CN102195491A - Method for reducing switching loss of matrix converter - Google Patents

Abstract

The invention discloses a method for reducing switching loss of a matrix converter. In any one dual-side modulation period, the sequence of output phases connected with input phases is regulated so that each output phase is always sequentially connected with three input phase voltages according to the instantaneous value of the input voltage in accordance with the sequence of low voltage, medium voltage, high voltage, medium voltage and low voltage, and meanwhile, action time of the output phases connected with the input phases is correspondingly regulated, therefore, the switching loss in the whole modulation period reaches the minimum. On the premise of no change of the action time of the output phases connected with the three input phases, the modulation sequence is only regulated, thus the method is simple and easy to operate; and the switching loss of the matrix converter during operation is greatly reduced.

Description

A kind of method that reduces the matrix converter switching loss

Technical field

The present invention relates to a kind of method that reduces the switching loss of matrix converter.

Background technology

Three-phase matrix converter is combined according to 3 * 3 switch matrix forms by 9 two-way power switch, as shown in Figure 1.S wherein _Ij(i=a, b, c; J=A, B, C) two-way power switch of expression, each two-way power switch adopts " common emitter " structure to constitute by two insulated gate electrode two-stage transistors (IGBT) with inverse parallel diode, also can adopt " common emitter " structure to constitute by two antiparallel inverse-impedance type IGBT.The input side of matrix converter is a three phase network voltage, uses u respectively _a, u _b, u _cExpression is connected to input filter between matrix converter and electrical network.The outlet side of matrix converter is used A respectively, and B, C represent, connect alternating current machine or inductive load equipment usually.By to 9 two-way power switch break-make controls, can realize all transformable output voltage of amplitude and frequency.

9 two-way power switch break-makes change can produce 27 kinds of on off states, uses 3 one group letter representation usually.As: abb, the output A of representing matrix converter are mutually by two-way power switch S _AAA is connected with input, and output B is mutually by two-way power switch S _BBB is connected with input, and output C is mutually by two-way power switch S _BCB is connected with input.27 corresponding 24 effective vector switch states and 3 zero vector on off states of producing of on off state.

According to the basic principle of space vector modulation method, the interval and desired output voltage vector interval by input current vector, can determine 4 effective vector switch states in each modulation period, 3 zero vector on off states and corresponding action time T ₁, T ₂, T ₃, T ₄, T ₀₁, T ₀₂, T ₀₃, and then control the turn-on and turn-off of 9 two-way power switch, realize control to matrix converter.Wherein, the modulation order of 4 effective vector switch states is arranged according to the switch switching times is minimum; And the selection of 3 zero vectors and modulation order can be arranged according to the principle of eliminating burst pulse.The concrete principle of eliminating burst pulse can be referring to the patent (application number 200910063082.3) " a kind of space vector modulating method that reduce narrow-pulse phenomenon of matrix converter " of people such as Lin Hua in application in 2009, and this method does not belong to scope of the present invention.

The output voltage vector interval of matrix converter and the division in input current vector interval are as shown in Figure 2.With output voltage vector and input current vector is example in 1 interval all, and the modulation order when adopting double-edge modulation is: bbb-abb-aab-aaa-aac-acc-ccc-acc-aac-aaa-aab-abb-bbb, and shown in Fig. 3 a.Sum action time of 7 kinds of on off states is T modulation period _s, they are with whole T _sVertically cutting.And when matrix converter at each of T modulation period _sIn carry out on off state when switching, for each output phase, all be to connect different input phase voltages successively by the period according to certain rules.Go up mutually from each output, the order that output whenever is connected to the input three-phase is u _b→ u _a→ u _c→ u _a→ u _b, just each output time of import phase that is connected has nothing in common with each other, and these times are exported action time from transverse observation, T for each _AA, T _BA, T _CA, T _AB, T _BB, T _CB, T _AC, T _BC, T _CC, amount to 9, shown in Fig. 3 b.

Because output voltage is selected between input voltage, is switched, and inevitably can bring switching loss.The lifting process of semiconductor switch device its collector voltage, electric current in the process of turning on and off is very complicated, thinks approx usually to change according to linear rule in analysis.Usually IGBT's turns on and off the function of loss for its on state current and the extreme voltage product of off-state c-e.Under the hard switching pattern, single tube single turn-on consumption ENERGY E _OnWith the turn-off power loss ENERGY E _OffBe respectively:

E _on＝U _{ce_off}I _ont _on/2

E _off＝U _{ce_off}I _ont _off/2

In the following formula, U _{Ce_off}Be respectively the voltage of IGBT when being in off-state, I _OnElectric current when being in on-state for IGBT, t _OnAnd t _OffBe respectively the time of turning on and off.

