A Multiple Working Harmonic PM Vernier Machine With Enhanced Flux-Modulation Effect

Permanent-magnet vernier (PMV) machines have been extensively researched in recent years due to their inherently high torque density. In this paper, a spoke-type PMV machine with multiple working harmonics is proposed. Due to the unaligned stator auxiliary teeth arrangement and carefully chosen slot-pole combination, working field harmonic with lower pole pair number is newly produced, which significantly enhances the flux-modulation effect. The proposed machine could achieve over 50% back electromotive force (EMF) and electromagnetic torque increment than its conventional counterpart. Through theoretical analysis and finite-element algorithm, the production of additional working field harmonics and their contributions to back EMF is quantitatively verified. Then, the electromagnetic performance of the proposed machine is further investigated and compared with several existing PMV machine topologies. Finally, the proposed machine is prototyped and verified by the experimental results as a promising PMV machine candidate.