Nonlinear Analytical Analysis of External Rotor Permanent Magnet Synchronous Motor

This article proposed a nonlinear analytical model (NAM) for external rotor permanent magnet synchronous motor (ER-PMSM) considering both rotor and stator saturation. The improved magnetic equivalent circuit (IMEC) is introduced to accurately describe the saturation effect of rotor and stator. The air gap reluctance is replaced by magnetic flux source, and, therefore, the size of IMEC can be reduced while keeping high accuracy. For the air gap field calculation, the analytical solution will be obtained based on the modified boundary condition from the IMEC. The complex permeance function is extended to represent the slotting effect of ER-PMSM. Hence, the NAM will be numerically solved from the combination of IMEC and analytical air gap solution. Both finite-element analysis (FEA) and experiment demonstrate that the proposed model has high accuracy and requires little time.