JP2004015897A - PWM rectifier output control method and output control device - Google Patents

Abstract

An object of the present invention is to suppress the resonance generated on the output side of a PWM rectifier, and to control the DC output voltage of the PWM rectifier with high accuracy in a steady state.
A current change rate calculator calculates a temporal change rate of a DC output current detected by a PWM rectifier, and generates a correction signal proportional to the current change rate. The multiplier 21 multiplies the correction signal by a correction gain K to obtain a droop amount Edccmp. The subtracter 22 subtracts the droop amount Edccmp from the DC output voltage command value Edc1 of the PWM rectifier to obtain a correction command value Edc2. The subtracter 23 calculates a deviation ΔE between the correction command value Edc2 and the DC output voltage Edc, and the DC voltage regulator 24 generates an effective current command Id according to the deviation ΔE. The switching signal generation circuit 25 generates a signal for turning on and off the transistor of the PWM rectifier to make the deviation ΔE zero based on the effective current command Id.
[Selection] Figure 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an output control device of a power conversion device (converter) that obtains DC power by converting AC to DC, and more particularly to an output control method of a PWM rectifier including a semiconductor switching element in a forward conversion circuit, and an output control device thereof. It is about.
[0002]
[Prior art]
As an output control device of this kind of PWM rectifier, for example, the one shown in FIG. 4 is known.
In this output control device, a DC output current Idc of a PWM rectifier (not shown) as shown in FIG. 5A is input to the multiplier 1, and the DC output current Idc is detected by a current sensor (not shown). It is a thing. The multiplier 1 multiplies the DC output current Idc by a correction gain K, and outputs the result to the subtractor 2 as a droop amount Edccmp of a command value (target value) Edc1 of the DC output voltage of the PWM rectifier.
[0003]
The subtracter 2 corrects the command value Edc1 by subtracting the droop amount Edccmp from the command value Edc1 of the DC output voltage, and outputs the corrected command value Edc2 to the subtractor 3 (FIG. 5B )reference). The subtracter 3 obtains a deviation ΔE between the corrected command value Edc2 of the corrected DC output voltage and the DC output voltage Edc of the PWM rectifier, and outputs the obtained difference ΔE to the DC voltage regulator 4.
[0004]
The DC voltage regulator 4 generates an effective current command Id according to the deviation ΔE, and outputs the generated effective current command Id to the switching signal generation circuit 5. The switching signal generation circuit 5 generates a switching signal for turning on / off a transistor constituting a PWM rectifier to make the above-mentioned deviation ΔE zero based on the effective current command Id.
[0005]
Since this switching signal is supplied to the transistor constituting the PWM rectifier, the transistor is on / off controlled. As a result, the DC output voltage Edc of the PWM rectifier is controlled to become the correction command value Edc2.
For this reason, if a reactor and a capacitor are present in the load connected to the PWM rectifier, resonance occurs between the load and the built-in capacitor on the output side of the PWM rectifier. it can.
[0006]
[Problems to be solved by the invention]
However, in a conventional output control device for a PWM rectifier, as shown in FIG. 4, a DC output current Idc is multiplied by a correction gain K, thereby correcting a DC output voltage command value Edc1 to correct a DC output voltage correction command. The value Edc2 is determined.
For this reason, as shown in FIG. 5, in the steady state in which the above-mentioned resonance does not occur, a deviation ΔEdc remains between the DC output voltage command value Edc1 and its correction command value Edc2. As a result, in the conventional PWM rectifier output control device, when resonance occurs, the resonance can be suppressed. However, since the above-mentioned deviation ΔEdc remains, the DC output voltage control of the PWM rectifier can be controlled with high accuracy. There was a disadvantage that it could not be performed.
[0007]
In view of the above, an object of the present invention is to suppress the resonance generated on the output side of the PWM rectifier, and to precisely control the DC output voltage of the PWM rectifier in a steady state where no resonance occurs. An object of the present invention is to provide an output control method of a PWM rectifier and an output control device for controlling the output.
[0008]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object of the present invention, each of the inventions according to claims 1 and 2 is configured as follows.
That is, the invention according to claim 1 is an output control method for a PWM rectifier including a semiconductor switching element that controls a DC output voltage by switching control while generating DC power by converting AC to DC. A temporal change in the DC output current output from the PWM rectifier is detected, and when there is a temporal change, a correction value corresponding to the degree of the change is obtained, and the DC output output from the PWM rectifier is detected. A target value of the voltage is corrected by the obtained correction value, a deviation between the corrected target value and the DC output voltage of the PWM rectifier is obtained, and the semiconductor switching element is set so that the obtained deviation becomes zero. Is performed.
[0009]
The invention according to claim 2 is an output control device for a PWM rectifier that includes a semiconductor switching element that converts DC to DC to generate DC power and controls a DC output voltage by switching control, wherein the PWM rectifier Change rate calculating means for calculating a temporal change in the DC output current of the PWM rectifier, generating and outputting a correction signal having a correction value corresponding to the degree of the temporal change, and the PWM rectifier. A target value correcting means for correcting a target value of the DC output voltage with a correction signal of the change rate calculating means, and a deviation calculation for obtaining a deviation between the target value corrected by the target value correcting means and the DC output voltage of the PWM rectifier. Means for generating a signal for switching the semiconductor switching element such that the deviation becomes zero in accordance with the deviation obtained by the deviation calculating means. It is characterized in that it comprises a signal generating means.
[0010]
As described above, in the present invention, the DC output current of the PWM rectifier is detected, the temporal change is obtained from the detected DC output current, and when there is a temporal change, a correction value corresponding to the change is obtained. The target value (command value) of the DC output voltage of the PWM rectifier is corrected by the obtained correction value.
For this reason, the target value of the DC output voltage of the PWM rectifier is corrected only during a period in which the DC output current detected by the PWM rectifier is changing.
[0011]
As a result, according to the present invention, it is possible to suppress the resonance that occurs when the load of the PWM rectifier is connected, and to control the DC output voltage of the PWM rectifier to the target value in a steady state where no resonance occurs. The DC output voltage can be controlled with higher accuracy.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The output control device of the PWM rectifier according to the present invention is configured as shown in FIG. 2. This output control device controls the output of the PWM rectifier as shown in FIG. 1, for example. The configuration of the target PWM rectifier will be described.
[0013]
The PWM rectifier performs, for example, three-phase full-wave rectification, and includes a transformer 11, an AC-DC converter (inverter) 12, a smoothing capacitor C1, and output terminals 13 and 14, as shown in FIG. At least, a load 15 is connected to the output terminals 13 and 14 thereof.
