Abstract： To improve the accuracy and reliability of flywheel energy storage system and reduce the effects of torque ripple and suspension force ripple on system operation, the relationships of the suspension force and torque of bearingless outer rotor asynchronous motor with motor structure parameters were analyzed. The general methods were proposed to minimize torque ripple and suspension force ripple. Based on the working principle of bearingless asynchronous motor with outer rotor, the mathematic model of motor was deduced. According to the traditional asynchronous motor design method, a 0.5 kW bearingless asynchronous motor with outer rotor was designed by dichotomy approach with two polepair torque winding and one polepair radial suspension winding. The distribution of magnetic field was simulated by FEM, and the relationship among radial suspension force, torque and winding current was determined. The effects of magnetic saturation and size of airgap on radial suspension force were also investigated with consideration of the effects of slot ratio and stator pole arc coefficient. The results show that with respective torque windings and radial suspension force windings rated currents of 2.5 A and 2.0 A, the rotor of prototype motor can be stably suspended with torque of 1 N·m and rotor radial suspension force of 105 N.
孙宇新, 王浩, 杜怿. 无轴承外转子异步电动机的设计及有限元分析[J]. 江苏大学学报（自然科学版）, 2016, 37(3): 321-326.
SUN Yu-Xin, WANG Hao, DU Yi. Design and finite element analysis of bearingless outer rotor asynchronous motor[J]. Journal of Jiangsu University(Natural Science Eidtion)
, 2016, 37(3): 321-326.
2016, Vol. 37 
