Airgap Magnetic Field Harmonic Synergetic Optimization Approach for Power Factor Improvement of PM Vernier Machines

Permanent magnet (PM) vernier machine has excellent prospects because of its high torque density, whereas its power factor is lower than conventional PM counterpart. At present, power factor of PM vernier machine is mainly analyzed and improved from the perspective of either PM magnetic field or armature magnetic field individually. Also, synergetic effect of both PM and armature fields is rarely considered, thus limiting the power factor improvement. In this article, a synergetic optimization approach considering both PM and armature airgap harmonics simultaneously is proposed to improve the power factor of PM vernier machine. First, the power factor is analyzed from the both PM and armature airgap harmonics. Second, the proposed optimization framework is interpreted and implemented. Meanwhile, a PM vernier machine with rotor flux barriers is selected as a design example to investigate the effectiveness of the proposed optimization approach. Finally, a prototype machine is manufactured and experimented to verify the effectiveness of the proposed optimization approach.