JP2006325326A - Inverter apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter apparatus for supplying a load with a fixed voltage having a fixed frequency, and suppressing an oscillation of an input voltage due to an oscillation of a reactive current in an induction motor by adding a difference between the reactive currents before and after a first-order lag filter multiplied by a proportional gain to a frequency of a voltage instruction without a change in the magnitude of a voltage even if a frequency of an output voltage is transiently varied. <P>SOLUTION: The inverter apparatus 3 includes an error amplifier for multiplying an error between an instruction value and a detection value of an AC voltage by a control gain and outputting a voltage compensation, and a voltage instruction calculator for adding the voltage compensation to the instruction value of the AC voltage and outputting the compensated voltage instruction. The reactive current in an output current from the inverter apparatus is detected. The difference between the reactive currents before and after the first-order lag filter is multiplied by the proportional gain, and added to the frequency of the voltage instruction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inverter device that supplies a constant voltage and a constant frequency to a load.

FIG. 1 is a top view of an inverter device for supplying a constant voltage and a constant frequency to a load.
The inverter device 3 is configured to input a DC voltage from a DC power source 1 via a DC filter 2 and output an AC voltage to a load 5 via an AC filter 4.

  An error amplifier that outputs a voltage correction value by multiplying an error between the command value of the AC voltage and the detected value by a control gain, and a voltage command that outputs the correction voltage command by adding the voltage correction value to the command value of the AC voltage An arithmetic unit and a transformation rate computing unit that computes the transformation rate by dividing the correction voltage command by a value obtained by passing a first-order lag filter to the detected value of the DC voltage (see, for example, Patent Document 1).

JP Patent Publication No. 09-009642

  In the inverter device as described above, if the control gain is increased or the time constant of the first-order lag filter is shortened, the output voltage is less likely to fluctuate. If the constant is increased, the input voltage is less likely to vibrate. However, when the load is an induction motor, the input voltage will oscillate because the reactive current oscillates even if the control gain is lowered or the time constant of the first-order lag filter is increased.

  In order to solve the above-described problem, the present invention detects a reactive current of an output current of an inverter device, and calculates a voltage command value obtained by multiplying a difference between the reactive current and a value obtained by passing the reactive current through a first-order lag filter by a proportional gain Add to the frequency of.

The present invention has the following effects.
1. The frequency of the output voltage fluctuates transiently but does not change the magnitude of the voltage.
2. The vibration of the input voltage due to the vibration of the reactive current of the induction motor can be suppressed.

  By detecting the reactive current of the output current of the inverter device and adding a value obtained by multiplying the difference between the reactive current and the reactive current through the first-order lag filter by a proportional gain to the frequency of the voltage command, Although the frequency fluctuates transiently, vibration of the input voltage due to vibration of the reactive current of the induction motor can be suppressed without changing the magnitude of the voltage.

The present invention is applied to the inverter device of FIG.
As shown in FIG. 1, the main circuit includes an inverter device 3 that receives a DC voltage from a DC power source 1 through a DC filter 2 and outputs an AC voltage to a load 5 through an AC filter 4.

  The control method includes an error amplifier that outputs a voltage correction value by multiplying an error between an AC voltage command value and a detection value by a control gain, and adds the voltage correction value to the AC voltage command value to output a correction voltage command. A voltage command calculator for outputting, detecting a reactive current of the output current of the inverter device, and multiplying the difference between the reactive current and the reactive current through a first-order lag filter by a proportional gain, the value of the voltage command Add to frequency.

  The present invention relates to an inverter device that supplies a constant voltage and a constant frequency to a load, and the frequency of the output voltage fluctuates transiently, but the load is partly an induction motor without changing the magnitude of the voltage. The vibration of the input voltage that is easily generated can be suppressed.

Fig. 3 is a jump diagram of an inverter device that supplies a constant voltage and a constant frequency to a load.

Explanation of symbols

1 DC power supply 2 DC filter 3 Inverter device 4 AC filter 5 Load

Claims (1)

  An inverter device that inputs a DC voltage through a DC filter circuit and outputs an AC voltage through an AC filter circuit, and outputs a voltage correction value by multiplying an error between the command value and detection value of the AC voltage by a control gain. An error amplifier, a voltage command calculator that outputs the corrected voltage command by adding the voltage correction value to the command value of the AC voltage, and a value obtained by passing the correction voltage command to the detected value of the DC voltage through a first-order lag filter. In an inverter device having a transformation ratio calculator for calculating a transformation ratio by dividing, a reactive current of the output current of the inverter device is detected, and a difference between the reactive current and a value obtained by passing the reactive current through a first-order lag filter is obtained. An inverter device characterized by adding a value obtained by multiplying a proportional gain to a frequency of a voltage command.

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