Dual winding method of a BLDC motor for large starting torque and high speed

This paper presents a novel winding method and its inverter circuit to drive a brushless dc (BLDC) motor to high speed with large starting torque. The proposed winding coils are composed of dual windings, i.e., main and auxiliary windings, and the proposed inverter circuit has nine switches. In the starting period, it energizes both main and auxiliary windings in parallel connection to generate large starting torque. After the motor is accelerated, the proposed inverter circuit is automatically switched to energize main winding, which generates small back-electromotive force, to reach high speed. The proposed method is applied to the spindle motor of a hard disk drive and its effectiveness is verified through experiment.