JP4842179B2 - Power conversion apparatus and control method thereof - Google Patents

Description

  The present invention relates to a power converter and a method for stabilizing the power converter, and more particularly to a voltage control system for an AC electric vehicle using a power converter that converts AC to DC.

  Conventionally, as shown in FIG. 4, in a voltage control system for an AC electric vehicle, a converter control system 11 for controlling the voltage Ecf across the filter capacitor 7 to a constant control target value Ecf * is detected as a control target value Ecf *. The secondary current effective value Is is obtained through the voltage controller 61 with respect to the difference between the both-end voltage detection values Ecf obtained by the device 52. The secondary current effective value command value Is * is multiplied by the output of the sine wave generator 64 to obtain a secondary current command value is *.

  For the difference between the calculated secondary current command value is * and the secondary current detection value is detected by the secondary current detector 50, the converter voltage Ec detected by the secondary voltage detector 51 through the current controller 66 is obtained. PWM control 68 is performed as a reference, and gate pulse signal PWM_C is output to converter power converter 3.

  In converter power converter 3, converter output current iconv is output in accordance with gate pulse signal PWM_C output from PWM controller 68. Although iconov is output according to the secondary current effective value command value Is *, is * = iconv is not always satisfied due to the switching delay of the converter power converter 3 and the influence of the inductance component of the wiring. In the converter control system 11 and the converter power converter 3, the filter capacitor voltage Ecf can be changed according to the direction of the converter output current iconv and controlled to a constant voltage.

  In the prior art, when the responsiveness of the voltage controller 61 included in the converter controller 11 is reduced, the voltage Ecf across the filter capacitor can be controlled to be constant when the voltage Ecf across the filter capacitor suddenly changes due to load fluctuation or the like. It tends to be impossible. On the other hand, means for reducing the responsiveness of the voltage controller 61 may be used to reduce the harmonic component of the return current flowing in the AC power supply 1, and the responsiveness is reduced to reduce the harmonic component of the return current. Is preferably reduced. If the responsiveness is reduced suddenly, the converter control system 11 becomes unstable due to the influence of the actual model not taken into account by the converter control system 11. In particular, when the converter power converter 3 is performing a regenerative operation (when iconv <0), the influence is large and the converter control system 11 becomes unstable.

  The present invention provides a power conversion device that realizes a method of stabilizing the converter control system 11 and controlling the voltage Ecf across the filter capacitor constant even when the responsiveness of the voltage controller 61 is reduced, and a stabilization method thereof The purpose is to provide.

  When the responsiveness of the voltage controller 61 is reduced, it is difficult to control the both-end voltage Ecf to be constant when a load fluctuation or the like occurs and the filter-capacitor both-end voltage Ecf changes abruptly. Therefore, the present invention provides the compensation calculation unit 10 for the purpose of stabilizing the converter control system 11 and outputs the secondary current compensation amount Is ** from the compensation calculation unit 10. By multiplying the output secondary current compensation amount Is ** and the secondary current effective value Is calculated by the power controller 61, the converter power converter 3 that has not been considered in the converter control system 11 exists. The unstable element is compensated, the control system of the converter power converter 3 is stabilized, and the voltage Ecf across the filter capacitor can be controlled to be constant.

That is, the present invention is connected to a transformer connected to an AC power source, a winding of the transformer, a converter power converter for converting AC to DC, and connected to a DC side of the converter power converter, A DC stage circuit having a filter capacitor; an inverter power converter connected to the DC stage circuit for converting DC to AC; an AC motor connected to the inverter power converter; a voltage control unit and a current control unit; has a PWM control unit, the power converter that having a, a converter controller for controlling the voltage across the constant of the filter capacitor to the input voltage across the control target value Ecf * and the voltage across the detection value Ecf of the filter capacitor in the apparatus, the converter controller, across electric voltage minimum and the filter capacitor that is assumed in the filter capacitor Compensation calculation for obtaining the secondary current compensation amount by dividing the maximum value of the detected value Ecf, the minimum voltage value assumed by the filter capacitor, and the maximum value of the voltage control target value Ecf * across the filter capacitor. The voltage control unit generates a secondary current effective value for a difference between the both-end voltage control target value Ecf * and the both-end voltage detection value Ecf of the filter capacitor, and the current control unit This is a power conversion device that performs current control based on a difference value between a secondary current command value generated by multiplying an effective value and the secondary current compensation amount by a sine wave and a secondary current detection value .

