Calculation of the Iron losses in a Spoke-Type Permanent Magnet Synchronous In-Wheel Motor for Electric Vehicles by Utilizing the Bertotti Model

Abstract

This paper presents an analytical method for the calculation of the iron losses in a spoke-type permanent magnet synchronous in-wheel motor. According to the magnetic field distribution, the iron cores are divided into tooth, yoke, bridge, and shoe. Based on the boundary conditions of the subdomain model, the bridge is equivalent to the fan-shaped region with constant permeability. Then, the no-load and on-load magnetic fields in the air gap, tooth, yoke, bridge, and shoe are analytically calculated. The impacts of slotting and bridge saturation are considered. On the basis of the analytical expression of the magnetic fields, the iron losses of the tooth, yoke, bridge, and shoe are obtained by the Bertotti model. The analytical results in the no-load and on-load conditions are compared with that of the finite-element analysis. The validity is verified by the finite-element analysis.