Performance Analysis of a Hybrid-Magnetic-Pole Variable-Flux Machine

A hybrid-magnetic-pole variable-flux machine (HMP-VFM) is proposed in this paper. The low- and high-coercive-force magnets are utilized in the rotor in V-shape alternately, and each kind of magnets forms a magnetic pole. The proposed machine features the capability of changing the magnetization state of the low coercive-force (LCF) magnetic poles via stator winding. The structure of the machine and operating principle of the LCF magnet are given, and the electromagnetic performance, including magnetic field distribution, no-load air-gap flux density, back electromotive force (EMF) and torque-angle characteristics, in different magnetization states is investigated by finite element method (FEM). Besides, the torque-speed curves and efficiency maps are calculated, and the results show that the HMP-VFM can operate over a wide-speed range with high efficiency.