关键词: 轴向式磁场调制永磁齿轮, 气隙磁通密度, 电磁转矩, 子域法

Abstract: AFMPMGs had serious axial and tangential leakages and low torque density. Based on AFMPMG, an external magnetic ring was introduced to make it a dual-excitation modulation AFMPMG(DEM-AFMPMG) structure. As the DEM-AFMPMG low-speed permanent magnet rotor was clamped between the inner and outer magnetizing rings, the axial and tangential leakage flux of the AFMPMG could be converted into useful harmonics, which increased the output torque and torque density of the DEM-AFMPMG. Although the 3D finite element method taken into account the magnetic leakages at the end of permanent magnet gears and had the advantage of high calculation accuracy, it also maked the occupancy of computer resources too high and the optimization period of structural parameters too long. A mathematical and physical model for calculating DEM-AFMPMG air gap magnetic field and electromagnetic torque was proposed herein based on subdomain method. This method could equate the 3D model to the 2D model, but all factors of the 3D model were included, so that the calculation accuracy was equivalented to that of the 3D finite element. The calculation examples show that the calculation accuracy based on subdomain method is equal to that of 3D finite element method(the calculation errors of air gap magnetic density and electromagnetic torque are less than 5% and the calculation errors of torque density are less than 1.5%), but the calculation speed of subdomain method is faster and it is easy to realize computer programming, which facilitates the analysis and optimization of structural parameters of DEM-AFMPMG. 

Key words: axial field modulation permanent magnet gear(AFMPMG), air-gap magnetic tightness, electromagnetic torque, subdomain method