JPS61244274A - Control system of pwm converter - Google Patents

Abstract

PURPOSE:To reduce a current unbalance by providing a circuit for compensating the current unbalance at every unit PWM converter in addition to a batch (current) control circuit. CONSTITUTION:A harmonic wave contained in a power source system is detected, a plurality of unit pulse width modulation control converters (PWM converters) 1a, 1b are multiplexed in parallel to suppress harmonic waves with the harmonic wave as a current command value Iu*to control a current. The sum of the output current of the converter 1 and the deviation of the command Iu* are amplified by an error amplifier 2, fed to PWM controllers 3a, 3b, and the semiconductor switching element of the converter 1 is driven together with a carrier through a carrier output circuit 5 from an oscillator 4. In this case, individual controllers are formed of a proportional circuit 7, and an error amplifier 8 for amplifying the deviations between the output of the circuit 7 and the outputs Iu of the converters 1. Thus, since the batch current controller which mainly contains the amplifier 2 is higher than the carrier of the individual current controller, its gain can be enhanced higher than the amplifier 8.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a control method (
:Related.

[Technical background of the invention and its problems] Figure 2 1; As shown (For example, power supply system I: In order to detect the included harmonics and use this as the current command value υ to suppress the harmonics, There is a PWM conversion device (here, 2] 1 is shown as an example) in which current is controlled by multiplexing unit pulse width modulation control converters (hereinafter referred to as PWM converters or devices) 1g and 1b in parallel. .

When controlling the current in this device C: PWM converter la,
lb output current IUl, sum of Iυ2 and current command Iυ
The error amplifier 2 amplifies the deviation of
Obtain the WM converter output voltage command Ec. (Iul, Iυ2
(batch current control method). This voltage command Ec is sent to the PWM control circuits 3a, 3b (:,) of each PWM converter.

Also, the phase of each PWM converter 1a and lb is shifted based on the oscillator output C of 4: fc (phase difference of 360'/n).

n is the number of multiplexing) PW from a carrier wave output circuit with 5 carrier waves
The outputs C of M control circuits 3a and 3b are sent, and the semiconductor switching elements of PWM converters 1a and 1b are driven by the outputs C of 3g and 3b.

In this method, since the phase of the carrier wave is shifted (: respectively, the ripple current of the PWM converter output current IU1. Since the elements are smaller, the current control function has the advantage of being improved.On the other hand, as shown in FIG. It also has the disadvantage of causing current imbalance between PWM converters due to errors in reactor values and differences in initial current values.

[Object of the Invention] The object of the present invention is to provide a control method for a PWM converter that can achieve the above-mentioned advantages of collective current control and reduce current unbalance between unit PWM converters in a multiplexed PWM device. The purpose is to provide.

[Summary of the Invention] The present invention aims to reduce the current unbalance by providing a circuit for compensating for the current unbalance of each unit PWM converter in addition to the collective (current) control circuit.

[Embodiment of the Invention] Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention, and 7 in the figure is a proportional circuit that allocates the current command IU'' to each unit PWM converter (the output is normally /n, n is the number of multiplexing),
$a, gb are the output current of the valley PWM converter and 7, respectively.
This circuit compensates for current imbalance using an error amplifier that amplifies the deviation from the proportional circuit output.

Other components are the same as those shown in FIG.

When such a control method is implemented, the collective current control circuit mainly composed of the error amplifier 2 has an isometry fine wave of ga, 8b.
Since it is higher than the carrier wave of the individual current control circuit mainly composed of , the gain of the error amplification circuit 2 is
gb, and the control performance of the output current °, which is an advantage of the collective current control described above, can be maintained. Also 8a, gb
The gain of the error amplifier of the individual current control circuit configured as a king is lower than the gain of 2 because the dead time element is larger, but let's correct the unit PWM conversion converter flow command value (output of proportional circuit 7) C2 As a result, the current imbalance is improved (-).According to the authors' experiments, each unit PW
The current unbalance between M converters, which was about ±10 to ±20% without the compensation of the present invention, can be suppressed by about ±2 to ±3% by implementing the present invention. Approved.

[Effects of the Invention] As explained above, the present invention (according to Yu) provides a collective current control circuit and an individual current control circuit (-) to improve the output current control performance (current followability) as a device, In addition, the individual current control circuit (2) can correct the unbalance of the output current of each unit PWM conversion converter, making it possible to perform precise control.

In the case of a multiplex configuration, duplexing was explained above as an example, but nx
In this case, it can be easily inferred that it is sufficient to provide n individual current control circuits, n outputs of the carrier wave output circuit 5, and n PWM control circuits.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining the present invention in detail. Explanation of symbols la, lb -・-PWM converter 2.8a,
8t)...error amplifier 3a, 3b...PWM control circuit 4...oscillator 5...carrier output circuit 5a,
5b...Reactor 7...Proportional circuit agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] Multiplexed PW made by connecting multiple unit PWM converters in parallel
In the M device, the phase of the carrier wave is shifted for each unit PWM converter, and the current command value is matched with the sum of the (input) output current of each unit PWM converter so that this deviation output becomes zero. A collective current control circuit that controls a multiplexed PWM device, and a current command value for each unit PWM unit PWM device.
An individual current control circuit is provided to control the deviation output between the second current command value assigned to each current command value and the output (input) current of each unit PWM converter to zero.
The current of the multiplexed PWM device is controlled by controlling the current of each unit PWM converter in the M converter using the sum of the output of the collective current control circuit and the output value of the individual current control circuit for each unit. Characteristic control method of PWM conversion device.