Magnetizing Fixture Design for the Ring-type SPM Motor to Reduce the Torque Ripple

Abstract

This paper presents a design method to obtain an innovative structural design of a magnetizing fixture that can achieve a target magnetization orientation of a ring-type magnet of a surface-mounted permanent magnet (SPM) motor. The optimization problem is formulated to minimize the integrated value of the difference between the magnetic flux distribution produced by the input current of a magnetizing fixture and the target orientation for improving the torque performance of a SPM motor. Two level set functions are employed to express both the structural boundaries and the material properties of the ferromagnetic material (FM) and coil in a magnetizing fixture. To confirm its effectiveness, the proposed method is applied to the magnetization problem of a 8-pole 12-slot SPM motor designed for a battery cooling system of hybrid electric vehicles.