CN203872080U - Dual-output single-phase three-switch-group MMC inverter without direct current bias - Google Patents

Abstract

The utility model provides a dual-output single-phase six-switch-group MMC inverter without direct current bias. The inverter comprises a direct current power supply, a first capacitor, a second capacitor, a third capacitor, a switch bridge arm, a first load and a second load. The switch bridge arm is formed through series connection of an upper switch group, a middle switch group, a lower switch group and a coupling inductor. The upper switch group, the middle switch group and the lower switch group are formed through series connection of N power switch units respectively. One end of the first load is connected with the middle points of the first capacitor and the second capacitor. The other end of the first load is connected with the upper end of the middle switch group. One end of the second load is connected with the middle points of the second capacitor and the third capacitor. The other end of the second load is connected with the lower end of the middle switch group. The inverter employs carrier phase-shifting PWM control, and can output two alternating current voltages of N+1 levels without direct current bias. The inverter is suitable for occasions with high voltage, large power and dual loads. The coupling inductor in the inverter can be replaced by two independent inductors.

Description

Without the single-phase three switches set MMC inverters of dual output of direct current biasing

Technical field

The module that relates to the utility model combines many level (MMC) converter field, is specifically related to the single-phase three switches set MMC inverters of a kind of dual output without direct current biasing.

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 three switch converters have reduced a switch and corresponding drive circuit with respect to four traditional switch converters, in the application of considering cost and volume, occupy certain advantage.But the single-phase output of two-way of three switch converters is two level, output AC waveform is poor.In addition, the half that the voltage stress that in three switches, each switch bears is DC bus-bar voltage, and the voltage-sharing of three switching tubes of existence, this has limited the application of single-phase three 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 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 alternating current circuit of two different frequencies connected, needing 2 MMC converters, 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 the single-phase three switches set MMC inverters of a kind of dual output without direct current biasing.

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

The single-phase three switches set MMC inverters of dual output without direct current biasing comprise DC power supply, the first electric capacity, the second electric capacity, the 3rd electric capacity, switch brachium pontis, the first load and the second load; Described switch brachium pontis is by upper switches set, middle switches set, lower switches set and coupling inductance series connection; Upper switches set is in series into by N power switch unit, and middle switches set is in series by N power switch unit, and lower switches set is in series by N power switch unit; One end of the first load is received the mid point of the first electric capacity, the second electric capacity, and the other end of the first load is received the upper end of middle switches set; One end of the second load is received the mid point of the second electric capacity, the 3rd electric capacity, and the other end of the second load is received the lower end of middle switches set; Export as the first via at the two ends of the first load, and export as the second tunnel at the two ends of the second load; The voltage of the first electric capacity, the second electric capacity and the 3rd electric capacity is U _dc/ 3.The former secondary of coupling inductance is substituted by the first inductance and two separate inductors of the second inductance.Adopt phase-shifting carrier wave PWM to control the opening and turn-offing of switching tube of upper switches set, middle switches set and lower switches set in described converter.

In the single-phase three switches set MMC inverters of the above-mentioned dual output without direct current biasing, in the single-phase three switches set MMC inverters of the described dual output without direct current biasing, the positive pole of the positive pole of DC power supply and the first electric capacity, the upper end of upper switches set connects, the lower end of upper switches set is connected with the Same Name of Ends on the former limit of coupling inductance, the non-same polarity on the former limit of coupling inductance is connected with the upper end of middle switches set, the lower end of middle switches set is connected with the Same Name of Ends of coupling inductance secondary, the non-same polarity of coupling inductance secondary is connected with the upper end of lower switches set, the negative pole of the lower end of lower switches set and the 3rd electric capacity, the negative pole of DC power supply, ground end connects, the positive pole of the 3rd electric capacity is connected with the negative pole of the second electric capacity, the positive pole of the second electric capacity is connected with the negative pole of the first electric capacity, one end of the first load is connected with the upper end of middle switches set, and the other end of the first load is connected with the positive pole of the second electric capacity, and one end of the second load is connected with the lower end of middle switches set, and the other end of b road load is connected with the negative pole of the second electric capacity.

In the single-phase three switches set MMC inverters of the above-mentioned dual output without direct current biasing, 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.

In the single-phase three switches set MMC inverters of the above-mentioned dual output without direct current biasing, the second output of i power switch unit of upper switches set is connected with the first output of i+1 power switch unit, and wherein i value is 1～N-1; The second output of i power switch unit of middle switches set is connected with the first output of i+1 power switch unit; The second output of i power switch unit of lower switches set is connected with the first output of i+1 power switch unit.