Further, the present invention is connected to the transformer connected to the AC power source, the converter power converter connected to the winding of the transformer, and connected to the DC side of the converter power converter, a DC stage circuit having a filter capacitor, connected to the DC stage circuit, and the inverter power converter for converting direct current into alternating current, and an AC motor connected to the inverter power converter, the voltage across the above control Symbol filter capacitor a converter controller for controlling a constant voltage across the filter capacitor to input target values Ecf * and the voltage across the detection value Ecf, method of controlling a power converter that having a, the converter controller, the filter The maximum value of the minimum voltage assumed by the capacitor and the detected voltage Ecf at both ends of the filter capacitor; The maximum value and, dividing to the secondary current compensation amount of the voltage across the control target value Ecf * of the voltage minimum and the filter capacitor that is assumed in capacitor, the voltage across the control target value of the filter capacitor Ecf * and A secondary current effective value for the difference between the voltage detection values Ecf at both ends is generated, and a secondary current command value generated by multiplying a value obtained by multiplying the secondary current effective value and the secondary current compensation amount by a sine wave, and 2 It is a control method of the power converter which performs current control by the difference value of the next current detection value .

According to the present invention, the converter controller 11 is provided with the compensation calculation unit 10 to obtain the secondary current command compensation amount Is ^** and compensate the unstable element of the converter power converter 3 to stabilize the converter controller 11. It can be made. As a result, the responsiveness of the voltage controller 61 included in the converter controller 11 can be reduced, and the both-ends voltage Ecf can be controlled to be constant even when the filter-capacitor both-ends voltage Ecf changes suddenly due to load fluctuations. Furthermore, since the responsiveness can be reduced as compared with the prior art, the harmonic component of the return current flowing through the AC power supply 1 can be reduced as compared with the prior art.

The best mode for carrying out the present invention will be described.
Embodiments of a power conversion device and a stabilization method thereof according to the present invention will be described with reference to the drawings.

  Example 1 will be described. FIG. 1 is a diagram illustrating a circuit configuration of the power conversion device according to the present embodiment. The power converter for an AC train in this embodiment includes a transformer 2 connected to an AC power source 1, a converter power converter 3 connected to a winding of the transformer 2 and converting AC to DC, and converter power. Inverter power converter 4 connected to the DC side of converter 3, connected to a DC stage circuit including filter capacitor 7, for converting DC to AC, AC motor 8 connected to inverter power converter 4, speed It comprises a detector 9, a converter control system 11, an inverter control system 12, and a compensation calculation unit 10.

  AC power from the AC power source 1 that is a single-phase AC power source supplies AC power to the converter power converter 3 via the transformer 2.

  The converter power converter 3 is assumed to be configured as a full bridge type composed of two phases of a U phase and a V phase. The converter power converter 3 includes two semiconductor switches, a P-side semiconductor switch 31P and an N-side semiconductor switch 31N. The P-side semiconductor switch 31P includes a P-side terminal of the transformer 2 and a P-side terminal of the filter capacitor 7. The N-side semiconductor switch 31N is connected to the N-side terminal of the transformer 2 and the N-side terminal of the filter capacitor 7. As in the converter U phase, in the converter V phase, the P-side semiconductor switch 32P connects the P-side terminal of the transformer 2 and the P-side terminal of the filter capacitor 7, and the N-side semiconductor switch 32N is connected to the transformer 2 The N side terminal and the N side terminal of the filter capacitor 7 are connected.

  Converter power converter 3 converts the AC power supplied from transformer 2 into DC power by controlling the conduction state of semiconductor switches 31P to 32N. The P-side terminal of converter power converter 3 is connected to the P-side terminal of filter capacitor 7 and the P-side terminal of inverter power converter 4. The N-side terminal of the converter power converter 3 is connected to the N-side terminal of the filter capacitor 7 and the N-side terminal of the inverter power converter 4, and the DC power supplied from the converter power converter 3 is smoothed by the filter capacitor 7. And supplied to the inverter power converter 4.

  Converter output current iconv outputted from converter power converter 3 is represented by the product of secondary current detection value is and modulation factor Vc.

