关键词: 永磁同步电机, 两极平行充磁, 环形永磁体, 磁场分布, 解析计算

Abstract:

Two-pole parallel magnetised ring-shaped permanent magnets (RSPMs) with non-magnetic conductive shafts were taken as the study objects. The analytical formulas of the magnetic fields produced by the RSPMs placed in the stator bore and air were deduced in the polar coordinate system. According to the material and structural characteristics, the whole solution field domain were divided into different regions which are expressed by the corresponding governing functions respectively. The general solution of vector magnetic potential for each region was obtained by solving the Laplace's equation or Poisson equation. The relevant coefficients in the general solutions were obtained using the boundary conditions and interface conditions and then the analytical model of the magnetic field distribution of each region. Taking a 2 pole-24 slot parallel magnetised ring-shaped permanent magnet synchronous motor (RSPMSM) with a non-magnetic conductive shaft as example, the magnetic field distributions obtained by the analytical model were compared with those by the finite element method, which verifies the correctness of the analytical model. In addition, the effects of rotor dimensions on radial flux density were discussed on the basis of the analytical models. By using the analytical models, the open-circuit magnetostatic field can be quickly and precisely calculated during early stage of the initial design of permanent magnet synchronous motors of this kind and the magnetisation results of the permanent magnet rotors of this kind can be evaluated.

Key words: permanent magnet synchronous motor (PMSM), two pole parallel magnetisation, ring-shaped permanent magnet(RSPM), magnetic field distribution, analytical calculation