CN100440710C - Commutator and control method thereof - Google Patents

Abstract

The present invention relates to a UPS without a transformer and a PWM rectifier control method thereof. In order to enhance the capability of driving a semi-wave load of the UPS and the capability of resisting the instantaneous short circuit of the output of the UPS and reduce the volume and the cost of a voltage homogenizing circuit under the precondition of not losing the performance index of input harmonic current, zero-sequence current (i0<*>) assigned in the UPS without a transformer is no longer a constant value 0, positive and negative bus bar voltage difference (EU) and positive and negative bus bar voltage difference (EU<*>) assigned are input to a positive and negative bus bar voltage difference regulator for carrying out the treatment of regulating on the basis of the prior art, and a current loop (Iout) assigned is generated. The assigned switching over process of the current is carried out by a double-input and single-output current assigned change-over switch, one input of the double-input and single-output current assigned change-over switch is the current loop (Iout) assigned, and the other input of the double-input and single-output current assigned change-over switch is 0. When the absolute value /EU/ of the positive and negative bus bar voltage difference is larger than a predetermined value (Uset), the current loop (Iout) assigned is used as the zero-sequence current (i0<*>) assigned and is output, and a rectifier runs in a positive and negative bus bar voltage homogenizing mode. When the absolute value /EU/ of the positive and negative bus bar voltage difference is not larger than the predetermined value (Uset), 0 is used as the zero-sequence current (i0<*>) assigned and is output, and the rectifier runs in a low current harmonic mode.

Description

Rectifier and control method thereof

Technical field

The present invention relates to UPS (uninterrupted power supply), more particularly, relate to pulse width modulation rectifier and control method thereof among the transless UPS.

Background technology

Along with the aggravation of market competition, the price cost squeeze of UPS product is increasing.Transless UPS replaces the UPS of traditional band Industrial Frequency Transformer just gradually owing to saved heavy and expensive Industrial Frequency Transformer, becomes the research and development emphasis of each big UPS manufacturer.

Transless UPS is made of rectifier, inverter, battery converter etc., and wherein rectifier is the device for converting electric energy of AC-to DC, is the middle bridge that connects electrical network and inverter.The topological structure of three-phase and four-line PWM (pulse-width modulation) rectifier among common transless UPS as shown in Figure 1.Wherein, Q1, Q2 to Q6 are the switching device of rectifier, generally also are parallel with reverse fly-wheel diode (not drawing) in the inside or the outside of each switching device in this figure; C6, C7 are bus capacitor, and the direct voltage on these two electric capacity is respectively U+, U-; L1, L2, L3 are boost inductance, and constitute filter circuit with filter capacitor C1, C2, C3; Usa, Usb, Usc are the three-phase phase voltage of electrical network.

During work, the conducting by control switch device Q1 to Q6 or end can make the waveform of input inductance current i a, ib, ic and input line voltage Usa, Usb, Usc approximate, and the phase place unanimity, thereby can realize power factor correction.

The controlling schemes of a typical three-phase and four-line PWM rectifier under rotating coordinate system as shown in Figure 2, wherein:

(1) three phase network phase voltage (Usa, Usb, Usc) draws the mould long (vd) of voltage vector and follows the tracks of angle (angle) through asking mould and phase-locked loop calculator 212;

(2) three-phase phase current (ia, ib, ic) carries out static coordinate through coordinate converter 211 and is tied to the rotating coordinate system conversion, draws active current (id), reactive current (iq) and the zero-sequence current (i0) of phase current under rotating coordinate system;

(3) given (Ud of busbar voltage ^*) and Voltage Feedback (Ud) (Ud=|U+|+|U-|) obtain voltage difference through subtracter 201, behind bus regulator 202, form the given (id of active current again ^*);

(4) given (id of active current ^*), the given (iq of reactive current ^*) and the given (i0 of zero-sequence current ^*), iq wherein ^*With i0 ^*Be generally 0, with active current (id), reactive current (iq) and the zero-sequence current (i0) of aforementioned coordinate converter 211 outputs respectively through subtracter 203,204,205 processing, obtain respectively that active current is poor, reactive current difference and zero-sequence current be poor;

