Investigation of Consequent-Pole Permanent Magnet Vernier Machines with IPM Structures

Consequent-pole permanent magnet vernier (CP-PMV) machines feature high torque density and low magnet consumption. In this paper, the characteristics of CP-PMV machines with interior PM (IPM) structures are investigated. Three CP-IPMV machine topologies with different PM structures are comparatively analyzed, including V-shaped PMs, U-shaped PMs, and spoke-array PMs with alternating flux bridges. To make a comprehensive comparison, a synthesis analytical model based on a magneto motive force (MMF)-permeance function is proposed to analyze the relationships of electromagnetic performance with key design parameters. The effect of a biased pole arc is also considered in the analytical model. Besides, influences of pole ratio, pole arc, PM dimensions, and slot opening ratio on torque performance are studied by finite element analysis (FEA). Moreover, to investigate the superiority of the CP-IPMV machine, three CP-IPMV machines with different PM types are compared to a regular IPM machine in terms of back-EMF, torque performance, power factor, etc. It is proved that the CP-IPMV machine exhibits high torque density, low torque ripple, high power factor, and flux-weakening capability, especially the CP-IPMV machine with VPM type. The analytical and FE results are validated by experiments.