Under same output current situation, the extreme voltage of IGBT off-state c-e is more little, and the switching loss that causes is just more little.In input current vector 1 interval, the output three-phase voltage is all according to u _b→ u _a→ u _c→ u _a→ u _bModulation order switch, and three-phase input voltage at this moment always satisfies u _a＞u _b, u _a＞u _cCondition, on arbitrary output voltage, all can produce low (in) pressure → high pressure → in (low) pressure → high pressure → low (in) modulation order of pressing, this order mesohigh Switched voltage difference maximum between the low pressure, switching loss are also maximum, wherein also comprise the switching loss that some are unnecessary.

Summary of the invention

Goal of the invention: the objective of the invention is to the deficiency at above-mentioned technology, a kind of control method that reduces the matrix converter switching loss is provided, this control method can reduce the switching loss of matrix converter effectively, improves its conversion efficiency.

Technical scheme: the method for reduction matrix converter switching loss of the present invention, in in office one bilateral modulation period, adjustment by each input phase order that each output is connected, make each output mutually always according to input voltage instantaneous value size, order according to low pressure → middle pressure → high pressure → middle pressure → low pressure connects 3 input phase voltages successively, thereby guarantees that the switching loss in whole modulation period reaches minimum.

The present invention compared with prior art, its beneficial effect is: the present invention known determined traditional modulation order and corresponding ON time after, modulation order and corresponding ON time are adjusted, adopt the modulation order of low pressure → middle pressure → high pressure → middle pressure → low pressure, make output voltage between less input voltage, switch all the time, avoided high pressure

The modulation order of low pressure greatly reduces the switching loss of system.The present invention does not need to increase extra hardware circuit and control, only needs to adjust the modulation order of each output phase, and method is simple.

Description of drawings

Fig. 1 is the topology diagram of three-phase matrix converter.

Fig. 2 is the division figure in output voltage vector interval and input current vector interval.

Output phase voltage waveform when Fig. 3 is traditional space vector double-edge modulation.

Fig. 4 is the flow process of the invention process method.

Fig. 5 is r, s, t and input a, b, the corresponding relation of c phase, U, V, W and output A, B, the corresponding relation of C phase.

Fig. 6 is for adjusting the comparison of wave shape figure of modulation order front and back.

Fig. 7 is for adopting the enforcement schematic diagram that the invention provides example.

Embodiment

Below in conjunction with accompanying drawing, technical solution of the present invention is elaborated, but protection scope of the present invention is not limited to described embodiment.

Embodiment: a kind of method that reduces the matrix converter switching loss, in in office one bilateral modulation period, adjust each output be connected each the input phase order, make each output mutually always according to input voltage instantaneous value size, order according to low pressure → middle pressure → high pressure → middle pressure → low pressure connects 3 input phase voltages successively, thereby guarantees that the switching loss in whole modulation period reaches minimum.The inventive method makes output voltage switch between less input voltage all the time, its objective is and avoids high pressure

The modulation order of low pressure rationally reduces the switching loss of system.

As shown in Figure 4, the specific implementation step of this method comprises:

(1), determines each of T according to traditional space vector modulation principle with optimize the switch number of times, eliminate the principle of burst pulse modulation period _sOn off state and 3 zero vector on off states of interior 4 effective vectors, and T action time of calculating and 7 on off state correspondences of reasonable disposition ₁, T ₂, T ₃, T ₄, T ₀₁, T ₀₂, T ₀₃, guarantee T simultaneously ₁+ T ₂+ T ₃+ T ₄+ T ₀₁+ T ₀₂+ T ₀₃=T _s

(2) each output connects 3 action times of importing phases mutually respectively in this modulation period according to calculating 7 on off states and corresponding action time, when output is 3 phase times mutually, should obtain 9 action times altogether;

