The influence of optimizing rotor on the performance and the iron loss of the permanent machine

Interior permanent magnet synchronous motor (IPMSM) is widely used because of its wide speed range and high precision performance. However, when it is operated in wide speed range especially in weak magnet and high speed stage, iron loses will cause the problems such as high temperature rising, low efficiency and so on. Moreover, the torque fluctuation caused by cogging torque not only affects the control accuracy but also generates noise and vibration. In order to improve the motor performance, it is necessary to optimize the structure of motor during motor design stage. To address these issues above, the rotor structure of IPMSM is optimized in this paper. Specially, non-uniform air gap is adopted during rotor design in order to obtain the optimal eccentricity. The optimized motor model is simulated by using 2D finite element method. The result verifies that not only cogging torque and torque fluctuation are reduced and the performance of motor is improved but also iron loses are reduced and efficiency is improved.