低速直驱外转子永磁同步电机的设计

永磁同步电机具有转矩密度高、功率因数高的特点，极对数的增加也不会降低功率因数，但齿槽转矩的存在，影响输出转矩的稳定性。本文设计了一台72槽60极400kW的直驱外转子永磁同步电机，利用ANSYS Maxwell建立的二维有限元仿真模型，分析空载反电势、齿槽转矩、气隙磁场、同步电感和负载转矩，验证了电机结构和参数的合理性。重点研究了齿槽转矩和转子损耗的优化，采用优化定子齿槽宽度和开辅助槽的方法，削弱齿槽转矩，采用转子磁极分块的方法，限制涡流通过路径，以降低转子损耗。仿真结果表明，所设计的电机能够满足性能指标，为电机的设计、齿槽转矩和转子损耗的优化提供了依据。

Design of Low-speed Direct-drive External Rotor Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors have the characteristics of high torque density and high power factor and the increase in the number of pole pairs will not reduce the power factor, but the existence of cogging torque affects the stability of the output torque. In this paper, a 72-slot 60-pole 400kW direct-drive external rotor permanent magnet synchronous motor is designed. The two-dimensional finite element simulation model established by ANSYS Maxwell is used to analyze the no-load back EMF, cogging torque, air gap magnetic field and synchronous inductance, The rationality of the motor structure and parameters is verified and the focus is on the optimization of cogging torque and rotor loss. The method of optimizing stator cogging width and opening auxiliary slots is adopted to weaken the cogging torque, and the method of rotor pole segmentation is adopted to limit the path of eddy current to reduce rotor loss. The simulation results show that the designed motor can meet the performance indicators, which provides a basis for the optimization of motor design, cogging torque and rotor loss.