Cogging torque of permanent magnet electric machiens: An overview

Permanent magnet electric machine (PMEM) is widely employed in variety of applications because of their numerous advantages beyond other electric machines. Cogging torque is caused by the reluctance change between the stator teeth and magnet poles on the rotor, this is an inherent characteristic of PMEM. In many applications, cogging torque has become one important design specifications and consideration issues of PMEM. Study of cogging torque calculation methods and the cogging torque reduction measures are becoming more and more important nowadays. In this paper, the cogging torque calculation methods are introduced, and various practical cogging torque reduction measures are studied and compared.