Power conversion apparatus

Abstract

The invention aims at attenuating a magnetic flux sufficiently while stopping operation of a motor, so as to prevent excessive current and torque from occurring next time the motor is started, prevent excessive current and torque from occurring when attenuating the magnetic flux prior to stopping a power conversion apparatus, even if temperature fluctuation or change of constant occurs, without providing a magnetic sensor. A control unit of a power conversion apparatus includes a voltage operation part generating a voltage command driving the induction motor based on a current command, and a PWM operation part outputting the gate pulse signal based on the voltage command, and during cutoff from lowering to reaching zero of an excitation current command and a torque current command, the control unit sets an excitation current command during cutoff computed by adding an excitation current command correction quantity calculated according to a time variation of an excitation current command to the excitation current command, a magnetic flux command during cutoff obtained by multiplying the excitation current command by a gain, and the torque current command, as the current command with respect to the voltage operation part.

Description

technical field [0001] The present invention relates to a power conversion device for driving an induction motor. Background technique [0002] In the field of railway vehicles, induction motors are generally used as electric motors for driving vehicles. In railway vehicles, multiple electric motors are installed in the train. Even if the entire vehicle travels at the same speed, the rotation speeds of these electric motors are not necessarily the same due to the difference in the rotational radius of the wheels. When using a synchronous motor, since it is necessary to synchronize the rotation frequency of the rotor with the driving frequency of the power conversion device, a power conversion device is required for each motor. On the other hand, when an induction motor is used, since torque is generated according to the difference between the drive frequency and the rotational speed of the rotor, the rotational speed difference of the motor can be tolerated within the allow...

AI Technical Summary

Problems solved by technology

In this case, the magnetic flux sensor is not installed, and it is the sensorless case. However, since the value estimated from the motor constant etc. is used, if the constant changes due to the temperature fluctuation of the motor, the estimation error becomes large, and it may not be possible. Make the magnetic flux fully attenuated

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