In order to investigate the influence of different magnetization modes on the electromagnetic performance of magnetic gear, four models of magnetic gear with different magnetization modes are established. The finite element method is used to simulate the four models and compare their performances. The distribution of magnetic flux lines, air gap magnetic field, harmonic distribution, static torque, and dynamic torque are calculated, respectively. The simulation results show that the coaxial magnet gear with Halbach array has larger air gap flux density amplitude, smaller air gap harmonic content, and higher output torque than the other three kinds of magnetic gears.

In order to solve the high harmonic content of permanent magnet synchronous motor (PMSM) for fitness car, a PMSM with built-in permanent magnet bridge is proposed in this paper. Compared with surface mounted permanent magnet synchronous motor (SM-PMSM), the proposed motor with permanent magnet bridge structure has lower harmonic content. The performance and magnetization angle of the proposed motor are compared and analyzed in detail. The results obtained from finite element analysis show that the permanent magnet bridge can increase the air gap magnetic field intensity, and different directions of magnetization will affect the amplitude of fundamental wave of air gap magnetic density. Moreover, it can reduce the total harmonic distortion (THD) and make the magnetic density waveform more sinusoidal. It is very beneficial to the smooth output of torque of fitness car.