Comparative Study of High-Current-Density High-Speed Vernier Permanent Magnet Machines for Electric Vehicle Traction Application

So far, vernier permanent-magnet machines (VPMs) are mostly applied in natural-cooling slow-speed applications, such as wind power generation, servo system, etc., which are designed with low current density and rotation speed. However, for high current density and rotation speed application, such as electric vehicle (EV) traction, the performances of VPMs are unknown. This paper will validate the feasibility of VPMs in EV traction application, and comparatively study the performances of high-current-density high-speed VPMs at different working conditions. These VPMs share the same stator core and winding, but with different rotor PM configurations, which include surface-mounted, embedded, V-shape and spoke-shape. Besides, the optimal VPM is also compared with a regular interior V-shape PM machine, which is commonly used in EV traction application. It shows that the VPM has higher torque density and efficiency, lower cogging torque and torque ripple than the regular PM machine.