Influence of magnet grouping in reduction of cogging torque for a slotted double-rotor axial-flux PM motor

This study is about minimization of cogging torque in an axial flux permanent magnet (AFPM) motor with integer number of slots per pole per phase with the focus on pole shifting or grouping. The analyses of cogging torque component are presented and compared with other cogging torque minimization methods and a reference AFPM motor with standard fan-shaped magnets. It is shown that magnet grouping is an effective method to eliminate cogging torque component in AFPM motors.