MOTOR DRIVE DEVICE AND BRUSHLESS MOTOR

摘要

This motor drive device switches a synchronous motor including a stator having a motor winding wrapped therearound and a rotor holding a permanent magnet from synchronous operation having synchronous driving to position-sensor-less vector control in which the current applied to the motor winding is controlled on the basis of the position of the rotor. During a synchronous operation period, this motor drive device estimates an induced voltage error on the basis of a detected current and voltage, controls a current command amplitude so that the error of an estimated induced voltage and a target induced voltage calculated on the basis of an internal angle match, and switches to the sensorless mode after the error falls within a prescribed value. Further, during synchronous operation, the absolute value of the induced voltage error is reduced to within a prescribed value through the gradual reduction of the current command.