Design Optimization and Comparative Study of a Novel Halbach Permanent Magnet Vernier Machine with Alternate Flux Bridge

The purpose of this paper is to investigate the effect of the alternate flux bridge combining Halbach array in Vernier machines. The key novelty is that integrated with the Halbach array PM, the alternate flux bridge design can not only provide a flux path for low-order harmonics but also effectively improve the torque density of the machine. Together with the other three traditional structures under the same overall size, current density, and PM usage, the proposed structure is optimized by genetic algorithm (GA) to maximize the average torque and minimize the torque ripple. With the winding configuration of full-pitch (FP) and short-pitch (SP), the back-EMF, efficiency, power factor, and other performances of four machines with different topologies are analyzed and compared, respectively. With 2D time stepping finite element analysis (FEA) and experimental verification, the torque density of the proposed design reaches 40.11 KNm/m3, which is significantly higher than that of its existing counterparts.