轴向磁轴承涡流损耗分析

Analysis on Eddy Current Loss for Axial Magnetic Bearings

针对实心铁芯结构的轴向磁轴承推力盘沿轴向高频振动时产生的铁芯涡流损耗,提出了一种基于有效磁阻法和等效磁路法的涡流损耗磁路计算模型,将磁通路径上的铁芯涡流以有效磁阻的形式等效,并给出了动态气隙磁通及电磁力的解析解。对磁轴承解析模型与不考虑和考虑漏磁、磁化曲线饱和及边缘效应的有限元分析结果进行了对比分析。结果表明:涡流磁阻的等效合理;解析模型计算的损耗比有限元模型大,且在高频段的误差明显。解析模型能够形象直观地表示磁轴承的电磁力和涡流损耗,且模型简单,参数易于修改,适用于低功耗磁轴承结构的参数选定及优化设计。

For solid core of axial magnetic bearings, a magnetic circuit model for eddy current loss is presented based on the effective reluctance method and the equivalent magnetic circuit method, when the speed of vibration along the axis is high. The effect reluctance into the flux path is introduced. Then the analytical model of flux and force are obtained with the equivalent magnetic circuit method. In addition, an analysis of the eddy current is introduced with transience finite element method, and the results are compared with the analytical model. The results show that the eddy current loss derived from the analytical model agree well with the FEM model results without leakage, flux saturation and fringing effects. Therefore, the equivalent eddy current reluctance is reasonable. The results of FEM model which considering leakage, flux saturation and fringing effects, show that the magnetic flux leakage weaken the influence of the airgap vibration to the magnetic field, that results in the eddy current loss derived from the analytical model is larger than the FEM, and the error is great at high frequency band. However, analytical model is able to visually represent the electromagnetic force and the eddy current loss. It can be used for parameter selection and optimization of design for low -power magnetic bearing, since the model is simple and parameter is easy to modify.