Research of Optitmum Design of Surfaced-Mounted-PMSM by Finite Element Method

1.表贴式永磁电机的有限元仿真利用2000年国家资助项目购置的微机，建立了考虑永磁电机磁路非线性的有限元分析系统，对表贴式永磁电机内部的涡流分布进行了详细的仿真。对于电动汽车的真实的运行模式，即恒转矩运行和恒功率（弱磁运行），电机中的涡流损耗是定量的。结果证实，由于绝缘PM，损失减少。另一方面，利用商用有限元软件对永磁电机的三维磁场进行了分析，明确了定子绕组端部线圈内的磁场分布，并通过转子永磁体的倾斜度说明了磁阻力的减小.永磁电机优化设计的建立将NdFeB等稀土永磁体表面镀Ni或Al，研究了镀Al和Ni的永磁体有限元网格划分及Ni镀层的磁饱和对永磁体涡流的影响。得到了表贴式永磁转子的有效设计方案。对凸极型永磁电机的优化设计进行了研究，发现凸极型永磁电机适合作为无位置传感器电机.基于上述设计思想，于2001年设计并制造了1.3kW表面贴装式永磁电机。试验电机为8极，转子由分段永磁体组成。转子的永磁体由稀土永磁体NdFeB制成，表面镀Ni。目前，设计的有效性已通过试验电机得到验证.

1. FEM Simulation of Surfaced-Mounted-PM SMPersonal computer was purchased by grant-in-aid in 2000, FEM analytical system taking into account of nonlinear magnetic circuit of iron and PM in PM motors was constructed, and then eddy currents distribution inside the surfaced-mounted-PM motor was simulated in detail. For real operation patterns of electric vehicles, which are the constant torque operation and the constant power (field weakening operation), the loss of eddy currents was clear quantitatively in the motor. In results the reduction of the loss was confirmed due to the insulated PM' s. On the other hand, the three dimensional magnetic field of PM motor was analyzed by commercial FEM soft, the magnetic field inendcoi1ofstatorwinding was made clear and the reduction of detent force was shown by the rotor PM skew.2. Establishment of optimum design for PM motorThe rare earth magnet such as NdFeB is coated with Ni or Al. An influence of Al- and Ni-coating FEM mesh of coated-PM and magnetic saturation of Ni-coatingon eddy currents in PM was investigated. In results, the available design of surfaced-mounted-PM rotor was obtained. Also the optimum design of salient type PM motor was investigated, and found suitable as a position-sensorless motor.3. Construction of the surface-mounted-PM motorOn the base of the above design concepts, 1.3 kW PM test motor was designed and constructed in 2001. The test motor has 8poles, and the rotor consists of segmented PMs. The PM of rotor was made from the rare-earth-magnet NdFeB and coated with Ni. Now the availability of design has been verifying by test motor.