(5) poor, reactive current difference of above-mentioned active current and zero-sequence current difference are handled through current regulator 206,207,208, generate the correspondent voltage amount trimmed;

(6) coordinate transform and PWM generator 210 are directly sent in the output of current regulator 207,208, and the output of current regulator 206 then by adder 209 and long (vd) addition of the mould of aforesaid voltage vector, is sent into coordinate transform and PWM generator 210 again;

(7) coordinate transform and PWM generator 210 are sent the three-phase PWM switching waveform according to corresponding input variable, drive six switching device Q1, Q2 to Q6 in the rectifier.

For UPS, input harmonic current is a very important performance index parameter.In common design, the given (i0 of zero-sequence current in the control of three-phase and four-line PWM rectifier ^*) be 0, with the zero-sequence current minimum of the rectifier that guarantees to flow through, make the index optimum of input harmonic current.As shown in Figure 3, the function of regulating the positive and negative busbar electric voltage equalization is realized by positive and negative busbar balance of voltage device 301 (part that does not belong to rectifier) independently fully.In order to save volume and cost, the capacity of positive and negative busbar balance of voltage device 301 generally designs lessly, only accounts for 10～15% of overall system capacity usually.In the multiple dynamic process of UPS work (for example rectified load input or the moment of laying down, UPS output are short-circuited the moment of fault), when the power of the half-wave composition in the UPS load surpasses the capacity of positive and negative busbar balance of voltage device 301, all may cause the undesired even inefficacy of system works, cause the consequence of outage to the user.

As seen, the above-mentioned given (i0 that makes zero-sequence current ^*) be 0 way, do not give full play to the ability that rectifier is regulated the positive and negative busbar electric voltage equalization, thereby guarantee the stable of system to greatest extent.But the rectifier of leaving is regulated the positive and negative busbar electric voltage equalization, and the performance index that can lose input harmonic current again cause the performance rate of UPS product to descend.It should be noted that, for transless UPS, when normal steady operation, do not need the ability of very big band half-wave load, and all be in various transient processes (for example rectified load input or the moment of laying down, UPS output are short-circuited the moment of fault) when really needing this ability.

Summary of the invention

At the above-mentioned defective of prior art, the technical problem to be solved in the present invention is not lose under the input harmonic current performance index prerequisite, improves the ability of UPS band half-wave load, reduces the capacity and the cost of equalizer circuit, and improves the reliability of system.

For solving the problems of the technologies described above, the invention provides a kind of rectifier, its pulse width modulation controlled unit comprises:

According to the electrical network three-phase phase voltage that is connected with described rectifier, draw the phase-locked loop calculator of following the tracks of angle;

The three-phase phase current of three boost inductances carries out static coordinate and is tied to the rotating coordinate system conversion in the convection current over commutation device, to generate first coordinate converter of active current, reactive current and zero-sequence current;

With the given positive and negative busbar absolute value of voltage sum that deducts of busbar voltage, draw first subtracter of voltage difference; Described voltage difference is regulated to generate the given bus regulator of active current.

With given second subtracter that deducts active current with generation active current difference of described active current, deduct described reactive current generating the 3rd subtracter of reactive current difference with reactive current is given, and with given the 4th subtracter that deducts described zero-sequence current with generation zero-sequence current difference of zero-sequence current;

Respectively to described second, third, poor, the reactive current difference of the active current of the 4th subtracter output and zero-sequence current difference regulate, to generate first, second, third current regulator of first, second, third voltage trim amount;

According to described first, second, third voltage trim amount, and described tracking angle, generation transforms to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, is used for driving the coordinate transform and the PWM generator of six switching devices of described rectifier;

It is characterized in that, in the pulse width modulation controlled unit of described rectifier, also comprise:

The actual positive and negative busbar voltage difference of and rectifier given according to the positive and negative busbar voltage difference generates the given positive and negative busbar voltage difference adjuster of electric current loop;

When the absolute value of described actual positive and negative busbar voltage difference during greater than predetermined value, given given with described electric current loop as zero-sequence current, otherwise with 0 as the given given diverter switch of electric current that outputs to described the 4th subtracter of zero-sequence current.

