CN101420181A - Three phase four bridge arm matrix type converter having excitation function - Google Patents

Abstract

The invention discloses a three-phase four-bridge arm matrix typed converter with an excitation function, belonging to the field of power converter. The structure of the converter mainly comprises a hybrid excited synchronous motor, a three-phase four-bridge arm matrix-typed converter and a clamp protection circuit. The converter uses the fourth bridge arm output terminal of the three-phase four-bridge arm matrix-typed converter to be connected with the input terminal of the excitation winding of the hybrid excited synchronous motor, the output terminal of which is connected in parallel with the fixed end of a bidirectional selection switch between the clamp protection circuit buses so as to form the excitation circuit, thus realizing the integral design of the power converter and the excitation circuit. In the invention, the converter not only has the advantages of traditional three-phase AC-AC matrix converter, but also realizes the motor excitation control, thereby reducing the excitation loss of the system and improving the efficiency of the system at the same time.

Description

Three phase four bridge arm matrix type converter with excitation function

Technical field

The present invention relates to a kind of matrix converter, particularly a kind of three phase four bridge arm matrix type converter with excitation function belongs to the power inverter field.

Background technology

Alternating current machine is a motor of realizing electric energy and mechanical energy conversion.The used electric energy of industrial or agricultural and daily life generally is synchronous generator and supplies with, and during the synchronous machine generator operation, the motor output voltage is relevant with motor-field, by regulating excitation field, can realize the control to the motor output voltage.In the electric excitation synchronous motor, except that armature winding, also with a cover excitation winding.Regulate the exciting current that flows through in the excitation winding and can regulate excitation field easily, thereby realize control the motor output voltage.Such motor excitation is controlled, has good regulating characteristics, and demagnetization is simple, has improved reliability of system operation.In addition, electric excitation combined with permanent magnet excitation constitutes the new type composite excitation synchronous machine, has controlled advantage of electro-magnetic motor excitation and the high efficiency advantage of magneto concurrently, has wide application and good prospects for application.

Synchronous machine output electric energy need offer specific load usually after the conversion of overfrequency and voltage.The alternating electromotive force converter can be divided into AC-DC-AC type and two kinds of forms of ac-ac type usually.AC-DC-AC type electric power converter plant has obtained extensive use because of it has good frequency conversion performance.But it exists, and the input side power factor (PF) is low, serious to harmonic pollution in electric power net, energy is difficult to realize problems such as two-way flow.Matrix converter be a kind of can realize importing mutually from m convert directly to the power-converting device that n exports mutually, can realize multiple conversion such as AC-AC, AC-DC.Compare with traditional AC-DC-AC type power-converting device, but matrix converter has that input power factor height, input current waveform are good, the energy two-way flow, can realize advantages such as four quadrant running, no intermediate dc energy storage link, circuit structure compactness, volume be little.Therefore, matrix converter is one of preferred version of alternating current machine realization power converter.

The ac synchronous motor excitation mode has multiple choices, as self-excitation, separate excitation etc.At present, during most of ac synchronous motor Control System Design excitation winding regulating circuit and main power conversion circuit are separated independent design, so not only increase volume, the weight of system, increased the complexity and the cost of system simultaneously, reduced system reliability.

Summary of the invention

The present invention is a kind of in conjunction with power inverter and the incorporate circuit of field circuit and propose a kind of three phase four bridge arm matrix type converter with excitation function in order to design.

A kind of three phase four bridge arm matrix type converter with excitation function; comprise hybrid exciting synchronous motor; three phase four bridge arm matrix type converter and clamping protection circuit; wherein: the three-phase output end of hybrid exciting synchronous motor connects the three-phase input end of three phase four bridge arm matrix type converter and the three-phase input end of clamping protection circuit respectively; first to the 3rd brachium pontis output of three phase four bridge arm matrix type converter had both connected the three-phase output end of clamping protection circuit respectively; connect three-phase electricity network or threephase load again respectively; the 4th brachium pontis output of three phase four bridge arm matrix type converter connects the input of the excitation winding of hybrid exciting synchronous motor, and the output of the excitation winding of hybrid exciting synchronous motor connects the stiff end that is connected in parallel on the two-way gating switch between clamping protection circuit bus.

The present invention is that the three-phase that utilizes three phase four bridge arm matrix type converter to export in four brachium pontis is realized three-phase input AC electricity friendship-alternating current force transformation, utilize the 4th brachium pontis to realize the adjusting of motor excitation winding exciting current, the advantage that not only has the traditional three-phase AC-AC matrix converter can realize motor excitation control simultaneously.Power conversion circuit and field circuit are integrated to make system design obtain simplifying, and compact conformation helps the system integration.Have only a power switch pipe and a power diode to be in conducting state during energized circuit work, can reduce the excitation loss of system, improve system effectiveness.

