Weijia Wang

This paper proposes a novel interior permanent magnet (IPM) machine with asymmetrical PM configuration. Different from the traditional IPM counterparts, the proposed machine can perform a magnet axis shifted (MAS) effect. The magnet axis is shifted towards the reluctance axis so that a higher resultant torque capability can be obtained. Firstly, the configuration and the basic principle of the proposed machine are described. The design parameters are optimized to improve the torque capability, and the effect of the PM asymmetry ratio on the torque performance is then evaluated in detail. In addition, the major electromagnetic characteristics of the optimized machine are investigated and compared with those of the Prius 2010 IPM machine by finite element method (FEM). The results demonstrate that the proposed asymmetrical PM configuration can achieve the torque improvement due to the MAS effect.

This paper proposes a novel magnet-axis-shifted hybrid permanent magnet (MAS-HPM) machine, which features an asymmetrical magnet arrangement, i.e., low-cost ferrite and high-performance NdFeB magnets, are placed in the two sides of a “▽”-shaped rotor pole. The proposed magnet-axis-shift (MAS) effect can effectively reduce the difference between the optimum current angles for maximizing permanent magnet (PM) and reluctance torques, and hence the torque capability of the machine can be further improved. The topology and operating principle of the proposed MAS-HPM machine are introduced and are compared with the BMW i3 interior permanent magnet (IPM) machine as a benchmark. The electromagnetic characteristics of the two machines are investigated and compared by finite element analysis (FEA), which confirms the effectiveness of the proposed MAS design concept for torque improvement.