Drive control system for sensor-less motor

摘要

A drive control system, with PLL control, drives a rotatable multi-phase sensor-less motor by switching a current of a field coil of each phase depending on the rotating phase of the motor. When the motor is driven, a desired phase is selected as a detection phase, and a voltage induced on the coil of the detection phase is detected when power is fed for a predetermined time to the field coils other than the detection phase. A magnetic pole position is detected from the amplitude condition of the detected induced voltage. Based on this detection, the power-feeding phase of the motor drive is determined. Power feeding and pole position detection are performed alternately.