phase 2N+2 switches set MMC inverter without direct current biasing.

The technical solution adopted in the utility model is as follows:

N output single-phase 2N+2 switches set MMC inverter comprises DC power supply, the first brachium pontis, the second brachium pontis and N 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; I switches set of the first brachium pontis is in series by n power switch unit, and i switches set of the second brachium pontis is in series by n power switch unit, and wherein the value of i is 1～N+1; The two ends of k load are connected with the upper end of k+1 switches set of the first brachium pontis and the upper end of k+1 switches set of the second brachium pontis respectively, and wherein the value of k is 1～N-1; The lower end of N switches set of the first brachium pontis and the lower end of N switches set of the second brachium pontis are received respectively in the two ends of N load; The two ends of k load are as the output of k road, and wherein the value of k is 1～N.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.N>2, n is positive integer.

In described N output single-phase 2N+2 switches set MMC inverter, the upper end of the upper end of the positive pole of DC power supply and the 1st switches set of the first brachium pontis, the 1st switches set of the second brachium pontis is connected; The lower end of the 1st switches set of the first brachium pontis is connected with one end of the 1st inductance of the first brachium pontis, and the other end of the 1st 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 2nd inductance of the first brachium pontis, and the other end of the 2nd 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 and the first brachium pontis is in full accord; The two ends of k load are connected with the upper end of k+1 switches set of the first brachium pontis and the upper end of k+1 switches set of the second brachium pontis respectively, and wherein the value of k is 1～N-1; The lower end of N switches set of the first brachium pontis is received respectively at the two ends of N load.

Described power switch unit is made up of the first switching tube, second switch pipe, the first diode, the second diode and electric capacity.Wherein, the positive pole of 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 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 described 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 first brachium pontis.

In above-mentioned inverter, adopt phase-shifting carrier wave PWM to control the opening and turn-offing of each switching tube of each switches set of the first brachium pontis and each switches set of the second brachium pontis, wherein i value is 1～N+1; J power switch unit of j power switch unit of i switches set of the first brachium pontis and i switches set of the second 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 load adopts k sinusoidal wave R of the first brachium pontis _lakk direct current biasing R superposes _dokobtain k modulating wave R of the first brachium pontis _lak+ R _dok, wherein the value of k is 1～N; The end of the second brachium pontis of k load adopts k sinusoidal wave R of the second brachium pontis _lbkk direct current biasing R superposes _dokobtain k modulating wave R of the second brachium pontis _lbk+ R _dok; The k of a first brachium pontis sinusoidal wave R _lakk the sinusoidal wave R with the second brachium pontis _lbkphase phasic difference 180 ^°.

K modulating wave R of the first brachium pontis _lak+ R _dokwith j carrier wave C _jby k comparator, as k modulating wave R of the first brachium pontis _lak+ R _dokbe greater than j carrier wave C _jtime, k comparator output high level, as k modulating wave R of the first brachium pontis _lak+ 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 _lbk+ R _dokwith j carrier wave C _jby N+k comparator, as k modulating wave R of the second brachium pontis _lbk+ 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 _lbk+ 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.

The mode of operation of described N output single-phase 2N+2 switches set MMC inverter comprises that, with frequency mode of operation (CF pattern) and alien frequencies mode of operation (DF pattern), in CF pattern, the frequency of N road output is identical, and amplitude is not identical; In DF pattern, the frequency of N road output and amplitude are all different.

Compared with prior art, the advantage the utlity model has is: have N road 2n+1 level and exchange output, output current wave is of high quality, the voltage stress that in power switch unit, each switching tube bears is only the 1/n of DC bus-bar voltage, can guarantee 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 single-phase 2N+2 switch converters, the N road output of N output single-phase 2N+2 switches set MMC inverter provided by the utility model is 2n+1 level and exchanges output, and the quality of output AC waveform is greatly improved.In addition, the voltage stress bearing of each switching tube is only the 1/n of DC bus-bar voltage, and control method provided by the utility model equates the voltage that in the converter course of work, all switching tubes bear, well solved the voltage-sharing of switching tube, this will be very beneficial for the application of N output single-phase 2N+2 switches set MMC inverter in high pressure and large-power occasions.Compare with existing MMC converter, N output single-phase 2N+2 switches set MMC inverter provided by the utility model have N road exchange output, can be directly used in N bar different frequency alternating current circuit be connected, greatly reduce engineering cost.

