US 2012/0056569 A1 · CONTROL DEVICE AND CONTROL METHOD FOR AC MOTOR

Abstract

A control device for performing PWM control of an inverter includes a synchronous PWM control circuit for generating a control command for the inverter by performing PWM control based on a comparison between a sinusoidal voltage command signal for operating the AC motor according to an operation command and a carrier signal, and a carrier generating unit for keeping an integer as a synchronization number being a frequency ratio between the voltage command signal and the carrier signal, and producing the carrier signal by switching the synchronization number according to an operation state of the AC motor. The carrier generating unit adjusts a phase relationship between the voltage command signal and the carrier signal according to the synchronization number such that an AC current transmitted between the inverter and the AC motor according to the control command provided from the synchronous PWM control circuit is symmetrical with respect to a boundary between positive and negative portions.

Claims8

Dependent claims

A control device for an AC motor supplied with a voltage controlled by an inverter, comprising:

a pulse width modulation control unit for generating a control command for said inverter by performing pulse width modulation control based on a comparison between a sinusoidal voltage command signal for operating said AC motor according to an operation command and a carrier signal;
and
a carrier generating unit for keeping an integer as a synchronization number being a frequency ratio between said voltage command signal and said carrier signal, and producing said carrier signal by switching said synchronization number according to an operation state of said AC motor, wherein
said carrier generating unit adjusts a phase relationship between said voltage command signal and said carrier signal according to said synchronization number such that an AC current transmitted between said inverter and said AC motor according to said control command provided from said pulse width modulation control unit is symmetrical with respect to a boundary between positive and negative portions.

1 more element

A control method for an AC motor supplied with a voltage controlled by an inverter, comprising the steps of:

generating a control command for said inverter by performing pulse width modulation control based on a comparison between a sinusoidal voltage command signal for operating said AC motor according to an operation command and a carrier signal;
and
producing said carrier signal by switching a synchronization number being a frequency ratio between said voltage command signal and said carrier signal according to an operation state of said AC motor while keeping an integer as a synchronization number, wherein
said step of producing said carrier signal adjusts a phase relationship between said voltage command signal and said carrier signal according to said synchronization number such that an AC current transmitted between said inverter and said AC motor according to said control command is symmetrical with respect to a boundary between positive and negative portions.

1 more element

Dependencies are inferred from the claim text.

Control device and control method for ac motor

Life of this patent

Control device and control method for ac motor

Life of this patent

Abstract

Claims8