Description of drawings

Fig. 1 is a circuit structure topological diagram of the present invention, the number in the figure title: 1, hybrid exciting synchronous motor, 2, three phase four bridge arm matrix type converter, 3, the clamping protection circuit.

Fig. 2 is that gating switch of the present invention connects clamping protection circuit anode dc bus energized circuit modulation period working state figure: (a) switch S _AfEnergized circuit working state figure when opening; (b) switch S _BfEnergized circuit working state figure when opening; (c) switch S _CfEnergized circuit working state figure when opening.

Fig. 3 is that gating switch of the present invention connects clamping protection circuit negative polarity dc bus energized circuit modulation period working state figure: (a) switch S _AfEnergized circuit working state figure when opening; (b) switch S _BfEnergized circuit working state figure when opening; (c) switch S _CfEnergized circuit working state figure when opening.

Embodiment

As shown in Figure 1; a kind of three phase four bridge arm matrix type converter with excitation function; comprise hybrid exciting synchronous motor 1; three phase four bridge arm matrix type converter 2 and clamping protection circuit 3; wherein: the three-phase output end of hybrid exciting synchronous motor 1 connects the three-phase input end of three phase four bridge arm matrix type converter 2 and the three-phase input end of clamping protection circuit 3 respectively; first to the 3rd brachium pontis output of three phase four bridge arm matrix type converter 2 had both connected the three-phase output end of clamping protection circuit 3 respectively; connect three-phase electricity network or threephase load again respectively; the 4th brachium pontis output of three phase four bridge arm matrix type converter 2 connects the input of the excitation winding of hybrid exciting synchronous motor 1, and the output of the excitation winding of hybrid exciting synchronous motor 1 connects the stiff end that is connected in parallel on the two-way gating switch S between clamping protection circuit 3 buses.

Three phase four bridge arm matrix type converter 2 topologys are made of 12 bidirectional switchs among the present invention, and each bidirectional switch all has the function of two-way admittance and two-way shutoff.12 bidirectional switchs become 3 * 4 matrix forms to arrange.Each input all has mutually with each output and only is connected with a bidirectional switch.Adopt suitable modulator approach, adopt pulse-width modulation just can obtain desired output voltage 12 bidirectional switchs.Three phase four bridge arm matrix type converter 2 input/output relations can be expressed as:

$\left[\begin{array}{c}{U}_A\\ U_B\\ U_C\\ U_f\end{array}\right]=\left[\begin{array}{ccc}{S}_{\mathrm{aA}}& S_{\mathrm{bA}}& S_{\mathrm{cA}}\\ S_{\mathrm{aB}}& S_{\mathrm{bB}}& S_{\mathrm{cB}}\\ S_{\mathrm{aC}}& S_{\mathrm{bC}}& S_{\mathrm{cC}}\\ S_{\mathrm{af}}& S_{\mathrm{bf}}& S_{\mathrm{cf}}\end{array}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right],$

Wherein, the three-phase output voltage U of three phase four bridge arm matrix type converter 2 _A, U _B, U _CBy control bidirectional switch S _JkState (j ∈ a, and b, c}, k ∈ A, B, C}), by the input three-phase voltage U _a, U _b, U _cSynthetic obtaining, suc as formula:

$\left[\begin{array}{c}{U}_A\\ U_B\\ U_C\end{array}\right]=\left[\begin{array}{ccc}{S}_{\mathrm{aA}}& S_{\mathrm{bA}}& S_{\mathrm{cA}}\\ S_{\mathrm{aB}}& S_{\mathrm{bB}}& S_{\mathrm{cB}}\\ S_{\mathrm{aC}}& S_{\mathrm{bC}}& S_{\mathrm{cC}}\end{array}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right],$

Concrete control mode is analogous to conventional three-phase-three-phase matrix converter.

For the protection bidirectional switch is not damaged, this converter need be provided with clamping protection circuit 3 and suppress the high pressure spike, and clamping protection circuit 3 is made up of clamping capacitance, bleeder resistance and two groups of rectifier bridges.Clamping capacitance plays the voltage clamping action, suppresses due to voltage spikes, protection three-phase AC-AC formula matrix converter main circuit bidirectional switch.Under the normal condition, maximum corresponding two diode current flows of input line voltage amplitude in the input side diode rectifier bridge, the outlet side diode all ends.