The AC-DC converter 12 is connected to a three-phase AC power supply 16 via a transformer 11 or the like, and converts (rectifies) three-phase AC into DC. For this purpose, the AC-DC converter 12 includes rectifier diodes D1 to D6. ing. Transistors Q1 to Q6 as semiconductor switching elements are connected in anti-parallel to both ends of the rectifier diodes D1 to D6.
[0014]
The transistors Q1 to Q6 are turned on / off by a switching signal from the output control device 17 shown in FIG. 2, so that the DC output voltage Edc generated at the output terminals 13 and 14 is controlled to a constant value as described later. Has become.
A smoothing capacitor C1 is connected to the DC output side of the AC-DC converter 12. The load 15 connected to the output terminals 13 and 14 includes a reactor L1 and a capacitor C2 in addition to the resistor R.
[0015]
Next, an embodiment of an output control device for a PWM rectifier according to the present invention will be described with reference to FIG.
As shown in FIG. 2, the output control device 17 includes a current change rate calculator 20, a multiplier 21, a subtractor 22, a subtractor 23, a DC voltage regulator (AVR) 24, and a switching signal generator. And a circuit 25.
[0016]
Here, the change rate calculating means of the present invention is provided in the current change rate calculator 20, the target value correcting means is provided in the subtractor 22, the deviation calculating means is provided in the subtractor 23, the switching signal generating means is provided in the switching signal generating circuit 25 and the like. , Respectively.
The current change rate calculator 20 is configured to receive a DC output current Idc detected by a current sensor (not shown) for detecting the DC output current Idc of the PWM rectifier shown in FIG. The current change rate calculator 20 calculates the temporal change rate of the DC output current Idc, generates a correction signal proportional to the current change rate, and outputs the correction signal to the multiplier 21.
[0017]
The multiplier 21 multiplies the correction signal by the correction gain K, and outputs the result to the subtractor 22 as a droop amount Edccmp of the command value (target value) Edc1 of the DC output voltage of the PWM rectifier.
The subtracter 22 corrects the command value Edc1 by subtracting the droop amount Edccmp from the command value Edc1 of the DC output voltage, and outputs the corrected command value Edc2 to the subtractor 23. .
[0018]
The subtractor 23 calculates a deviation ΔE between the corrected DC output voltage correction command value Edc2 and the DC output voltage Edc from the PWM rectifier, and outputs the calculated deviation ΔE to the DC voltage regulator 24. ing.
The DC voltage regulator 24 generates an effective current command Id according to the deviation ΔE, and outputs the generated effective current command Id to the switching signal generation circuit 25.
[0019]
The switching signal generation circuit 25 generates a switching signal (PWM signal) for turning on and off the transistors Q1 to Q6 constituting the PWM rectifier in order to make the deviation ΔE zero based on the effective current command Id. The power is supplied to the input side of each of the transistors Q1 to Q6 in FIG.
Next, an example of output control of the PWM rectifier by the output control device 17 having such a configuration will be described with reference to FIGS.
[0020]
A current sensor (not shown) detects the DC output current Idc of the PWM rectifier as shown in FIG. 3A, for example, and this is input to the current change rate calculator 20. The current change rate calculator 20 calculates a temporal change rate of the detected DC output current Idc, generates a correction signal (compensation signal) proportional to the current change rate, and generates the correction signal. Output to the multiplier 21.
[0021]
Here, the correction signal is generated by calculating the temporal change rate of the DC output current Idc as described above and in proportion to the current change rate. However, the correction signal only needs to be a signal that determines the temporal change, has a correction value according to the change when the time changes, and is not output when there is no change.
The correction signal is multiplied by the correction gain K in the multiplier 21 and output to the subtractor 2 as a droop amount Edccmp of the command value Edc1 of the DC output voltage of the PWM rectifier.
[0022]
The command value Edc1 of the DC output voltage of the PWM rectifier is input to the subtractor 22, and the command value Edc1 is subtracted by the droop amount Edccmp from the multiplier 21 to correct the command value Edc1, This corrected command value is output to the subtractor 23 as Edc2. FIG. 3B shows an example of the correction command value Edc2.
[0023]
Here, when the DC output current Idc does not change, no correction signal is output from the current rate-of-change calculator 20, and as shown in FIG. 3B, the command value Edc1 of the DC output voltage is not corrected, and Edc2 = Edc1.
The subtracter 23 calculates a deviation ΔE between the corrected DC output voltage correction command value Edc2 and the DC output voltage Edc of the PWM rectifier, and the obtained deviation ΔE is output to the DC voltage regulator 24. .
[0024]
The DC voltage regulator 24 generates a predetermined effective current command Id according to the deviation ΔE, and the generated effective current command Id is output to the switching signal generation circuit 25.
The switching signal generation circuit 25 generates, based on the effective current command Id, a switching signal for turning on and off a transistor constituting the PWM rectifier to reduce the above-mentioned deviation ΔE to zero. , Respectively.
[0025]
As a result, the on / off control of the transistor is performed, and the output DC voltage of the PWM rectifier is controlled to be the correction command value Edc2.
As described above, in this embodiment, the DC output current Idc of the PWM rectifier is detected, the temporal change rate is obtained from the detected DC output current Idc, and the correction amount proportional to the current change rate is obtained. The correction value is subtracted from the command value Edc1 of the DC output voltage of the PWM rectifier to correct the command value Edc1.
[0026]
For this reason, as shown in FIG. 3, the command value Edc1 of the DC output voltage of the PWM rectifier is corrected only during a period in which the DC output current Idc detected by the PWM rectifier is changing.
Therefore, in a steady state in which the DC output current Idc does not change, as shown in FIG. 3, the correction command value Edc2 output from the subtractor 22 is not corrected and remains at the command value Edc1, and becomes equal to the command value Edc1. The DC output voltage Edc of the WM rectifier is controlled.
[0027]
Therefore, according to this embodiment, resonance generated on the output side of the PWM rectifier can be suppressed, and in a steady state where no resonance occurs, the DC output voltage of the PWM rectifier can be controlled to a command value, and the DC It is possible to improve the accuracy of the control of the output voltage.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress the resonance generated on the output side of the PWM rectifier, and to control the DC output voltage of the PWM rectifier with high accuracy in a steady state where no resonance occurs. .
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration example of a PWM rectifier controlled by an output control device for a PWM rectifier according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of an embodiment of an output control device of a PWM rectifier of the present invention.
3 is a waveform chart showing a waveform example of a main part of the block diagram of FIG. 2;
FIG. 4 is a block diagram showing a configuration example of a conventional output control device for a PWM rectifier.
5 is a waveform chart showing a waveform example of a main part of the block diagram of FIG. 4;
[Explanation of symbols]
D1 to D6 Diode Q1 to Q6 Transistor C1 Smoothing capacitor 11 Transformer 12 AC-DC converter 15 Load 16 AC power supply 17 Output control device 20 Current change rate calculator 21 Multipliers 22, 23 Subtractor 24 DC voltage regulator 25 Switching signal Generation circuit

