Hitachi, Ltd.

Hitachi Keiyo Engineering Co., Ltd.

Hitachi Keiyo Eng. Co., Ltd.

Sadayuki Igarashi

Hiroshi Nagase

Hisakazu Ninomiya

Hiroyuki Tomita

Satoshi Ibori

Hiroshi Sugai

Sumio Kobayashi

A control apparatus for an induction motor wherein an inverter is connected between a power source and the induction motor so as to energize the induction motor through the inverter, characterized in that when an input voltage of the inverter has lowered, a magnetizing current component command is decreased, while a torque current component command is increased.

Control apparatus for induction motor

When driving an AC motor with a PWM inverter, the width of a speed command signal is modulated by a carrier to produce width modulated pulses for controlling main switching elements. The width modulated pulses are liable to be attended with impulses which cause magnetic vibrations in the AC motor, resulting in noises. The generation of these impulses can be suppressed by changing the amplification factor of an amplifier for the speed command signal or the amplitude of the carrier on the basis of the rate of change of the speed command signal. Noises which would be attendant on low speed running of the AC motor can be reduced by changing the amplification factor of the amplifier and the amplitude of the carrier on the basis of detected frequency of the speed command signal or revolution of the AC motor during low speed running.

Control apparatus for AC motors

Growing community of inventors

Funabashi, Japan

Sadayuki Igarashi