The present invention also provides a kind of control method of rectifier, it is characterized in that, controls the pulse-width modulation of rectifier by following steps:

(1) according to the electrical network three-phase phase voltage that is connected with rectifier, obtains corresponding tracking angle;

(2) the three-phase phase current of three boost inductances carries out the conversion that static coordinate is tied to rotating coordinate system in the convection current over commutation device, draws active current, reactive current and the zero-sequence current of this three-phase phase current under rotating coordinate system;

(3) with the given positive and negative busbar absolute value of voltage sum that deducts of busbar voltage, formation voltage is poor, with voltage regulator described voltage difference is regulated again, and it is given to generate active current;

(4) the positive bus-bar voltage with rectifier deducts negative busbar voltage, obtains the positive and negative busbar voltage difference, and given according to described positive and negative busbar voltage difference and positive and negative busbar voltage difference again, it is given to generate corresponding electric current loop;

(5) when the absolute value of described positive and negative busbar voltage difference during, given given as zero-sequence current with described electric current loop greater than predetermined value, otherwise given with 0 as zero-sequence current;

(6) given to deduct described active current poor to generate active current with described active current, and given to deduct described reactive current poor to generate reactive current with reactive current, and given to deduct described zero-sequence current poor with the generation zero-sequence current with described zero-sequence current;

(7) poor to described active current by current regulator respectively, reactive current difference and zero-sequence current difference are regulated, to generate corresponding first, second, third voltage trim amount;

(8) according to described first, second, third voltage trim amount, and described tracking angle, generate the three-phase pulse width modulated switching waveform that transforms to rest frame by rotating coordinate system, be used for driving six switching devices of described rectifier.

On above-mentioned improved basis, can also save in the prior art step with the mould long correlation of voltage vector, wherein ask mould and phase-locked loop calculator can be a phase-locked loop calculator, it is output as the tracking angle, simultaneously can save adder, allow the first voltage trim amount be directly inputted to coordinate transform and PWM generator.

As seen, the given (i0 of the zero-sequence current among the present invention ^*) two kinds of probable values are arranged, when with 0 as the given (i0 of zero-sequence current ^*) when exporting, the PWM rectifier runs on the low current harmonic mode, can reduce current harmonics, improve performance index; When with electric current loop given (Iout) as the given (i0 of zero-sequence current ^*) when exporting, the PWM rectifier runs on the equal die pressing type of positive and negative busbar, can improve the ability of whole UPS band half-wave load, and reduce the pressure of equalizer circuit.Specific implementation is to carry out the logic switching by detecting the positive and negative busbar voltage condition between these two kinds of patterns.By the solution of the present invention, the rectifier of transless UPS can improve the ability of UPS band half-wave load under the prerequisite of not losing performance index, and reduces the capacity and the cost of equalizer circuit.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:

Fig. 1 is the topology diagram of a three-phase and four-line PWM rectifier among the transless UPS;

Fig. 2 is a rectifier control principle block diagram corresponding with Fig. 1 in the prior art;

Fig. 3 is the schematic diagram that available technology adopting positive and negative busbar balance of voltage device is regulated positive and negative busbar voltage;

Fig. 4 is a rectifier control principle block diagram corresponding with Fig. 1 among the present invention.

Embodiment

Be illustrated in figure 4 as the control block diagram of the rectifier among the transless UPS of the present invention.In the left-hand broken line frame is improvement part of the present invention, comprising: positive and negative busbar voltage difference adjuster 413, the given diverter switch 414 of electric current, the given switch logic 415 of electric current, the control principle of this rectifier is as follows:

(1), obtains the mould long (vd) of correspondent voltage vector and follow the tracks of angle angle by asking mould and phase-locked loop calculator 212 according to the electrical network three-phase phase voltage (Usa, Usb, Usc) that is connected with rectifier.