In the control method of the single-phase three switches set MMC inverters of the above-mentioned dual output without direct current biasing, in employing phase-shifting carrier wave PWM control, the switching tube of switches set, middle switches set and lower switches set opening and turn-offing; I power switch unit of upper switches set and i power switch unit of lower switches set adopt identical triangular wave as i carrier wave C _i, wherein i value is 1～N; N carrier wave 360 °/N of lagging phase angle successively; The direct current biasing that first via output employing sine-wave superimposed value is 1/3 is as the first modulating wave R _athe direct current biasing that the+1/3, second tunnel output employing sine-wave superimposed value is 1/3 is as the second modulating wave R _b-1/3.

In above-mentioned control method, the first modulating wave R _a+ 1/3 and i carrier wave C _iobtain the control level of the second switch pipe gate pole of i power switch unit of upper switches set by the first comparator, as the first modulating wave R _a+ 1/3 is greater than i carrier wave C _itime, the first comparator output high level, as the first modulating wave R _a+ 1/3 is less than i carrier wave C _itime, the first comparator output low level, wherein the value of i is 1～N; The second modulating wave R _b-1/3 and i carrier wave C _iobtain the control level of the second switch pipe gate pole of i power switch unit of lower switches set by the second comparator, as the second modulating wave modulating wave R _b-1/3 is less than i carrier wave C _itime, the second comparator output high level, as the second modulating wave modulating wave R _b-1/3 is greater than i carrier wave C _itime, the second comparator output low level; The control level of the control level of second switch pipe gate pole of i power switch unit of upper switches set and the second switch pipe gate pole of i power switch unit of lower switches set obtains the control level of second switch pipe gate pole in i power switch unit of middle switches set by XOR gate; In each power switch unit of each switches set, the control level of second switch pipe gate pole obtains the control level of the first switching tube gate pole of this power switch unit after anti-phase.

Comprise with mode of operation (CF pattern) and alien frequencies mode of operation (DF pattern) frequently without the mode of operation of the single-phase three switches set MMC inverters of dual output of direct current biasing, in CF pattern, first via output is identical with the frequency of the second tunnel output, and amplitude is not identical; In DF pattern, frequency and the amplitude of first via output and the output of the second tunnel are all not identical.

Compared with prior art, the advantage the utlity model has is: have two-way N+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 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 single-phase three switch converters, the two-way output of the single-phase three switches set MMC inverters of the dual output without direct current biasing provided by the utility model is N+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 in high pressure and large-power occasions without the single-phase three switches set MMC inverters of dual output of direct current biasing.Compare with existing MMC converter, the single-phase three switches set MMC inverters of the dual output without direct current biasing provided by the utility model have two-way exchange output, can be directly used in two different frequencies alternating current circuit be connected, greatly reduce engineering cost.

Brief description of the drawings

Fig. 1 is the circuit structure diagram of the single-phase three switches set MMC inverters of the dual output without direct current biasing of the present utility model;

Fig. 2 is the circuit structure diagram of the power switch unit of the single-phase three switches set MMC inverters of the dual output without direct current biasing of the present utility model;

Fig. 3 is the structure chart of the phase-shifting carrier wave PWM control method of the single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1;

Fig. 4 a, 4b are that the single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1 work in respectively CF pattern and the modulating wave of DF pattern and the relation of carrier wave;

Fig. 5 a, 5b are the simulation waveform figure that works in respectively CF pattern and DF pattern without the single-phase five level three switches set MMC inverters of dual output of direct current biasing.

Embodiment

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

With reference to figure 1, the single-phase three switches set MMC inverters of the dual output without direct current biasing of the present utility model, comprise DC power supply U _dc, the first capacitor C ₁, the second capacitor C ₂, the 3rd capacitor C ₃, switch brachium pontis, the first load and the second load; Described switch brachium pontis is by upper switches set H, middle switches set M, lower switches set L and coupling inductance (L _h: L _l) be in series; Upper switches set H is by N power switch unit (SM _h1, SM _h2..., SM _hN) be in series, middle switches set M is by N power switch unit (SM _m1, SM _m2..., SM _mN) be in series, lower switches set L is by N power switch unit (SM _l1, SM _l2..., SM _lN) be in series; One end of the first load is received the first capacitor C ₁, the second capacitor C ₂mid point, the other end of the first load is received the upper end o of middle switches set M; One end of the second load is received the second capacitor C ₂, the 3rd capacitor C ₃mid point, the other end of the second load is received the lower end p of middle switches set M; Export as the first via at the two ends of the first load, and export as the second tunnel at the two ends of the second load; The first capacitor C ₁, the second capacitor C ₂with the 3rd capacitor C ₃voltage be U _dc/ 3.Wherein, DC power supply U _dcpositive pole and the first capacitor C ₁the upper end o of positive pole, upper switches set H connect, the lower end p of upper switches set H and coupling inductance (L _h: L _l) former limit L _hsame Name of Ends w connect, coupling inductance (L _h: L _l) former limit L _hnon-same polarity a be connected with the upper end o of middle switches set M, the lower end p of middle switches set M and coupling inductance (L _h: L _l) secondary L _lsame Name of Ends b connect, coupling inductance (L _h: L _l) secondary L _lnon-same polarity z be connected with the upper end o of lower switches set L, the lower end p of lower switches set L and the 3rd capacitor C ₃negative pole, DC power supply U _dcnegative pole, hold n connect, the 3rd capacitor C ₃positive pole and the second capacitor C ₂negative pole connect, the second capacitor C ₂positive pole and the first capacitor C ₁negative pole connect; One end of the first load is connected with the upper end o of middle switches set M, the other end of the first load and the second capacitor C ₂positive pole connect, one end of the second load is connected with the lower end p of middle switches set M, the other end of b road load and the second capacitor C ₂negative pole connect.

