Improving the torque characteristics of interior pm synchronous motor using an asymmetric on-off method on the rotor surface

In this paper, a novel technique for improving the torque characteristics of the Interior Permanent Magnet Synchronous Motor is proposed using rotor shape optimization. The main objective is to decrease the torque ripple while increasing average torque. The improvement process is performed for the maximum torque-angle operating point, and then studies are carried for other currents and angles. Defining a multi-element grid on rotor surface regions in which each element could be either iron or air, the best practical rotor surface topology could be obtained to improve the overall torque characteristics of IPMSM. The best motor performance is achieved using practical rotor shapes obtained from a cluster of points in average torque versus torque ripple plane. Finally, for torque ripple cancellation, two or three alternate rotor configurations with optimized average torque and out of phase torque pulsation have been selected. This selection will guarantee improved average torque while mitigating torque pulsation by a significant margin. Using this method, a rotor topology obtained in which torque ripple is reduced by 80% with slightly improved average torque. © 2017, Electromagnetics Academy. All rights reserved.