  The inverter power converter 4 is a three-phase AC converter composed of three phases of U, V, and W phases. The U phase of the inverter power converter 4 includes two semiconductor switches, a P-side semiconductor switch 41P and an N-side semiconductor switch 41N. The P-side semiconductor switch 41P is connected to the P-side terminal of the filter capacitor 7 and the U-phase terminal of the AC motor 8. The N-side semiconductor switch 41N is connected to the N-side terminal of the filter capacitor 7 and the U-phase terminal of the AC motor 8. The V phase of the inverter power converter 4 includes two semiconductor switches, a P-side semiconductor switch 42P and an N-side semiconductor switch 42N. The P-side semiconductor switch 42P is connected to the P-side terminal of the filter capacitor 7 and the V-phase terminal of the AC motor 8, and the N-side semiconductor switch 42N is connected to the N-side terminal of the filter capacitor 7 and the V-phase terminal of the AC motor 8. The W phase of the inverter power converter 4 is composed of two semiconductor switches, a P-side semiconductor switch 43P and an N-side semiconductor switch 43N. The P-side semiconductor switch 43P is connected to the P-side terminal of the filter capacitor 7 and the W-phase terminal of the AC motor 8, and the N-side semiconductor switch 43N is connected to the N-side terminal of the filter capacitor 7 and the W-phase terminal of the AC motor 8.

  The inverter power converter 4 converts the DC power supplied from the converter power converter 3 into arbitrary AC power and drives the AC motor 8 by controlling the conduction state of the semiconductor switches 41P to 43N.

  The AC motor 8 is a motor that drives an AC electric vehicle. The pulse generator 9 detects the rotational speed of the AC motor and outputs a speed signal Fr.

  Next, the configuration of the converter control system 11 that generates a gate pulse signal that controls the conduction state of the semiconductor switches 31P to 32N of the converter power converter 3 according to the first embodiment will be described. The converter control system 11 includes a differencer (1) 60, a voltage control unit 61, a multiplier (1) 62, a multiplier (2) 63, a sine wave generator 64, a differencer (2) 65, , Current controller 66, subtractor (3) 67, and PWM controller 68.

  The converter control system 11 controls the voltage Ecf across the filter capacitor 7 to be constant. The secondary current effective value Is is obtained through the voltage controller 61 with respect to the difference between the control target value Ecf * and the both-ends voltage detection value Ecf obtained by the detector 52.

  FIG. 2 is a diagram illustrating the compensation calculation unit 10 according to the first embodiment. The compensation calculation unit 10 includes a divider (3) 10a. A secondary current compensation amount Is ** is obtained from the filter capacitor both-end voltage control target value Ecf and the detected value Ecf *, and is output to the converter control system 11.

  The secondary current compensation value Is ** and the secondary current effective value Is are multiplied by the multiplier (1) 62 to obtain the secondary current effective value command value Is *.

  The secondary current effective value command value Is * is multiplied by the output of the sine wave generator 64 to obtain a secondary current command value is *. The current controller 66 performs current control on the difference between the calculated secondary current command value is * and the detected secondary current value is detected by the secondary current detector 50. The subtractor (3) 67 subtracts the converter voltage Ec detected by the secondary voltage detector 51 from the output operation amount of the previous current controller 66, and outputs a converter U-phase voltage command Vu and a converter V-phase voltage command Vv. .

  PWM control 68 is performed, converter U-phase voltage command Vu and converter V-phase voltage command Vv are input, PWM calculation is performed with reference to filter capacitor voltage Ecf detected by filter capacitor both-end voltage detector 52, and gate pulse signal PWM_C Is output.

  In converter power converter 3, according to gate pulse signal PWM_C output from PWM controller 68, semiconductor switches 31P to 32N are turned on and off to output converter output current iconv. Although iconov is output according to the secondary current effective value command value Is *, Is * = iconv is not necessarily satisfied due to the switching delay of the converter power converter 3 and the influence of the inductance component of the wiring. In the converter control system 11 and the converter power converter 3, the filter capacitor voltage Ecf is changed according to the direction of the converter output current iconv and controlled to a constant voltage.

  The inverter control system 12 obtains a voltage command from the speed signal Fr and the motor current Im, performs a PWM calculation with the filter capacitor voltage Ecf as a reference, and outputs a gate pulse signal PWM_I.

  A second embodiment will be described. The power conversion device of the present embodiment is the same as that of the first embodiment, but the compensation calculation unit 10 is different. In the second embodiment, the compensation calculation unit 10 shown in FIG. 3 is provided to calculate the secondary current compensation amount Is **. The compensation calculation unit 10 inputs the filter capacitor both-end voltage detection value Ecf and the filter capacitor voltage minimum value Ecf_min to the maximum value calculator (1) 10b, and sets the filter capacitor both-end voltage control target value Ecf * and the filter capacitor voltage minimum value Ecf_min. The value is inputted to the maximum value calculator (2) 10c, and the value calculated by each of the maximum value calculators 10b and 10c is divided by the divider (1) 10a to obtain the secondary current compensation amount Is **. As the filter capacitor voltage minimum value Ecf_min, a lower limit value assumed at the time of setting is used as the voltage detection value across the filter capacitor. Thereby, even if 0 (zero) V is detected as the detected voltage Ecf across the filter capacitor, runaway due to division can be prevented.

