Abstract:

With the merits of high torque density and simple construction, permanent magnet vernier machines(PMVMs) are widely used in low speed and high torque drive fields such as electric ships and wind power generation. In order to further increase torque density, the torque characteristics of PMVM are analyzed by using the air-gap magnetic field modulation theory. The analysis of the effective coupling process between PM field and armature reaction field reveals that the torque generation mechanism of the PMVM. According to the relationship between the structure parameters and the magnetomotive force, permeance distribution, the parameters to be optimized are determined. The response surface method and genetic algorithm are combined to conduct multi-objective optimization of the torque performance of the PMVM. The Maxwell stress tensor method is employed to quantitatively analyze the electromagnetic torque contributions of the air-gap magnetic density harmonics, and the results prove that the electromagnetic torque of PMVM is generated by a single air-gap magnetic density working harmonic. On this basis, the influence of key structure parameters on the air-gap field modulation effect and torque characteristics of the PMVM is studied, which provides a theoretical basis for the topology structure innovation and torque performance improvement of this kind of machine.

Key words: Permanent magnet vernier machine(PMVM), air-gap magnetic field modulation, stress tensor method, harmonic analysis, torque characteristics