JPH06327259A - Control circuit for power converter - Google Patents

Abstract

PURPOSE:To remove a noise component effectively by providing a plurality of kinds of filter circuits having constants different to one another in a voltage or current feedback system, and selecting them in accordance with the switchover of an output frequency. CONSTITUTION:A filter change-over switch 3 and a filter circuit 4 are provided between the AC/DC converter 2 and the voltage control circuit 5 of a feedback circuit for the output voltage of a power converter 1, in a variable voltage, variable frequency converter. This filter circuit 4 is composed of filters FL1-FLn having filter constants different to one another, and the filter change-over switch 3 selects one of them in accordance with the switch-over of the output frequency. In other words, when the output frequency is set to fset (f1-fn) with a frequency control circuit 7, a switch corresponding to this frequency is operated and one out of the filters FL1-FLn is selected, and the filter circuit 4 takes out only voltage signals near the output frequency effectively and gives them to the voltage control circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for controlling a power converter including an inverter and the like.

[0002]

2. Description of the Related Art Conventionally, in a device for arbitrarily controlling an output frequency and an output voltage such as a variable voltage and variable frequency converter (VVVF), for example, a filter circuit is used to remove a noise component contained in the feedback voltage. May be used.

[0003]

However, since the filter is conventionally used in the entire frequency region, noise components that cannot be removed remain depending on the output frequency, causing hunting and the like, which makes the control system unstable. May be. Therefore, it is necessary to adjust the gain of the control system each time, and there is a problem that complicated work is required. Therefore,
An object of the present invention is to improve control performance by removing noise components.

[0004]

In order to solve such a problem, in the first invention, a voltage control circuit for feedback controlling the output voltage of the power converter and a control for controlling the output voltage to a predetermined frequency. A frequency control circuit is provided, and in the control circuit of the power converter that controls the power converter based on the outputs of these control circuits, a plurality of types of filter circuits are selected for the voltage control circuit, and one of the filter circuits is selected. And a filter switching circuit for controlling a filter circuit according to the output frequency by the filter switching circuit.

According to the second aspect of the invention, the power converter is provided with a current control circuit for feedback controlling the output current of the power converter and a frequency control circuit for controlling the output current to a predetermined frequency, and based on the outputs of these control circuits. In a control circuit of a power converter for controlling the power converter, the current control circuit is provided with a plurality of types of filter circuits and a filter switching circuit for selecting one of the filter circuits, and the output frequency is controlled by the filter switching circuit. The feature is that the filter circuit is selected and controlled according to.

[0006]

[Function] The noise components are effectively removed and the control performance is improved by allowing the filter circuits provided in the voltage or current feedback system to have different constants according to the switching of the output frequency. Let

[0007]

1 is a circuit diagram showing an embodiment of the present invention. In the figure, 1 is a power converter such as an inverter, 2 is an AC / DC (AC / DC) converter, 3 is a filter switch consisting of an analog switch, 4 is a filter circuit, 5 is PI (proportional, integral). ) A voltage control circuit (AVR) including a regulator, 6 is a gate drive circuit, and 7 is a frequency control circuit (fcont).

That is, the power converter 1 is composed of a switching element such as an insulated gate bipolar transistor (IGBT) or a MOSFET. By turning on / off the switching element, a load such as a motor connected to the output side of the switching element is controlled. Driven. The output voltage of the power converter 1 is converted into a direct current amount by the AC / DC converter 2 and then A
Input to VR5, these AC / DC converter 2 and A
A filter switch 3 and a filter circuit 4 are provided between the VR 5 and the VR 5.

The filter circuit 4 is composed of filters FL1 to FLn having different filter constants, and the filter switch 3 selects one of them in accordance with the switching of the output frequency, so that the output frequency is fset.
When it is set to (f1 to fn), the switch corresponding thereto operates and one of the filters FL1 to FLn is selected according to this. Therefore, as the filter circuit, for example, a band pass filter or the like is used that can effectively take out only the voltage signal near the frequency when the output frequency is switched.

Since the output of the filter circuit 4 is given to the AVR5, the AVR5 outputs it to the voltage set value Vset.
A predetermined adjustment calculation is performed so that AVR5
Output of the gate drive circuit 6 is provided to the gate drive circuit 6 together with the output from the frequency control circuit 7.
Then, a signal for driving the switching element of the power converter 1 is generated from these signals, and thereby the switching element of the power converter 1 is turned on / off. Although the case of controlling the output voltage and frequency has been described above, the present invention can be applied to the case of controlling the output current and frequency in the same manner as above.

[0011]

According to the present invention, since the filter circuit is switched according to the output frequency, the noise component included in the detected output voltage or the output current is effectively removed, and stable control is possible. The advantage that the control performance can be further improved is obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric power converter, 2 ... AC / DC (AC / DC) converter, 3 ... Filter switcher, 4 ... Filter circuit, 5 ... Voltage control circuit (AVR), 6 ... Gate drive circuit, 7 ... Frequency control circuit (Fcont).

Claims (2)

[Claims] 1. A power converter is provided with a voltage control circuit for feedback-controlling the output voltage of the power converter and a frequency control circuit for controlling the output voltage to a predetermined frequency, and the power converter is based on the outputs of these control circuits. In a control circuit of a power converter for controlling, a plurality of types of filter circuits are provided in the voltage control circuit, and a filter switching circuit that selects one of the filter circuits is provided.
A control circuit for a power converter, characterized in that a filter circuit according to an output frequency is selected and controlled by the filter switching circuit. 2. A power converter is provided with a current control circuit for feedback controlling the output current of the power converter and a frequency control circuit for controlling the output current to a predetermined frequency, and the power converter is based on the outputs of these control circuits. In the control circuit of the power converter for controlling, the current control circuit is provided with a plurality of types of filter circuits, and a filter switching circuit that selects one of the filter circuits,
A control circuit for a power converter, characterized in that a filter circuit according to an output frequency is selected and controlled by the filter switching circuit.