Analysis of a Novel Surface-Mounted Permanent Magnet Motor With Hybrid Magnets for Low Cost and Low Torque Pulsation

Abstract

This article presents a novel surface-mounted permanent magnet motor (SPMM) with hybrid NdFeB-Alnico magnets to achieve low cost and low torque pulsation. Based on the analysis of the effects of stator magnetomotive force (MMF) on rotor magnets, the Alnico magnets can be properly configured to avoid demagnetization. To reduce torque pulsation, three models with different slot-pole combinations are proposed and compared, with the aid of the finite element method (FEM), and the results show that the torque pulsation of the 27-slot/4-pole model is the lowest, which is selected for further optimization. The multi-objective genetic algorithm (MOGA) is adopted to optimize the usage of Alnico and NdFeB magnets, thereby improving torque performance and reducing the cost. To verify the effectiveness of the optimization, the optimized model with hybrid NdFeB-Alnico magnets is compared with other models with only NdFeB magnets under the same operating conditions. As a result, it shows that the optimized model can significantly reduce the cost of magnets while maintaining excellent torque performance.