Accompanying drawing explanation

Fig. 1 is the circuit structure diagram of N output single-phase 2N+2 switches set MMC inverter of the present utility model;

Fig. 2 is the circuit structure diagram of the power switch unit of the N output single-phase 2N+2 switches set MMC inverter shown in Fig. 1;

Fig. 3 is the phase-shifting carrier wave PWM control structure figure of the N output single-phase 2N+2 switches set MMC inverter shown in Fig. 1;

Fig. 4 a, 4b are that three output single-phase eight switches set nine level MMC inverters work in respectively the modulating wave under CF pattern and DF pattern;

Fig. 5 a, 5b are the simulation waveform figure that three output single-phase eight switches set nine level MMC inverters work in CF pattern and DF pattern.

Embodiment

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

With reference to figure 1, N output single-phase 2N+2 switches set MMC inverter of the present utility model, comprises DC power supply U _dc, the first brachium pontis, the second brachium pontis and N load; Described the first brachium pontis is by N+1 switches set (B ₀₁, B ₀₂..., B _{0 (N+1)}) and 2 inductance (L ₀₁, L ₀₂) be in series, described the second brachium pontis is by N+1 switches set (B ₁₁, B ₁₂..., B _{1 (N+1)}) and 2 inductance (L ₀₁, L ₀₂) be in series; I switches set B of the first brachium pontis _0iby n power switch unit (SM _b0i1, SM _b0i2..., SM _b0in) be in series, i switches set B of the second brachium pontis _1iby n power switch unit SM _b1i1, SM _b1i2..., SM _b1inbe in series, wherein the value of i is 1～N+1; The two ends of k load respectively with k+1 switches set B of the first brachium pontis _{0 (k+1)}upper end o and k+1 switches set B of the second brachium pontis _{1 (k+1)}upper end o connect, wherein the value of k is 1～N-1; N switches set B of the first brachium pontis received respectively at the two ends of N load _0Nlower end p and N switches set B of the second brachium pontis _1Nlower end p; The two ends of k load are as the output of k road, and wherein the value of k is 1～N, N>2, and n is positive integer.

DC power supply U _dcthe upper end o of the 1st switches set of upper end o, the second brachium pontis of positive pole and the 1st switches set of the first brachium pontis be connected; The 1st switches set B of the first brachium pontis ₀₁lower end p and the 1st inductance L of the first brachium pontis ₀₁one end connect, the 1st inductance L of the first brachium pontis ₀₁the other end and the 2nd switches set B of the first brachium pontis ₀₂upper end o connect; I switches set B of the first brachium pontis _0ilower end p and i+1 switches set B of the first brachium pontis _{0 (i+1)}upper end o connect, wherein the value of i is 2～N-1; N switches set B of the first brachium pontis _0Nlower end p and the 2nd inductance L of the first brachium pontis ₀₂one end connect, the 2nd inductance L of the first brachium pontis ₀₂the other end and N+1 switches set B of the first brachium pontis _{0 (N+1)}upper end o connect; The circuit structure of the circuit structure of the second brachium pontis and the first brachium pontis is in full accord; The two ends of k load respectively with k+1 switches set B of the first brachium pontis _{0 (k+1)}upper end o and k+1 switches set B of the second brachium pontis _{1 (k+1)}upper end o connect, wherein the value of k is 1～N-1; N switches set B of the first brachium pontis received respectively at the two ends of N load _0Nlower end p.

Fig. 2 illustrates the circuit structure diagram of the power switch unit of the N output single-phase 2N+2 switches set MMC inverter shown in Fig. 1, and power switch unit is by the first switching tube S ₁, second switch pipe S ₂, the first diode D ₁, the second diode D ₂and capacitor C _sMform.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 _0ij power switch unit SM _b0ijthe second output and i switches set B of the first brachium pontis _0ij+1 power switch unit SM _{b0i (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 _1ij power switch unit SM _b1ijthe second output and i switches set B of the first brachium pontis _1ij+1 power switch unit SM _{b1i (j+1)}first output connect.

As shown in Figure 1, the voltage of k road output is:

$u_{\mathrm{Lk}}=\frac{\underset{i=N+1-K}{\overset{N+1}{\mathrm{\Σ}}}{u}_{B0i}-\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{u}_{B0i}}{2}-\frac{\underset{i=N+1-K}{\overset{N+1}{\mathrm{\Σ}}}{u}_{B1i}-\underset{i=1}{\overset{k}{\mathrm{\Σ}}}{u}_{B1i}}{2}(k=\mathrm{1,2},\·\·\·,N)---\left(1\right)$

In formula (1), u _b0ibe the output voltage of i switches set of the first brachium pontis, u _b1iit is the output voltage of i switches set of the second brachium pontis.

