Cogging Torque Analysis of a Special Multi-DOF Permanent Magnet Motor

The permanent magnet spherical motor is simpler in structure and control and smaller in size than the general multi-DOF motors. This paper presents an 8-pole 12-slot, and the stator structure with three layers of multi-DOF spherical permanent magnet motor (MSPMM). The finite element software is used to build the motor model, and the electromagnetic density diagram of the motor is obtained through simulation. Cogging torque is a characteristic of permanent magnet motor, the cogging torque of MSPMM was analyzed by analytical method. The rotational and deflecting cogging torques obtained by analytical method are compared with the finite element method. The figures obtained by the two methods are similar with only a small error, which verifies that MSPMM conforms to the theoretical law of the motor.