SENSORLESS BRUSHLESS MOTOR

摘要

In a brushless motor of the kind not employing a sensor for detecting rotor position, a rotational reference position of the rotor is detected based on an induction voltage in a stator excitation coil, and an energization switching point of the stator excitation coil is determined to occur a delayed time from the reference position. The time delay is increased or decreased in response to the rotational speed of the motor, so that energization switching of the excitation coil is performed at the optimum position in accordance with corresponding changes in the rotational speed of the motor. Signal masking is performed so that noise generated by the excitation coil switching does not interfere with the detection of the rotor reference position.