Optimal Design of Internal Permanent Magnet Motor for Starter/Generator of Hybrid Electric Vehicle

An internal permanent magnet (IPM) motor may be used as a suitable electric vehicle drive. This paper presents the results of optimal design of such machine as starter/generator of a hybrid electric vehicle (HEV). The required performance in HEV is a constant power over a wide speed range. In IPM machine, direct control of the PM flux is not possible but d-axis armature current can weaken the air gap flux. However, in this method, demagnetization effect caused by the reaction of the above mentioned current must be prevented. The vector control method is used in order to extend the performance range of the IPM motor. Efficiency and performance characteristics are considered as objective functions and an optimal design technique is applied to maximize the efficiency and achieve a good performance. Genetic algorithm is employed as optimization routine in order to find the optimum design variables of the objective function