JP2960569B2 - Control device for PWM converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a PWM converter used in a device for driving a main motor for electric railways.

[0003]

2. Description of the Related Art Conventionally, as a main motor driving device for an electric railway, which receives power from an AC overhead line, a PWM converter is used for AC-DC conversion, and DC-AC conversion of a variable voltage and variable frequency is further performed to obtain AC power for an AC main motor. A device using a variable voltage variable frequency inverter to supply electric power is widely used.

As a control device for PWM control of a PWM converter in such a conventional electric motor driving device for electric railway, an AC voltage detecting means for detecting an AC voltage of the input AC power, Current detection means for detecting the current of the DC power, DC voltage detection means for detecting the DC voltage of the DC power to be output, and an AC voltage detection signal, a current detection signal and a DC voltage detection signal of each of these detection means. A / D for digital conversion
The D / A converter includes a D / D converter, a processor that executes PWM control arithmetic processing of voltage and current using the current and voltage digital signals converted by the A / D converter, and a timer that instructs control start timing of the processor. Things are known.

[0005]

SUMMARY OF THE INVENTION Such a conventional PW
In the control device of the M converter, the control timing of the processor, that is, the cycle time is selected independently of the power supply frequency. As a result, the control timing of the processor is further reduced by the least common multiple between the power supply frequency and the sampling frequency determined by the processor cycle time. Most of the signals were to be superimposed on the n-th harmonic.

However, usually, signals such as ATC for electric vehicles are designed so that frequencies other than several times the power supply frequency do not leave the electric vehicle.
There has been a problem that frequency components other than several times the power supply frequency to be superimposed may adversely affect signal recognition.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a control device for a PWM converter in which harmonic components other than several times the power supply frequency are not superimposed on a signal. Aim.

[Structure of the Invention]

[0009]

According to the present invention, there is provided a PWM converter control device comprising: an AC voltage detecting means for detecting an AC voltage of input AC power; and a current detecting means for detecting a current of the input AC power. DC voltage detection means for detecting the DC voltage of the DC power to be output; AC voltage detection signal detected by the AC voltage detection means ; current detection signal detected by the current detection means; and DC voltage detection. A / D conversion means for analog-to-digital conversion of each DC voltage detection signal detected by the means, and PWM of voltage and current using the current and voltage digital signals converted by the A / D conversion means.
A processor for executing control processing to determine a control start timing of the processor, also the A / D conversion hand
The AC voltage detection signal, the current detection signal, and
A timer for determining a sampling timing of each of the DC voltage detection signals , the timer including a timer for giving a sampling frequency several times the power supply frequency.

[0010]

In the control device for a PWM converter according to the present invention,
AC voltage detection signal from each detection means, current detection signal, when performing the PWM control operation process using the respective detected DC voltage signal, San A / D conversion means outputs a timer
Predetermined sample timing based on the pulling signal
Each of these detection signals is taken in for each
Convert and passes it to the processor, and the processor is in timer
Predetermined control based on output sampling signal
The PWM control calculation is periodically performed at each start timing .

The timer supplies a sampling frequency that is several times the power supply frequency as a sampling frequency for determining each timing of the PWM control arithmetic processing of the processor. In addition, only the sampling frequency which is several times as high as the power supply frequency is used, and other frequency components are not superimposed on the signal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 shows a circuit configuration of a general AC mains driving apparatus for a mains motor for an electric railway. A pantograph 1, a main transformer 2, and a PWM converter 3 for performing AC-DC conversion for feeding from an AC overhead line. A variable voltage variable frequency inverter 4 for converting the DC power of the converter 3 into AC power having a variable voltage variable frequency; and a main motor 5 driven by the output of the inverter 4.

Further, 6 is a wheel, 7 is a converter control device, 8 is a current detector for detecting a secondary current of the main transformer 2, and 9 is an AC voltage detector for detecting a tertiary voltage of the main transformer 2. Reference numeral 10 denotes a capacitor, and 11 denotes a DC voltage detector.

In the electric motor driving device for electric railway, the electric power supplied from the pantograph 1 is input to the PWM converter 3 through the main transformer 2. And P
AC-DC conversion is performed by the WM converter 3 and supplied to the variable voltage variable frequency inverter 4 via the capacitor 10.

The variable voltage variable frequency inverter 4 generates a variable voltage variable frequency three-phase AC for driving the main motor 5 and drives the electric vehicle.

The control of the AC / DC conversion by the converter 3 is performed by the control device 7, and the control of the inverter 4
Is controlled by an inverter control device (not shown).

The control device 7 of the PWM converter 3 is shown in FIG.
As shown in the figure, the detection signal Is of the AC input current from the current detector 8, the detection signal Vs of the AC input voltage from the voltage detector 9, and the DC voltage detection signal Vs from the voltage detector 11.
d is input and has the configuration shown in FIG.