Fig. 2 illustrates the circuit structure diagram of the power switch unit of the single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1.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 _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 the power switch unit SM of upper switches set H _hithe second output and i+1 power switch unit SM _{h (i+1)}first output connect, wherein i value is 1～N-1; I the power switch unit SM of middle switches set M _mithe second output and i+1 power switch unit SM _{m (i+1)}first output connect; I the power switch unit SM of lower switches set L _lithe second output and i+1 power switch unit SM _{l (i+1)}first output connect.

As shown in Figure 1, the both end voltage of the first load and the second load is respectively:

$\left\{\begin{array}{c}{u}_a=u_{\mathrm{an}}-\frac{2}{3}{U}_{\mathrm{dc}}=\frac{u_L+u_M-u_H}{2}-\frac{1}{6}{U}_{\mathrm{dc}}\\ u_b=u_{\mathrm{bn}}-\frac{1}{3}{U}_{\mathrm{dc}}=\frac{u_L-u_M-u_H}{2}+\frac{1}{6}{U}_{\mathrm{dc}}\end{array}\right.$

In formula, u _hfor the output voltage of upper switches set (H), u _mfor the output voltage of upper switches set (M), u _lfor the output voltage of lower switches set (L).

Again:

$\frac{U_{\mathrm{dc}}/6}{U_{\mathrm{dc}}/2}=\frac{1}{3}---\left(6\right)$

Known according to formula (6), the direct current biasing that first via output employing sine-wave superimposed value is 1/3 is as the first modulating wave R _athe direct current biasing that the+1/3, second tunnel output employing sine-wave superimposed value is 1/3 is as the second modulating wave R _b-1/3.

The single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1 adopt phase-shifting carrier wave PWM to control, as shown in Figure 3.The first modulating wave R _a+ 1/3 and i carrier wave C _iobtain i the power switch unit SM of upper switches set H by the first comparator _hjsecond switch pipe S ₂the control level S of gate pole _hi, as the first modulating wave R _a+ 1/3 is greater than i carrier wave C _itime, the first comparator output high level, as the first modulating wave R _a+ 1/3 is less than i carrier wave C _itime, the first comparator output low level, wherein the value of i is 1～N; The second modulating wave R _b-1/3 and i carrier wave C _iobtain i the power switch unit SM of lower switches set L by the second comparator _lisecond switch pipe S ₂the control level S of gate pole _li, as the second modulating wave modulating wave R _b-1/3 is less than i carrier wave C _itime, the second comparator output high level, as the second modulating wave modulating wave R _b-1/3 is greater than i carrier wave C _itime, the second comparator output low level; I the power switch unit SM of upper switches set H _hjsecond switch pipe S ₂the control level S of gate pole _hii the power switch unit SM with lower switches set L _lisecond switch pipe S ₂the control level S of gate pole _liobtain i the power switch unit SM of middle switches set M by XOR gate _mimiddle second switch pipe S ₂the control level S of gate pole _mi; Second switch pipe S in each power switch unit of each switches set ₂after the control level of gate pole is anti-phase, obtain the first switching tube S of this power switch unit ₁the control level of gate pole.

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 2N the true unit of power _sM=0, meet U _h+ U _m+ U _l=U _dc, wherein E is electric capacity (C in each power switch unit _sM) on voltage, and have E=U _dc/ N.

