Stray Losses Analysis And Design Of Permanent Magnet Synchronousmotor For Electric Vehicle

Permanent magnet synchronous motors（PMSMs）have a series of advantages such ashigh efficiency, high power density, high torque density, high starting torque and so on.PMSMs have attracted great attention all over the world because it can meet the requirementsof electric vehicles traction system. Losses of PMSMs have played an important role in thedesign optimization and performance analysis of electric vehicles. Accurate calculation oflosses and their distribution before the design can help the optimization of motor design,which is meaningful for the improvement of motor performances. In this paper, the losses ofPMSMs are deeply analyzed as follows:First，losses in PMSMs are classified and the calculation method is given too. Then thestray losses in motors are calculated by using2D and3D finite element method. The straylosses distribution in permanent magnet motors are analyzed by changing motor’s air gaplengths, pole and slot combinations, slot opening width, which is in order to analyze theinfluence of these parameters on motor’s stray loss. The calculated results were verified bymeasured results too, and loss coefficients are deduced.Then, the influences of motor’s air gap, slot opening width, pole and slot combination,rotor structure to the losses have been calculated and analyzed, the variation rule of harmoniclosses caused by inverter harmonic current supply was summarized.Finally，according to the design requirements, a55kW PMSM which will applied inelectric vehicle is designed. During the design, the permanent magnet structure, stator coreand rotor core diameter are determined. The air gap length and the core length are designed tomake sure the motor possessing the best performance. At last the dimension of lightening holeis provided by the comparison of motor’s performance.