With output voltage vector interval and input current vector interval is example in 1 interval all.On off state and 3 zero vector on off states of 4 effective vectors that produce are respectively abb, aab, aac, acc, bbb, aaa, ccc, and be T corresponding action time ₁, T ₂, T ₃, T ₄, T ₀₁, T ₀₂, T ₀₃, Fig. 3 a is its three-phase output waveform figure.By above-mentioned state and time, with reference to the corresponding relation of Fig. 3 a, Fig. 3 b, can calculate the action times that each output connects 3 input phases mutually respectively, amount to 9 as follows:

T _bA＝T ₀₁，T _aA＝T ₁+T ₂+T ₀₂+T ₃+T ₄，T _cA＝T ₀₃；

T _bB＝T ₀₁+T ₁，T _aB＝T ₂+T ₀₂+T ₃，T _cA＝T ₄+T ₀₃；

T _bC＝T ₀₁+T ₁+T ₂，T _aB＝T ₀₂，T _cA＝T ₃+T ₄+T ₀₃。

Above-mentioned time relationship is generalized to the interval and interval combined situation of input current vector of different input voltage vector, can be as shown in the formula 9 action times of calculating:

T _rU＝T ₀₁，T _sU＝T ₁+T ₂+T ₀₂+T ₃+T ₄，T _tU＝T ₀₃；

T _rV＝T ₀₁+T ₁，T _sV＝T ₂+T ₀₂+T ₃，T _tV＝T ₄+T ₀₃；

T _rW＝T ₀₁+T ₁+T ₂，T _sW＝T ₀₂，T _tW＝T ₃+T ₄+T ₀₃。

Under different input voltage vector intervals and the interval situation of input current vector, 9 action times and the corresponding relation difference of 7 vector states between action time, r in the following formula, s, t and input three-phase voltage a, b, the corresponding relation of c, U, V, W and output three-phase voltage A, B, the corresponding relation of C as shown in Figure 5.

(3) detect the relatively instantaneous value size of 3 phase input voltages, determine the low pressure in the input voltage, middle pressure, high pressure;

(4) modulation order of low pressure → middle pressure → high pressure → middle pressure → low pressure is adopted in each output mutually, connects 3 input phases successively, and corresponding adjustment simultaneously connects the action time of each input phase, and should try to achieve these action times according to step (2);

Be example all with output voltage vector interval and input current vector interval equally in 1 interval.According to traditional space vector modulation mode and step (2), can get each output and all adopt u mutually _b→ u _a→ u _c→ u _a→ u _bModulation order, be its corresponding action time in proper order:

Output A phase T _BA/ 2 → T _AA/ 2 → T _CA→ T _AA/ 2 → T _BA/ 2;

Output B phase T _BB/ 2 → T _AB/ 2 → T _CB→ T _AB/ 2 → T _BB/ 2;

Output C phase T _BC/ 2 → T _AC/ 2 → T _CCj→ T _AC/ 2 → T _BC/ 2.

Suppose that the input voltage magnitude relationship that step (3) detects is u _b＜u _c＜u _a, the modulation order of employing step (4) mesolow → middle pressure → high pressure → middle pressure → low pressure, the modulation order that each should be exported phase is adjusted into u _b→ u _c→ u _a→ u _c→ u _b, also change into its corresponding action time in proper order:

Output A phase T _BA/ 2 → T _CA/ 2 → T _AA→ T _CA/ 2 → T _BA/ 2;

Output B phase T _BB/ 2 → T _CB/ 2 → T _AB→ T _CB/ 2 → T _BB/ 2;

Output C phase T _BC/ 2 → T _CC/ 2 → T _AC→ T _CC/ 2 → T _BC/ 2.

Output voltage waveforms before and after adjusting as shown in Figure 6.Be generalized to ordinary circumstance, under different input voltage vector intervals and input current vector interval, modulation order of each output phase should be adjusted into u _x→ u _y→ u _z→ u _y→ u _x, u wherein _x＜u _y＜u _z, x, y, z ∈ a, b, c, x ≠ y ≠ z.Be adjusted into its corresponding action time in proper order:

Output A phase T _XA/ 2 → T _YA/ 2 → T _ZA→ T _YA/ 2 → T _XA/ 2;

Output B phase T _XB/ 2 → T _YB/ 2 → T _ZB→ T _YB/ 2 → T _XB/ 2;

Output C phase T _XC/ 2 → T _YC/ 2 → T _ZC→ T _YC/ 2 → T _XC/ 2.