N output single-phase 2N+2 switches set MMC inverter shown in Fig. 1 adopts phase-shifting carrier wave PWM to control, as shown in Figure 3, and i switches set B of the first brachium pontis _0ij power switch unit SM _b0iji the switches set B with the second brachium pontis _1ij power switch unit SM _b1ijall 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 _n360 °/n of lagging phase angle successively; The end a of the first brachium pontis of k load _kadopt k sinusoidal wave R of the first brachium pontis _lakk direct current biasing R superposes _dokobtain k modulating wave R of the first brachium pontis _lak+ R _dok, wherein the value of k is 1～N; The end b of the second brachium pontis of k load _kadopt k sinusoidal wave R of the second brachium pontis _lbkk direct current biasing R superposes _dokobtain k modulating wave R of the second brachium pontis _lbk+ R _dok; The k of a first brachium pontis sinusoidal wave R _lakk the sinusoidal wave R with the second brachium pontis _lbk180 ° of phase phasic differences.

K modulating wave R of the first brachium pontis _lak+ R _dokwith j carrier wave C _jby k comparator, as k modulating wave R of the first brachium pontis _lak+ R _dokbe greater than j carrier wave C _jtime, k comparator output high level, as k modulating wave R of the first brachium pontis _lak+ 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 ₀₁j power switch unit SM _b01jsecond switch pipe S ₂the control level S of gate pole _b01j; 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 _0kj power switch unit SM _b0kjsecond switch pipe S ₂the control level S of gate pole _b0kj, 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 _{0 (N+1)}j power switch unit SM _{b0 (N+1) j}second switch pipe S ₂the control level S of gate pole _{b0 (N+1) j}; K modulating wave R of the second brachium pontis _lbk+ R _dokwith j carrier wave C _jby N+k comparator, as k modulating wave R of the second brachium pontis _lbk+ 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 _lbk+ 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 ₁₁j power switch unit SM _b11jsecond switch pipe S ₂the control level S of gate pole _b11j; 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 _1kj power switch unit SM _b1kjsecond switch pipe S ₂the control level S of gate pole _b1kj, 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 _{1 (N+1)}j power switch unit SM _{b1 (N+1) j}second switch pipe S ₂the control level S of gate pole _{b1 (N+1) j}.

Each brachium pontis that the utility model can guarantee described inverter 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

with

wherein E is the electric capacity (C of each power switch unit of each switches set of the first brachium pontis and the second brachium pontis _sM) voltage, and have E=U _dc/ n.

Take three output single-phase eight switches set nine level MMC inverters as example, Fig. 4 a illustrates that it works in the 1st modulating wave R of the first brachium pontis under CF pattern _la1+ R _do1, the first brachium pontis the 2nd modulating wave R _la2+ R _do1, the first brachium pontis the 3rd modulating wave R _la3+ R _do1with j carrier wave C _jrelation.Can find out the 1st sinusoidal wave R of the first brachium pontis from Fig. 4 a _la1, the first brachium pontis the 2nd sinusoidal wave R _la2the 3rd the sinusoidal wave R with the first brachium pontis _la3frequency identical, amplitude is not identical.Fig. 4 b illustrates that it works in the 1st modulating wave R of the first brachium pontis under DF pattern _la1+ R _do1, the first brachium pontis the 2nd modulating wave R _la2+ R _do1, the first brachium pontis the 3rd modulating wave R _la3+ R _do1with j carrier wave C _jrelation.Can find out the 1st sinusoidal wave R of the first brachium pontis from Fig. 4 b _la1, the first brachium pontis the 2nd sinusoidal wave R _la2the 3rd the sinusoidal wave R with the first brachium pontis _la3frequency and amplitude all not identical.The 1st the 1st modulating wave R of the second brachium pontis _lb1+ R _do1, the second brachium pontis the 2nd modulating wave R _lb2+ R _do1, the second brachium pontis the 3rd modulating wave R _lb3+ R _do1with j carrier wave C _jrelation and the first brachium pontis the 1st modulating wave R _la1+ R _do1, the first brachium pontis the 2nd modulating wave R _la2+ R _do1, the first brachium pontis the 3rd modulating wave R _la3+ R _do1with j carrier wave C _jrelation identical.

