In this thesis, Microscopic Force Analysis of an Interior PM Synchronous Motor is proposed for shape improvement of the rotor air-bridges and rotor surface in order to improve the torque characteristics. Main objectives are to obtain the information of the force distribution profile of where the effective motional force inserted and how to change the shape of flux barriers in order to increase torque and decrease the torque ripple. Normal and tangential components of flux density are extracted by Finite Element Method on proper contours. Then force components on these surfaces are calculated using Maxwell Stress Tensor method. In the second step, improvement in the motor performances is achieved using air-bridge shape improvement according to the local force distribution. Finally the best shape of air barriers based on this analysis is obtained. With new air bridge shape, 16% increase in average torque and 34% reduction in torque ripple are obtained. For torque ripple cancellation, some alternate rotor configurations with optimized average torque and out of phase torque pulsation have been proposed. 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. Key Words Torque ripple, shape optimization, Maxwell stress tensor method, Microscopic force analysis.