Be more typical way, wherein a V below ₁, V ₂, V ₃Be the intermediate variable in the computational process:

$\left[\begin{array}{c}{V}_1\\ V_2\\ V_3\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\\ \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}\end{array}\right]\left[\begin{array}{c}{U}_{\mathrm{sa}}\\ U_{\mathrm{sb}}\\ U_{\mathrm{sc}}\end{array}\right]$

$\mathrm{vd}=\sqrt{V_1^2+V_2^2+V_3^2}$

$\mathrm{angle}=\left\{\begin{array}{cc}\arccos \left(\frac{V_1}{V_d}\right)& V_2>0\\ 2\mathrm{\&pi;}-\arccos \left(\frac{V_1}{V_d}\right)& V_2<0\end{array}\right.$

(2) by first coordinate converter 211 according to described tracking angle angle, the three-phase phase current (ia, ib, ic) of three boost inductances (L1, L2, L3) carries out the conversion that static coordinate is tied to rotating coordinate system in the convection current over commutation device, draws active current (id), reactive current (iq) and the zero-sequence current (i0) of this three-phase phase current under rotating coordinate system.

Be a more typical practice below:

$\left[\begin{array}{c}\mathrm{id}\\ \mathrm{iq}\\ i0\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos \left(\mathrm{angle}\right)& \sin \left(\mathrm{angle}\right)& 0\\ \sin \left(\mathrm{angle}\right)& \cos \left(\mathrm{angle}\right)& 0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\\ \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}& \frac{1}{\sqrt{2}}\end{array}\right]\left[\begin{array}{c}\mathrm{ia}\\ \mathrm{ib}\\ \mathrm{ic}\end{array}\right]$

(3) by the given (Ud of first subtracter, 201 usefulness busbar voltages ^*) deduct Voltage Feedback (Ud), formation voltage poor (Δ U); Regulate by 202 pairs of voltage differences of voltage regulator (Δ U) again, generate the given (id of active current ^*).

(4) deduct negative busbar voltage (U-) by the 5th subtracter with the positive bus-bar voltage (U+) of rectifier, obtain positive and negative busbar voltage difference (EU), again according to described positive and negative busbar voltage difference (EU) and the given (EU of positive and negative busbar voltage difference ^*), generate corresponding electric current loop given (Iout); Positive and negative busbar voltage difference adjuster 413 wherein is controlled adjusters of the single output of a dual input, and it is input as the given (EU of positive and negative busbar voltage difference ^*, representative value is a numerical value 0) and positive and negative busbar voltage difference (EU=(U+)-(U-)), it is to the given (EU of positive and negative busbar voltage difference ^*) and after positive and negative busbar voltage difference (EU) carried out some mathematical operation, after utilizing PI (proportional integral) adjuster to carry out common proportional integral computing, the output result was electric current loop given (Iout).

(5) the given diverter switch 414 of electric current is in the electric current loop given (Iout) of positive and negative busbar voltage difference adjuster output and selection one output between 0, and the result is then as the given (i0 of zero-sequence current in output ^*).The given diverter switch of electric current 414 is concrete, and between 0 which select Iout still be, and then the output result by the given switch logic 415 of electric current decides.When selecting to be output as Iout, rectifier works in the equal die pressing type of positive and negative busbar, can improve the ability of UPS band half-wave load, and reduces the pressure of equalizer circuit; When selecting to be output as 0, rectifier works in the low current harmonic mode, can reduce current harmonics, improve performance index.

