Development a Novel Permanent Magnet Vernier Machine with High Magnet Utilization Employing Bottom-Sinusoidal Pole Pattern

This paper presents a novel permanent magnet vernier machine (PMVM) with bottom-sinusoidal pole pattern (BSPP). With the proposed configuration, the magnet utilization of surface-mounted PMVM could be greatly improved due to the reduction of high-order airgap flux density harmonics. Moreover, the increase of fundamental flux component helps to improve torque generation well. Additionally, the magnet poles are semi-embedded into the rotor, and thus the sleeve in conventional surface-mounted machines is no longer necessary, which helps to reduce the airgap size and improve the torque output further. Besides, modulating the airgap magnetic field by changing the bottom shape of the embedded magnets could effectively suppress torque ripple compared to the consequent pole configuration. Studies have been conducted on the novel structure to validate its advantages. Firstly, the topological structure and working principle of the BSPP vernier machine are presented. Then, the influence of the BSPP structural parameters on the torque performance is investigated. Subsequently, one PMVM with bottom-sinusoidal pole pattern is designed. Finally, the electromagnetic characteristics, such as flux density distribution, back EMF, average torque, cogging torque and torque ripple of the proposed machine are analyzed and compared with those of conventional PMVM with opening slot.