Analysis and Modeling of Axial Leakage for Spoke-Type Hybrid Permanent Magnet Machines

Abstract

In this study, we propose a novel analysis method for a spoke-type permanent magnet (PM) synchronous motor (PMSM) using two types of PMs that consider axial leakage flux using a magnetic equivalent circuit (MEC). Spoke-type ferrite PMSM have the advantage of concentrating magnetic flux; however owing to the shape in which the PMs are arranged along the radial direction, some magnetic flux leaks in the axial direction, which causes inconsistency between the 2D and 3D finite element analysis (FEA) results. Because 3D FEA requires considerable analysis time, using it in the initial design stage of the motor is inefficient. Therefore, we present a new analytical method combined with MEC to overcome the existing inefficient approach. To obtain analysis results equivalent to 3D FEA, the new residual magnetic flux density considering axial flux leakage was applied to 2D FEA PMs using MEC and 2D FEA. The validity of the proposed method was verified through 3D FEA and experiments conducted on the test models using two magnet types.INDEX TERMS Axial flux leakage, ferrite permanent magnet motor, hybrid magnet, less-rare-earth motor, lumped magnetic equivalent circuit, spoke-type permanent magnet motor.