Magnetising fixture design for optimal magnetisation orientation of ring-type magnet in surface-mounted permanent magnet motor

Abstract

This study presents a design method to obtain an innovative structural design of a magnetising fixture that can achieve a target magnetisation orientation for a ring-type magnet of a surface-mounted permanent magnet (SPM) motor. The optimisation problem is formulated to minimise the integrated value of the difference between the magnetic flux distribution, produced by the input current of the magnetising fixture, and the target orientation that improves the torque performance of SPM motor. Two level set functions are employed to express both the structural boundaries and the material properties of the ferromagnetic material and coil comprising the magnetising fixture. The optimal shape of the fixture is obtained by using an adjoint design sensitivity and a time evolution equation for each level set function. To confirm the effectiveness of the proposed method, it is applied to a magnetisation problem for an 8-pole 12-slot SPM motor designed for a battery cooling system in a hybrid electric vehicle.