The given switch logic 415 of electric current carries out logic determines according to the information of positive and negative busbar voltage (U+, U-), is Iout or 0 with the output that determines the given diverter switch 414 of electric current.Normally judge the difference of positive and negative busbar absolute value (| EU|) whether greater than certain predefined normal value (Uset), if then the given diverter switch 414 of given switch logic 415 Control current of electric current is output as Iout, otherwise be output as 0, that is:

${\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="C20031010423600132.png"\; state="\{\{state\}\}">i</figure-callout>}0}^{*}=\left\{\begin{array}{cc}\mathrm{Iout}& |\left(U+\right)-(U-)|>\mathrm{Uset}\\ 0& |(U+)-(U-)|<=\mathrm{Uset}\end{array}\right.$

During concrete enforcement, the value of Uset will be chosen according to the electric parameter compromise of system.Generally speaking, under all common loads, during steady operation, guarantee that rectifier works in the low current harmonic mode, i.e. this moment at UPS | (U+)-(U-) |＜Uset; To guarantee that simultaneously UPS busbar voltage when all transient workings does not all surpass the rated insulation voltage value of used electrochemical capacitor.

For instance, in the product design of a certain transless UPS, positive and negative busbar voltage and (| stationary value U+|+|U-|) is 810V.The rated insulation voltage value of the used electrochemical capacitor of positive and negative busbar is 450V.When positive and negative busbar voltage difference (| (U+)-(U-) |) during greater than 90V, a voltage in the used electrochemical capacitor of positive and negative busbar must surpass the withstand voltage of 450V.In addition, in all common loads of UPS, cause during steady operation that positive and negative busbar voltage difference (| (U+)-(U-) |) fluctuation is 30V to the maximum.So theoretically, Uset can be chosen for any middle value of 30V～90V.But consider the uncertain factors such as response speed that detect deviation, system, Uset finally is chosen for 50V in this product design.

(6) according to the given (id of aforementioned active current of trying to achieve ^*) and the given (i0 of zero-sequence current ^*), and get the given (iq of the given reactive current of reactive current ^*) be 0; Then by the given (id of second subtracter, 203 usefulness active currents ^*) deduct active current (id) to generate active current poor (Δ id), by the given (iq of the 3rd subtracter 204 usefulness reactive currents ^*) deduct reactive current (iq) with generation reactive current poor (Δ iq), and by the given (i0 of the 4th subtracter 205 usefulness zero-sequence currents ^*) deduct zero-sequence current (i0) to generate zero-sequence current poor (Δ iq);

(7) regulate by 206,207,208 pairs of above-mentioned active currents of first, second, third current regulator poor (Δ id), reactive current poor (Δ iq) and zero-sequence current poor (Δ i0) respectively, to generate corresponding first, second, third voltage trim amount (V41, V42, V43);

(8) by adder 209 the first voltage trim amount (V41) and the mould of the voltage vector of trying to achieve are previously grown (vd) addition, generate the 4th voltage trim amount (V44);

(9) second, third that will try to achieve by above-mentioned steps, the 4th amount trimmed (V42, V43, V44), and tracking angle (angle), be input to coordinate transform and PWM generator 210 together, generation is transformed to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, be used for driving six switching device Q1 to Q6 of rectifier, can realize purpose of the present invention.

Be compared with the prior art as can be known, improvement of the present invention is mainly in (4), (5) two steps.

On the basis of Fig. 4, can also save and long (vd) the relevant step of the mould of voltage vector, that is to say, wherein ask mould and phase-locked loop calculator 212 can be a phase-locked loop calculator, its output is only for following the tracks of angle angle, simultaneously can save adder 209, allow the first voltage trim amount (V41) be directly inputted to coordinate transform and PWM generator 210, at this moment, will be according to described first, second, tertiary voltage amount trimmed (V41, V42, V43), and described tracking angle angle, generation transforms to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, is used for driving six switching device (Q1 of described rectifier, Q2, Q3, Q4, Q5, Q6).

In abovementioned steps, the given (EU of positive and negative busbar voltage difference ^*) be 0; Given (the U of busbar voltage ^*) be normal value; Given (the iq of reactive current ^*) be 0, Perhaps as shown in the formula:

${\mathrm{iq}}^{*}=\sqrt{3}\mathrm{\&pi;f}{\mathrm{CU}}_{\mathrm{Sa}}$

Wherein: f is the input mains frequency, and C is the appearance value of one of input filter capacitor C1, C2, C3, U _SaBe input line voltage value.

