Two-phase sonsorless brushless DC motor - design and control

Abstract

This project describe mathematical method which look for optimized electromagnetic torque with reduced ripple in both single-phase and two-phase brushless dc motor with special rotor construction. The conventional two phase two – pulse brushless dc motor requires special construction with aim to realize successful starting and ensuring relatively constant torque independent of the rotor position, there method are described: 1- Pulse width modulation (PWM) control strategy with skewed stator poles, which introduce unsymmetrical airgap magnetic, permance and thus additional reluctance torque eliminated low-order current harmonics. 2- PWM control strategy with symmetrical stator poles and shorted coil pitch. 3- Combined PWM and continuous control signal energized two-phase three – winding motor and unsymmetrical rotor construction, where it is expected producing electromagnetic torque with reduced ripples and increasing stability , independent of the rotor position.