Torque Characteristics Comparison and Analysis of Surface-Mounted Permanent Magnet Vernier Machines With Different Stator Topologies

Permanent magnet vernier machines (PMVM) have gained considerable attention due to its inherently high torque density and simple mechanical structure. In this paper, output torque characteristics among several stator topologies with different tooth features are investigated both by theoretical analysis and finite element analysis (FEA) in split-pole PMVM, which can provide valuable instructions for PMVM design. For a fair comparison, all the models are fully optimized and compared under same external conditions. The results shows that the stator topologies with relative small number of main teeth and auxiliary teeth possess more competitive output torque capability and flux weakening capability. Meanwhile, the geometrical variation of the flux modulation pole can produce extra working harmonics to enhance the output torque capability. It is found that there always exists the optimal combination among the angle of auxiliary teeth and slots to generate the maximum torque. Consequently, a parameter K is introduced to deliver the quantitative relationship among the angles and the range of K is evaluated and given. Finally, the results of theoretical analysis are verified through FEA method.