ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM FOR VEHICLE AND METHOD AND SYSTEM FOR MOTOR CONTROL

摘要

A power steering device capable of obtaining a high rotary speed in the medium low torque range of an electric motor without incurring a drastic increase in manufacturing cost. The power steering device generates an auxiliary steerin g power by oil pressure that is generated by a pump which is driven by an electric power motor. The electric motor is a triple-phase brushless motor, with its angle of rotation being detected by the Hal1 sensors. The field coils are provided with the electri c current from a drive circuit which is driven by a drive signal from the motor drive control part. The motor drive control part controls the electric motor by PWM control in t he low medium speed rotation range and controls the electric motor by phase advance angle control, with PWM duty at 100 percent, in the medium high speed range.