Explanatory drawing of the circuit structure of the power converter device of Example 1,2. FIG. 3 is an explanatory diagram of a compensation calculation unit in the first embodiment. Explanatory drawing of the compensation calculating part in Example 2. FIG. Explanatory drawing of the circuit structure of the conventional power converter device.

Explanation of symbols

1 AC Power Supply 2 Transformer 3 Converter Power Converter 4 Inverter Power Converter 7 Filter Capacitor 8 AC Motor 9 Pulse Generator (Speed Detector)
DESCRIPTION OF SYMBOLS 10 Compensation calculating part 11 Converter control system 12 Inverter control system 31P Converter U phase P side semiconductor switch 31N Converter U phase N side semiconductor switch 32P Converter V phase P side semiconductor switch 32N Converter V phase N side semiconductor switch 41P Inverter U phase P side Semiconductor switch 41N Inverter U phase N side semiconductor switch 42P Inverter V phase P side semiconductor switch 42N Inverter V phase N side semiconductor switch 43P Inverter W phase P side semiconductor switch 43N Inverter W phase N side semiconductor switch 50 Secondary current detector 51 2 Secondary voltage detector 52 Voltage detector across filter capacitor 53 Motor current detector 60 Differential 1
61 Voltage Control Unit 62 Multiplier 1
63 Multiplier 2
64 sine wave generator 65 subtractor 2
66 Current control unit 67 Difference unit 3
68 PWM control unit Ep Primary voltage Ec Converter voltage Ecf Detected value Ecf across filter capacitor Ecf ^* Voltage control target value Vc across filter capacitor Modulation factor Is Secondary current effective value Is ^* Secondary current effective value command Is ^** Secondary current Compensation amount iconv Converter output current is Secondary current detection value is ^* Secondary current command value im Induction machine load current Fr Rotor rotation frequency detection value PMW_C Converter gate pulse signal PWM_I Inverter gate pulse signal

Claims (2)

A transformer connected to an AC power source;
A converter power converter connected to the winding of the transformer and converting AC to DC;
A DC stage circuit connected to the DC side of the converter power converter and having a filter capacitor;
An inverter power converter connected to the DC stage circuit for converting DC to AC;
An AC motor connected to the inverter power converter;
It has a voltage controller and the current control unit and a PWM control unit, the converter controller for controlling a constant voltage across the filter capacitor to the input voltage across the control target value Ecf * and the voltage across the detection value Ecf of the filter capacitor If, in the power conversion apparatus that have a,
The converter controller controls the maximum value of the minimum voltage assumed in the filter capacitor and the detected voltage Ecf across the filter capacitor, the minimum voltage assumed in the filter capacitor, and the voltage control across the filter capacitor. A compensation calculation unit that calculates a secondary current compensation amount by dividing the maximum value of the target value Ecf * with the target value Ecf *;
The voltage control unit generates a secondary current effective value for a difference between the both-end voltage control target value Ecf * of the filter capacitor and the both-end voltage detection value Ecf ,
The current control unit performs current control based on a difference value between a secondary current command value generated by multiplying the secondary current effective value and the secondary current compensation amount by a sine wave and a secondary current detection value. The power converter characterized by performing . A transformer connected to an AC power source;
A converter power converter connected to the winding of the transformer and converting AC to DC;
A DC stage circuit connected to the DC side of the converter power converter and having a filter capacitor;
An inverter power converter connected to the DC stage circuit for converting DC to AC;
An AC motor connected to the inverter power converter;
A converter controller for controlling a constant voltage across the filter capacitor to the input voltage across the control target value Ecf * and the voltage across the detection value Ecf above SL filter capacitor, the control method of the power converter that having a,
The converter controller controls the maximum value of the minimum voltage assumed in the filter capacitor and the detected voltage Ecf across the filter capacitor, the minimum voltage assumed in the filter capacitor, and the voltage control across the filter capacitor. Divide the maximum value of the target value Ecf * and obtain the secondary current compensation amount,
A secondary current effective value for the difference between the both-end voltage control target value Ecf * of the filter capacitor and the both-end voltage detection value Ecf is generated;
Current control is performed using a difference value between a secondary current command value generated by multiplying a value obtained by multiplying the secondary current effective value and the secondary current compensation amount by a sine wave and a secondary current detection value. Control method of power converter.

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