Claims (2)

An output control method for a PWM rectifier including a semiconductor switching element that converts an alternating current to a direct current to generate direct current power and controls a direct current output voltage by switching control,
Detecting a temporal change in the DC output current output from the PWM rectifier, and calculating a correction value according to the degree of the change when there is a temporal change;
A target value of the DC output voltage output from the PWM rectifier is corrected by the obtained correction value,
Calculating a deviation between the corrected target value and the DC output voltage of the PWM rectifier,
A method of controlling the output of a PWM rectifier, wherein switching control of the semiconductor switching element is performed so that the obtained deviation becomes zero. An output control device for a PWM rectifier including a semiconductor switching element that converts an alternating current into a direct current to generate a direct current power and controls a direct current output voltage by switching control,
Rate-of-change calculating means for determining a time-dependent change in the DC output current of the PWM rectifier, and generating and outputting a correction signal having a correction value according to the degree of the time-dependent change,
Target value correction means for correcting a target value of the DC output voltage of the PWM rectifier with a correction signal of the change rate calculation means;
Deviation calculating means for calculating a deviation between the target value corrected by the target value correcting means and the DC output voltage of the PWM rectifier;
Switching signal generating means for generating a signal for switching the semiconductor switching element such that the deviation becomes zero according to the deviation obtained by the deviation calculating means;
An output control device for a PWM rectifier, comprising:

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