After using this programme, the index of the input harmonic current of transless UPS (＜3%) does not have variation, brings up to 55% with the ability of single-phase stable state half-wave load by 15% simultaneously.When not using this programme; during UPS output zero live wire short circuit; dc bus moment crosses and is pressed onto 480V (the 450V withstand voltage that has surpassed the dc bus electrochemical capacitor), and the relevant hardware protective circuit is moved and deadlock immediately, and the inverter section that output short-circuit is eliminated back UPS can't work on.And behind application this programme, during UPS output zero live wire short circuit, dc bus moment overvoltage is 450V, and short circuit is eliminated the back inverter section and can also be worked on.And if rely on positive and negative busbar balance of voltage device to reach as above effect fully, the balancer capacity should be increased to three times, causes that cost increases.Above-mentioned test shows that this programme is not increasing cost, does not lose under the prerequisite of index of harmonic current, utilizes the potentiality of rectifier self to greatest extent, has improved the Performance And Reliability of system.

Claims (8)

1, a kind of rectifier, its pulse width modulation controlled unit comprises:

According to the electrical network three-phase phase voltage that is connected with described rectifier (Usa, Usb, Usc), draw the phase-locked loop calculator of following the tracks of angle;

The three-phase phase current (ia, ib, ic) of three boost inductances (L1, L2, L3) carries out static coordinate and is tied to the rotating coordinate system conversion in the convection current over commutation device, to generate first coordinate converter (211) of active current (id), reactive current (iq) and zero-sequence current (i0);

With the given (Ud of busbar voltage ^*) deduct positive and negative busbar absolute value of voltage sum (| U+|+|U-|), draw first subtracter (201) of voltage difference (Δ U); Described voltage difference (Δ U) is regulated to generate the given (id of active current ^*) bus regulator (202);

With the given (id of described active current ^*) deduct active current (id) to generate second subtracter (203) of active current poor (Δ id), with the given (iq of reactive current ^*) deduct described reactive current (iq) generating the 3rd subtracter (204) of reactive current poor (Δ iq), and with the given (i0 of zero-sequence current ^*) deduct described zero-sequence current (i0) to generate the 4th subtracter (205) of zero-sequence current poor (Δ i0);

Respectively to described second, third, active current poor (Δ id), reactive current poor (Δ iq) and the zero-sequence current poor (Δ i0) of the 4th subtracter output regulate, with first, second, third current regulator (206,207,208) that generates first, second, third voltage trim amount (V41, V42, V43);

According to described first, second, third voltage trim amount (V41, V42, V43), and described tracking angle, generation transforms to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, is used for driving the coordinate transform and the PWM generator (210) of six switching devices of described rectifier (Q1, Q2, Q3, Q4, Q5, Q6);

It is characterized in that, in the pulse width modulation controlled unit of described rectifier, also comprise:

According to the given (EU of positive and negative busbar voltage difference ^*) and the actual positive and negative busbar voltage difference (EU) of rectifier, generate the positive and negative busbar voltage difference adjuster (413) of electric current loop given (Iout);

When the absolute value of described actual positive and negative busbar voltage difference (| during EU|) greater than predetermined value (Uset), with described electric current loop given (Iout) as the given (i0 of zero-sequence current ^*), otherwise with 0 as the given (i0 of zero-sequence current ^*) output to the given diverter switch of electric current (414) of described the 4th subtracter (205).

2, rectifier according to claim 1 is characterized in that, also comprises in its pulse width modulation controlled unit:

According to the electrical network three-phase phase voltage that is connected with described rectifier (Usa, Usb, Usc), draw voltage vector mould long (vd) ask the mould calculator;

The described first voltage trim amount (V41) and the mould long (vd) of described voltage vector are generated mutually the adder (209) of the 4th voltage trim amount (V44);

Described coordinate transform and PWM generator (210) according to described second, third, the 4th voltage trim amount (V42, V43, V44), and described tracking angle generates the three-phase pulse width modulated switching waveform that is transformed to rest frame by rotating coordinate system.