(5) according to adjusting each output of back the be connected order of each input phase and the turn-on and turn-off of arranging each two-way power switch action time, realize change of current control.

The enforcement of above-mentioned adjustment modulator approach as shown in Figure 7, wherein step (1) and (2) are realized by digital signal processor DSP TMS320F28335, control program C language compilation, step (3)～(5) realize that by on-site programmable gate array FPGA EP2C8T144C8 wherein step (5) change of current control circuit control program is a prior art.

The present invention can reduce the switching loss of matrix converter largely.Interval and input current vector interval is all in 1 interval with output voltage vector, and load current I _On＞0 is example.Original certain output phase modulated process is

U wherein _b＜u _c＜u _a, then the off-state pressure reduction before and after four changes of current is respectively u _AbAnd u _AcBecause output change of current between input mutually respectively can produce and turn on and off operation twice, so the switching loss energy of this output in single modulation period is:

E _SVM1＝E _b→a(on)+E _a→c(off)+E _c→a(on)+E _a→b(off)

$=\frac{u_{\mathrm{ab}}{I}_{\mathrm{on}}(t_{\mathrm{on}}+t_{\mathrm{off}})}{2}+\frac{u_{\mathrm{ac}}{I}_{\mathrm{on}}(t_{\mathrm{on}}+t_{\mathrm{off}})}{2}<u_{\mathrm{ab}}{I}_{\mathrm{on}}(t_{\mathrm{on}}+t_{\mathrm{off}})$

After adjusting modulation order, modulated process becomes

Off-state pressure reduction before and after twice change of current is respectively u _CbAnd u _AcAt this moment the switching loss energy of this output in single modulation period is:

E _SVM2＝E _b→c(on)+E _c→a(on)+E _a→c(off)+E _c→b(off)

$=\frac{u_{\mathrm{cb}}{I}_{\mathrm{on}}(t_{\mathrm{on}}+t_{\mathrm{off}})}{2}+\frac{u_{\mathrm{ac}}{I}_{\mathrm{on}}(t_{\mathrm{of}}+t_{\mathrm{off}})}{2}$

$=\frac{u_{\mathrm{ab}}{I}_{\mathrm{on}}(t_{\mathrm{on}}+t_{\mathrm{off}})}{2}$

Inductive load is output current I in single modulation period _OnRemain unchanged, and u _Ac＜u _Ab, therefore adjusted order can reduce the loss of half at the most.

As mentioned above, although represented and explained the present invention that with reference to specific preferred embodiment it shall not be construed as the restriction to the present invention self.Under the spirit and scope of the present invention prerequisite that does not break away from the claims definition, can make various variations in the form and details to it.

Claims (2)

1. method that reduces the matrix converter switching loss, it is characterized in that: in office one bilateral modulation period, adjust each output be connected each the input phase order, make each output mutually always according to input voltage instantaneous value size, order according to low pressure → middle pressure → high pressure → middle pressure → low pressure connects 3 input phase voltages successively, thereby guarantees that the switching loss in whole modulation period reaches minimum.

2. the method for reduction matrix converter switching loss according to claim 1 is characterized in that, the specific implementation step of this method comprises:

(1), determines each of T according to traditional space vector modulation principle with optimize the switch number of times, eliminate the principle of burst pulse modulation period _sOn off state and 3 zero vector on off states of interior 4 effective vectors, and T action time of calculating and 7 on off state correspondences of reasonable disposition ₁, T ₂, T ₃, T ₄, T ₀₁, T ₀₂, T ₀₃, guarantee T simultaneously ₁+ T ₂+ T ₃+ T ₄+ T ₀₁+ T ₀₂+ T ₀₃=T _s

(2) each output connects 3 action times of importing phases mutually respectively in this modulation period according to calculating 7 on off states and corresponding action time, when output is 3 phase times mutually, should obtain 9 action times altogether;

(3) detect the relatively instantaneous value size of 3 phase input voltages, determine the low pressure in the input voltage, middle pressure, high pressure;

(4) modulation order of low pressure → middle pressure → high pressure → middle pressure → low pressure is adopted in each output mutually, connects 3 input phases successively, and corresponding adjustment simultaneously connects the action time of each input phase, and should try to achieve these action times according to step (2);

(5) according to adjusting each output of back the be connected order of each input phase and the turn-on and turn-off of arranging each two-way power switch action time, realize change of current control.

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