S. Nasr - Faculty of Electrical and Computer Engineering, University of Kashan, Kashan, Iran.
B. Ganji - Faculty of Electrical and Computer Engineering, University of Kashan, Kashan, Iran.
M. Moallem - Faculty of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, Iran.

kground and Objectives: Due to exclusive advantages of the permanent magnet synchronous motors (PMSMs) such as large torque/power density, high efficiency and wide speed range in constant power region, special attention has been paid to these motors especially for electric vehicle (EV) application. A conventional type of PMSMs which is more suitable for EV application is the interior permanent magnet synchronous motors (IPMSM). The main objective of the present paper is design optimization of this type of PMSM to increase efficiency and reduce torque ripple which are important for EV application. Methods: Using different shape design optimization methods including rotor notch, flux barrier and skewed rotor, design optimization of the delta-shape IPMSM is done and an optimized design is suggested first. One of the most important factors affecting the performance of the IPMSM is the magnet arrangement in the rotor structure. Based on the the design of experiments (DOE) algorithm, optimal values of some design parameters related to magnet are then determined to improve more the motor performance of the suggested structure.Results: The simulation results based on finite element method (FEM) are provided for a typical high-power IPMSM to evaluate the effectiveness of the proposed technique. In comparison to the initial design, ۷% increase of average torque, ۵۰% reduction of torque ripple and ۱.۴% increase of efficiency are resulted for the optimized motor. Conclusion: Using the proposed hybrid design optimization procedure (shape design optimization with optimum design parameters), significant improvement of some characteristics related to the delta-shape IPMSM including efficiency, average torque and torque ripple is resulted and this conclusion is desirable for EV application.

Interior Permanent Magnet Synchronous Motor, Electromagnetic Modeling, Design Optimization, Torque Ripple Reduction, Finite element method