Among the present invention; utilize the 4th brachium pontis output of three phase four bridge arm matrix type converter 2 to connect the input of the excitation winding of hybrid exciting synchronous motor 1; what the output of the excitation winding of hybrid exciting synchronous motor 1 connected the two-way gating switch S that is connected in parallel between clamping protection circuit 3 buses fixedly brings in the formation energized circuit, and two-way gating switch S plays a part the exciting current direction is controlled.According to two-way gating switch S and clamping protection circuit 3 ways of connecting, energized circuit divides two kinds of working conditions:

(1) as shown in Figure 2; two-way gating switch S is connected with clamping protection circuit 3 bus positive ends; the diode current flow that with input voltage maximal phase be connected in the diode because of the connection of clamping protection circuit 3 input side rectifier bridge common cathodes this moment; one end of excitation winding links to each other control switch S with amplitude maximal phase in the input side three-phase voltage _Af, S _Bf, S _CfOpen shutoff, i.e. the voltage at may command excitation winding two ends.For avoiding the input side short circuit occurring and open circuit conditions appears in energized circuit, any moment bidirectional switch S _Af, S _Bf, S _CfIn have and have only one to be in conducting state.With a phase voltage amplitude U in the three-phase input voltage _aWhen maximum is the operation principle that example is introduced energized circuit, and the diode of corresponding conducting is D in the clamping protection circuit 3 at this moment ₁, work as S _AfWhen opening, the energized circuit operation mode is shown in Fig. 2 (a), and the voltage at excitation winding two ends is 0; Work as S _BfWhen opening, the energized circuit operation mode is shown in Fig. 2 (b), and the voltage at excitation winding two ends is U _AbWork as S _CfWhen opening, the energized circuit operation mode is shown in Fig. 2 (c), and the voltage at excitation winding two ends is U _AcTo S _Af, S _Bf, S _CfAdopt pulse-width modulation, the excitation winding voltage U _fBy the input three-phase voltage U _a, U _b, U _cSynthetic obtaining, suc as formula:

$\left[U_f\right]=\left[S_{\mathrm{af}}{S}_{\mathrm{bf}}{S}_{\mathrm{cf}}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right],$

Set S in the modulation period _Af, S _Bf, S _CfThe conducting duty ratio is respectively d ₀, d ₁, d ₂, U then _f=d ₁* U _Ab+ d ₂* U _AcBy setting the duty ratio of corresponding switching tube, just can realize adjusting, and then realize adjusting exciting current to excitation winding voltage.The working condition of energized circuit similarly under other input voltage situation.

(2) as shown in Figure 3; two-way gating switch S links to each other with clamping protection circuit 3 bus negative polarity ends; be total to the diode current flow that is connected with the input voltage minimum in the diode of anode connection this moment because of clamping protection circuit 3 input side rectifier bridges; the voltage minimum links to each other in one end of excitation winding and the input side three-phase voltage, same control switch S _Af, S _Bf, S _CfOpen shutoff, i.e. the voltage at may command excitation winding two ends.With a phase voltage U in the three-phase input voltage _aThe amplitude minimum is the operation principle that example is introduced energized circuit, and the diode of corresponding conducting is D in this clamping protection circuit ₂, work as S _AfWhen opening, the energized circuit operation mode is shown in Fig. 3 (a), and the voltage at excitation winding two ends is 0; Work as S _BfWhen opening, the energized circuit operation mode is shown in Fig. 3 (b), and the voltage at excitation winding two ends is U _AbWork as S _CfWhen opening, the energized circuit operation mode is shown in Fig. 3 (c), and the voltage at excitation winding two ends is U _AcEqually, to S _Af, S _Bf, S _CfAdopt pulse-width modulation, set S in the modulation period _Af, S _Bf, S _CfThe conducting duty ratio is respectively d ₀', d ₁', d ₂', the voltage at excitation winding two ends, then synthetic back is U _f=d ₁' * U _Ab+ d ₂' * U _Ac, because U _a＜U _b, U _a＜U _c, so U is arranged _Ab＜0, U _Ac＜0, U then _f＜0.Exciting voltage is for bearing the exciting current reverse flow.

In the practical application, the connected mode of two-way gating switch S has determined the exciting current direction, and effective conducting duty ratio of exciting bridge arm switch pipe has determined the size of excitation winding electric current, and this control mode is succinctly practical, can realize the two-way controlled excitation of motor.

Claims (1)

1; a kind of three phase four bridge arm matrix type converter with excitation function; comprise hybrid exciting synchronous motor (1); three phase four bridge arm matrix type converter (2) and clamping protection circuit (3); wherein: the three-phase output end of hybrid exciting synchronous motor (1) connects the three-phase input end of three phase four bridge arm matrix type converter (2) and the three-phase input end of clamping protection circuit (3) respectively; first to the 3rd brachium pontis output of three phase four bridge arm matrix type converter (2) had both connected the three-phase output end of clamping protection circuit (3) respectively; connect three-phase electricity network or threephase load again respectively; it is characterized in that: the 4th brachium pontis output of three phase four bridge arm matrix type converter (2) connects the input of the excitation winding of hybrid exciting synchronous motor (1), and the output of the excitation winding of hybrid exciting synchronous motor (1) connects the stiff end that is connected in parallel on the two-way gating switch (S) between clamping protection circuit (3) bus.

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