Cogging Torque Reduction for Outer Rotor Interior Permanent Magnet Synchronous Motor

With the characteristic of high precision, good regulation-speed performance, high efficiency, high stability and reliability, outer rotor Interior Permanent Magnet Synchronous Motor (IPMSM) has been widely used in the machine tools, robotics, automotive electronic control field and other servo applications. In this paper, two methods to reduce the cogging torque are proposed. The first method is to minimize the fluctuation of air gap and torque ripple by optimizing the shape of flux-barrier. The second method to reduce the cogging torque is to slot the rotor. For the accurate calculation of torque distortion, Finite-Element Method (FEM) is used. In the final, the effect of these two methods on motor performance is analyzed. The results show that these two methods can greatly reduce the cogging torque, while ensuring that other performance parameters are in the best range.