That is, A / D converters 12a to 12c for A / D converting the respective inputs Is, Vs, Vd, and an adder 1 for calculating a deviation between a voltage detection value Vd and a voltage command value Vd ^*.
3, a feedback control calculator 14, a multiplier 15, an adder 16 for calculating a deviation between the current detection value Is and the output of the multiplier 15, a feedback control calculator 17, an output and a voltage of the feedback control calculator 17 Detection value Vs
Adder 18 for calculating the deviation from the output Vc
Is compared with the carrier from the carrier generator 19, and a gate amplifier 21.

In addition, a timer 2 for providing a timing signal for periodically controlling the voltage and current of the control device.
2 are provided. Then, the final output from the gate amplifier 21 is output to the PWM converter 3 as a pulse signal, and the PWM control of the PWM converter 3 is performed.

Next, the operation of the control device for a PWM converter having the above configuration will be described.

In the circuit shown in FIG. 1, the current detection signal Is and the voltage detection signals Vs and Vd, which are analog inputs, are converted into digital values by A / D converters 12a to 12c, respectively, and thereafter processed as digital quantities. Will be.

First, the voltage detection value Vd is passed through an adder 13 to determine the difference from the voltage command value Vd ^* . The difference is compensated by k ₂ | s | in the feedback control calculator 14, and the secondary current peak value is calculated. Command Im ^* . Then, the secondary current peak value command Im ^* is multiplied by the unit sine wave sinθ that determines the phase of the secondary current in the multiplier 15 to obtain a current command value Is ^* , which is provided to the adder 16.

The adder 16 calculates the deviation between the current command value Is ^* and the current detection value Is, and further compensates for the deviation with k ₁ | s |
Subsequently, it is compared with the voltage detection value Vs, and the deviation is output as the converter output voltage Vc.

The converter output voltage Vc is compared with the carrier from the carrier generator 19 in the comparator 20 to form an on / off pulse, and this pulse signal is further amplified by the gate amplifier 21 to output the pulse signal of the PWM converter 3 shown in FIG. It is output as a control signal.

The timer 22 gives a timing signal so that the above-described voltage / current control operation is repeated at a constant period, that is, every cycle time Ts. FIG. 2 shows how the D converters 12a to 12c are controlled.

As shown in FIG. 2, at timing t1 triggered by the timer 22, the voltage / current control starts, and the data of the A / D converters 12a to 12c are updated. The A / D converters 12a to 12c are of an integral type, and the average value of the input values until the next trigger timing t2 is obtained from the trigger timing t1 by the timer 22, and the A / D converters 12a to 12c in the next cycle are obtained. Is output as the output value of.

In this embodiment, the timer 2
The sampling frequency Fs of 2 is set to n times (n is an integer) the power supply frequency F. That is, it is set so that the relationship of Fs = n · F is established.

Here, in a PWM converter system used for an electric vehicle, F = 60 Hz, Fs ≒
Since it is about 500 Hz, assuming that F = 60 Hz and n = 8,
Fs = 480 Hz can be selected.

Therefore, if this sample frequency of 480 Hz is selected, the least common multiple with respect to the power supply frequency of 60 Hz is as follows.
480 Hz. As a result, no harmonics other than an integral multiple of the power supply frequency are generated, no other higher-order harmonics are superimposed on the signal system, no signal interference occurs, and control stability is maintained. Can be held.

[0031]

As described above, according to the present invention, since the sampling frequency for controlling the voltage and current of the converter is set to several times the power supply frequency, the harmonic is an integral multiple of this power supply frequency. , And high-order harmonics do not occur, do not adversely affect the signal system, and highly reliable control is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the embodiment.

FIG. 3 is a circuit block diagram of a general electric motor driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pantograph 2 ... Main transformer 3 ... PWM converter 4 ... Variable voltage variable frequency inverter 5 ... Main motor 7 ... Converter control device 8 ... Current detector 9 ... AC voltage detector 11 ... DC voltage detector 12a-12c ... A / D converter 14 ... Feedback control calculator 15 ... Multiplier 17 ... Feedback control calculator 19 ... Carrier generator 20 ... Comparator 21 ... Gate amplifier 22 ... Timer

Claims (1)

(57) [Claims] 1. A control device for a PWM converter used as a drive device of a main motor for an electric railway, comprising: an AC voltage detecting means for detecting an AC voltage of input AC power; and detecting a current of the input AC power. Current detection means, DC voltage detection means for detecting a DC voltage of DC power to be output, AC voltage detection signal detected by the AC voltage detection means , current detection signal detected by the current detection means, and DC voltage detection means A / D conversion means for analog-to-digital conversion of each of the detected DC voltage detection signals, and a processor for executing a PWM control operation process of voltage and current using the current and voltage digital signals converted by the A / D conversion means If, determines a control start timing of the processor, also before
The AC voltage detection signal and the current detection by the A / D conversion means.
Output signal and DC voltage detection signal
A control device for a PWM converter, comprising: a timer for determining a sampling frequency, the timer providing a sampling frequency of several times the power supply frequency.