Realizing high efficiency using pole-changing hybrid permanent magnet motors

It is necessary to reduce the power consumed by variable-speed motors in electrical appliances and electric vehicles in order to achieve energy saving. Thus, we developed a technique that changes poles in a permanent magnet (PM) motor based on speed. In this paper, we propose a novel pole-changing PM motor and discuss its basic configurations and principles. The proposed pole-changing PM motor has a permanent magnet that is magnetized by the magnetizing coil of the stator. The motor can magnetize just one of the permanent magnets so as to change the number of poles in the motor. Our analytical results confirm that a pole-changing PM motor can vary the induced voltage from 15% to 100%, reduce core loss by approximately 70% over a wide speed range, and increase the speed range in drive. Thus, the proposed motor is suitable for use in a variable-speed drive system to achieve high performance and efficiency.