Fig. 5 a is the simulation waveform figure that three output single-phase eight switches set nine level MMC inverters work in CF pattern, the voltage of the electric current of the voltage of the electric current of the voltage of the 1st load, the 1st load, the 2nd load, the 2nd load, the 3rd load and the electric current of the 3rd load from top to bottom successively, identical with the power frequency of the 3rd load from visible the 1st load of Fig. 5 a, the 2nd load, the current amplitude of the 1st load, the 2nd load and the 3rd load is not identical; Fig. 5 b is the simulation waveform figure that three output single-phase eight switches set nine level MMC inverters work in DF pattern, the voltage of the electric current of the voltage of the electric current of the voltage of the 1st load, the 1st load, the 2nd load, the 2nd load, the 3rd load and the electric current of the 3rd load from top to bottom successively, all not identical from power frequency and the amplitude of visible the 1st load of Fig. 5 b, the 2nd load and the 3rd load.

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 (5)

1.N output single-phase 2N+2 switches set MMC inverter, is characterized in that: comprise DC power supply (U _dc), the first brachium pontis, the second brachium pontis and N load; Described the first brachium pontis is by N+1 switches set (B ₀₁, B ₀₂..., B _{0 (N+1)}) and 2 inductance be in series, described the second brachium pontis is by N+1 switches set (B ₁₁, B ₁₂..., B _{1 (N+1)}) and 2 inductance be in series; I switches set (B of the first brachium pontis _0i) by n power switch unit (SM _b0i1, SM _b0i2..., SM _b0in) be in series, i switches set (B of the second brachium pontis _1i) by n power switch unit (SM _b1i1, SM _b1i2..., SM _b1in) be in series, wherein the value of i is 1 ~ N+1; The two ends of k load respectively with k+1 switches set (B of the first brachium pontis _{0 (k+1)}) upper end (o) and k+1 switches set (B of the second brachium pontis _{1 (k+1)}) upper end (o) connect, wherein the value of k is 1 ~ N-1; N switches set (B of the first brachium pontis received respectively at the two ends of N load _0N) lower end (p) and N switches set (B of the second brachium pontis _1N) lower end (p); The two ends of k load are as the output of k road, and wherein the value of k is 1 ~ N, N>2, and n is positive integer.

2. N output single-phase 2N+2 switches set MMC inverter according to claim 1, is characterized in that: two inductance (L of the first brachium pontis ₀₁and L ₀₂) intercouple, form a pair of coupling inductance; Two inductance (L of the second brachium pontis ₁₁and L ₁₂) intercouple, form a pair of coupling inductance.

3. N output single-phase 2N+2 switches set MMC inverter according to claim 1, is characterized in that: DC power supply (U _dc) the upper end (o) of the 1st switches set of upper end (o), the second brachium pontis of positive pole and the 1st switches set of the first brachium pontis be connected; The 1st switches set (B of the first brachium pontis ₀₁) the 1st inductance (L of lower end (p) and the first brachium pontis ₀₁) one end connect, the 1st inductance (L of the first brachium pontis ₀₁) the other end and the 2nd switches set (B of the first brachium pontis ₀₂) upper end (o) connect; I switches set (B of the first brachium pontis _0i) i+1 switches set (B of lower end (p) and the first brachium pontis _{0 (i+1)}) upper end (o) connect, wherein the value of i is 2 ~ N-1; N switches set (B of the first brachium pontis _0N) the 2nd inductance (L of lower end (p) and the first brachium pontis ₀₂) one end connect, the 2nd inductance (L of the first brachium pontis ₀₂) the other end and N+1 switches set (B of the first brachium pontis _{0 (N+1)}) upper end (o) connect; The circuit structure of the circuit structure of the second brachium pontis and the first brachium pontis is in full accord; The two ends of k load respectively with k+1 switches set (B of the first brachium pontis _{0 (k+1)}) upper end (o) and k+1 switches set (B of the second brachium pontis _{1 (k+1)}) upper end (o) connect, wherein the value of k is 1 ~ N-1; N switches set (B of the first brachium pontis received respectively at the two ends of N load _0N) lower end (p).

4. N output single-phase 2N+2 switches set MMC inverter according to claim 1, is characterized in that: power switch unit is by the first switching tube (S ₁), second switch pipe (S ₂), the first diode (D ₁), the second diode (D ₂) and electric capacity (C _sM) form; Wherein, 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, 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.

5. N output single-phase 2N+2 switches set MMC inverter according to claim 1, is characterized in that: i switches set (B of the first brachium pontis _0i) j power switch unit (SM _b0ij) the second output and i switches set (B of the first brachium pontis _0i) j+1 power switch unit (SM _{b0i (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 _1i) j power switch unit (SM _b1ij) the second output and i switches set (B of the first brachium pontis _1i) j+1 power switch unit (SM _{b1i (j+1)}) first output connect.

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