Using Modular Poles for Shape Optimization of Flux Density Distribution in Permanent-Magnet Machines

A modular configuration for a type of permanent-magnet pole is proposed for use in permanent-magnet (PM) machines. The pole consists of three or more permanent-magnet pieces. The main objective of this configuration is to shape the air-gap flux density distribution produced by the pole. An optimization procedure based on an analytical model is then used to determine the optimal pole specifications. A finite-element method is finally carried out to evaluate the proposed configuration. Extensive investigations on a linear permanent-magnet motor demonstrate that the proposed configuration reduces flux density as well as back electromotive force harmonics. This pole configuration also results in more efficient use of PM materials.