3, rectifier according to claim 1 and 2, it is characterized in that, also comprise in its pulse width modulation controlled unit: the positive bus-bar voltage (U+) with rectifier deducts negative busbar voltage (U-), generates described actual positive and negative busbar voltage difference (EU) and outputs to the 5th subtracter of described positive and negative busbar voltage difference adjuster (413).

4, a kind of control method of rectifier is characterized in that, controls the pulse-width modulation of rectifier by following steps:

(1) according to the electrical network three-phase phase voltage (Usa, Usb, Usc) that is connected with rectifier, obtains corresponding tracking angle;

(2) the three-phase phase current (ia, ib, ic) of three boost inductances (L1, L2, L3) carries out the conversion that static coordinate is tied to rotating coordinate system in the convection current over commutation device, draws active current (id), reactive current (iq) and the zero-sequence current (i0) of this three-phase phase current under rotating coordinate system;

(3) with the given (Ud of busbar voltage ^*) deduct positive and negative busbar absolute value of voltage sum (| U+|+|U-|), formation voltage poor (Δ U) is regulated described voltage difference (Δ U) with voltage regulator again, generates the given (id of active current ^*);

(4) the positive bus-bar voltage (U+) with rectifier deducts negative busbar voltage (U-), obtains positive and negative busbar voltage difference (EU), again according to described positive and negative busbar voltage difference (EU) and the given (EU of positive and negative busbar voltage difference ^*), generate corresponding electric current loop given (Iout);

(5) when the absolute value of described positive and negative busbar voltage difference (| during EU|) greater than predetermined value (Uset), with described electric current loop given (Iout) as the given (i0 of zero-sequence current ^*), otherwise with 0 as the given (i0 of zero-sequence current ^*);

(6) with the given (id of described active current ^*) deduct described active current (id) to generate active current poor (Δ id), with the given (iq of reactive current ^*) deduct described reactive current (iq) generating reactive current poor (Δ iq), and with the given (i0 of described zero-sequence current ^*) deduct described zero-sequence current (i0) to generate zero-sequence current poor (Δ i0);

(7) by current regulator described active current poor (Δ id), reactive current poor (Δ iq) and zero-sequence current poor (Δ i0) are regulated respectively, to generate corresponding first, second, third voltage trim amount (V41, V42, V43);

(8) according to described first, second, third voltage trim amount (V41, V42, V43), and described tracking angle, generation transforms to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, is used for driving six switching devices (Q1, Q2, Q3, Q4, Q5, Q6) of described rectifier.

5, method according to claim 4, it is characterized in that, also comprise according to the electrical network three-phase phase voltage (Usa, Usb, Usc) that is connected with described rectifier, obtain the mould long (vd) of correspondent voltage vector, with the described first voltage trim amount (V41) and long (vd) addition of the mould of described voltage vector, generate the step of the 4th voltage trim amount (V44) again;

At this moment, will according to described second, third, the 4th voltage trim amount (V42, V43, V44), and described tracking angle, generation transforms to the three-phase pulse width modulated switching waveform of rest frame by rotating coordinate system, is used for driving six switching devices (Q1, Q2, Q3, Q4, Q5, Q6) of described rectifier.

6, method according to claim 5 is characterized in that, in (4) step, to the given (EU of positive and negative busbar voltage difference ^*) and positive and negative busbar voltage difference (EU) carry out ratio or proportional integral computing, generate described electric current loop given (Iout).

7, according to each described method among the claim 4-6, it is characterized in that the given (iq of described reactive current ^*) be 0;

Perhaps be: ${\mathrm{iq}}^{*}=\sqrt{3}\mathrm{\&pi;f}{\mathrm{CU}}_{\mathrm{Sa}}$

Wherein: f is the input mains frequency, and C is the appearance value of one of input filter capacitor C1, C2, C3, U _SaBe input line voltage value.

8, according to each described method among the claim 4-6, it is characterized in that the given (EU of described positive and negative busbar voltage difference ^*) be 0.

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