An Optimal Method for Minimizing Cogging Torque in Disc-Type Permanent Magnet Machines Using FEM and Genetic Algorithm

Cogging torque is one of the main reasons which cause ripple in motor's speed and torque. So the reduction of cogging torque must be considered in the design of permanent magnet machines. There are many existing techniques for reducing cogging torque in PM machines. This paper presents a new optimal method for cogging torque minimization by magnet shifting in disc-type PM machines. The impact of magnet shifting on cogging torque and torque output are discussed in disc-type PM machines. In order to reduce the cogging torque effectively while without being harmful to the average torque output. This paper used genetic algorithm (GA) to calculate the shift positions combined with slot-opening optimization to achieve the minimum cogging torque.