Modeling of Uneven Air Gap Magnetic Field for Disc Planetary Permanent Magnet Machine With Segmented Gap Halbach Array

A new analytical magnetic circuit hybrid model (AMCHM) is proposed to predict uneven air gap magnetic field for disc planetary permanent magnet machine (DP-PM machine) with segmented gap Halbach array. The 3-D model is transformed into 2-D model by using radial sectors-of-rings division method and coordinate transformation. The 2-D magnetic field model is obtained by analytical method, and the magnetic equivalent circuit (MEC) model is used to consider the leakage flux loops with and without magnetic coupling. Finally, the analytical models of uneven air gap magnetic field and torque are obtained. The results obtained from proposed model are in good agreement with those of 3-D finite element method (FEM), which verifies the validity of AMCHM. Compared with 3-D FEM model, the AMCHM is convenient for the analysis and optimization of structure parameters, and it improves the calculation efficiency. The research results can be utilized for the research on structural optimization and power analysis.