Fig. 4 a illustrates that the single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1 work in the first modulating wave R under CF pattern _a+ 1/3, the second modulating wave R _b-1/3 and i carrier wave C _irelation.Can find out from Fig. 4 a, first via output is identical with the electric voltage frequency of the second tunnel output, and the voltage magnitude maximum of first via output and the output of the second tunnel is 2/3.Fig. 4 b illustrates that the single-phase three switches set MMC inverters of the dual output without direct current biasing shown in Fig. 1 work in the first modulating wave R under DF pattern _a+ 1/3, the second modulating wave R _b-1/3 and i carrier wave C _irelation.Can find out from Fig. 4 b, the electric voltage frequency of first via output and the output of the second tunnel is not identical, and the voltage magnitude of first via output and the output of the second tunnel is 1/3 to the maximum.

Fig. 5 a is the simulation waveform figure that the single-phase five level three switches set MMC inverters of dual output work in CF pattern, the voltage of the first load, voltage, the electric current of the first load and the electric current of the second load of the second load from top to bottom successively, identical with the power frequency of the second load from visible the first load of Fig. 5 a, the current amplitude of the first load and the second load is not identical; Fig. 5 b is the simulation waveform figure that the single-phase five level three switches set MMC inverters of dual output work in DF pattern, be successively from top to bottom the voltage of the first load, voltage, the electric current of the first load and the electric current of the second load of the second load, all not identical from power frequency and the amplitude of visible the first load of Fig. 5 b and the second load.

Above-described embodiment is preferably execution mode of the utility model; 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. without the single-phase three switches set MMC inverters of dual output of direct current biasing, it is characterized in that: comprise DC power supply (U _dc), the first electric capacity (C ₁), the second electric capacity (C ₂), the 3rd electric capacity (C ₃), switch brachium pontis, the first load and the second load; Described switch brachium pontis is in series by upper switches set (H), middle switches set (M), lower switches set (L) and coupling inductance; Upper switches set (H) is by N power switch unit (SM _h1, SM _h2..., SM _hN) be in series, middle switches set (M) is by N power switch unit (SM _m1, SM _m2..., SM _mN) be in series, lower switches set (L) is by N power switch unit (SM _l1, SM _l2..., SM _lN) be in series, N is positive integer; One end of the first load is received the first electric capacity (C ₁), the second electric capacity (C ₂) mid point, the other end of the first load is received the upper end (o) of middle switches set (M); One end of the second load is received the second electric capacity (C ₂), the 3rd electric capacity (C ₃) mid point, the other end of the second load is received the lower end (p) of middle switches set (M); Export as the first via at the two ends of the first load, and export as the second tunnel at the two ends of the second load; The first electric capacity (C ₁), the second electric capacity (C ₂) and the 3rd electric capacity (C ₃) voltage be U _dc/ 3, U _dcfor the voltage of DC power supply.

2. the single-phase three switches set MMC inverters of the dual output without direct current biasing according to claim 1, is characterized in that: the former limit of coupling inductance and secondary are by the first inductance (L _h) and the second inductance (L _l) two separate inductors substitute.

3. the single-phase three switches set MMC inverters of the dual output without direct current biasing according to claim 1, is characterized in that: DC power supply (U _dc) positive pole and the first electric capacity (C ₁) the upper end of positive pole, upper switches set (H) connect, the lower end of upper switches set (H) is connected with the Same Name of Ends (w) on the former limit of coupling inductance, the non-same polarity (a) on the former limit of coupling inductance is connected with the upper end of middle switches set (M), the lower end of middle switches set (M) and coupling inductance secondary (L _l) Same Name of Ends (b) connect, the non-same polarity (z) of coupling inductance secondary is connected with the upper end of lower switches set (L), the lower end of lower switches set (L) and the 3rd electric capacity (C ₃) negative pole, DC power supply (U _dc) negative pole, hold (n) connect, the 3rd electric capacity (C ₃) positive pole and the second electric capacity (C ₂) negative pole connect, the second electric capacity (C ₂) positive pole and the first electric capacity (C ₁) negative pole connect; One end of the first load is connected with the upper end of middle switches set (M), the other end of the first load and the second electric capacity (C ₂) positive pole connect, one end of the second load is connected with the lower end of middle switches set (M), the other end of b road load and the second electric capacity (C ₂) negative pole connect.

4. the single-phase three switches set MMC inverters of the dual output without direct current biasing 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. the single-phase three switches set MMC inverters of the dual output without direct current biasing according to claim 1, is characterized in that: i power switch unit (SM of upper switches set (H) _hi) the second output and i+1 power switch unit (SM _{h (i+1)}) first output connect, wherein i value is 1 ~ N-1; I power switch unit (SM of middle switches set (M) _mi) the second output and i+1 power switch unit (SM _{m (i+1)}) first output connect; I power switch unit (SM of lower switches set (L) _li) the second output and i+1 power switch unit (SM _{l (i+1)}) first output connect.