Design and Analysis of a New Less-rare-earth Permanent Magnet Motor with Axial Hybrid Rotors

In this paper, the design and analysis of a new less-rare-earth permanent magnet (LRE-PM) motor with axial hybrid rotors is presented. By incorporating the advantages of a spoke-type non-rare-earth PM (NRE-PM) motor and a surface-mounted rare-earth PM (RE-PM) motor, the proposed LRE-PM motor features a low cost with high performance. In particular, two types of rotors are reasonably assembled axially together. By optimizing the alignment angle and the axial length ratio of two rotor sections, the total torque can be effectively improved with the higher utilization of the reluctance torque. In addition, the inductance characteristics can also be optimized to improve the flux-weakening ability. In addition, a conventional spoke ferrite-PM motor and a surface-mounted NdFeB-PM motor are adopted for comparison in the same size and working point. The FEM analysis results finally demonstrate that the proposed LRE-PM motor has high efficiency, low torque ripple, and high anti-demagnetization capability.