Investigation of an Asymmetrical Rotor Hybrid Permanent Magnet Motor for Approaching Maximum Output Torque

This paper presents a new asymmetrical rotor hybrid permanent-magnet (AR-HPM) motor with good torque performances. Different from the traditional symmetrical rotor structure, the asymmetrical rotor structure is employed to improve the torque production. This makes the reluctance torque and the magnetic torque reach the maximum at the same current phase angle. Based on the concepts, the motor is investigated by the finite-element method (FEM). The frozen permeability method (FPM) is applied to divide the torque into the reluctance torque and the magnetic torque. The electromagnetic characteristics and torque performances of the motor are compared with a conventional motor. The results show that the proposed design is efficacious in boosting output torque at the same operating conditions. Moreover, the results also demonstrate that the topology of the proposed AR-HPM motor features the advantage of avoiding the risk of demagnetization.