Shape optimization of rotor pole in spoke type permanent magnet motor for reducing partial demagnetization effect and cogging torque

Abstract

In this paper, a optimized rotor pole shape is proposed which can effectively reduce partial demagnetization effect and cogging torque. First, for reducing peak amplitude of the external field that directly affects to the partial demagnetization on the permanent magnets in spoke type permanent magnet motor, we conduct variation of core shape and insertion of barrier. Second, with the rotor shape which obtained by the first processes for the reducing partial demagnetization effect and the cogging torque, another part of rotor pole is varied to make better sinusoidal distributed air gap flux density. In process of designing the rotor pole shape, a steepest descent method and a response surface method are applied for convergence improving. The usefulness of the method is verified by the simulation results based on 2D finite element method.