变频驱动感应电机轴电流问题中端部杂散电容的解析计算

Analytical calculation of stray capacitance of motor end in bearing current problem of induction motor driven by frequency convertor

变频驱动系统产生的轴电流造成轴承电蚀损伤,对轴电流进行分析预测,需要对电机杂散电容进行准确提取。解析计算具有计算快速、关系清晰的优点,适合于电机优化设计中处理大量相似计算以获得轴电压抑制方案。电机端部电容计算非常关键且不可以忽略,但现有的解析方法不能准确计算这部分电容。本文对鼠笼式感应电机端部进行合理简化,将端部区域划分为不同子域,分别求取各子域电容。建立了电机端部电容解析计算模型,将端部电容各个子域的解析计算结果与电机端部的有限元仿真结果、最后整体和实测结果比较,结果表明该方法可以较为准确地计算端部电容。

The bearing current generated by the variable frequency drive system causes electric corrosion damage of bearings. To analyze and predict the bearing current, it is necessary to accurately extract the value of stray capacitances of the motor. For the analytical calculation has the advantages of fast speed and clear relationship, it is suitable to deal with similar calculation in motor design to obtain the scheme of shaft voltage suppression. The existing analytical calculation cannot accurately obtain the end capacitance, which is critical in the capacitance calculation. In this paper, the motor end is reasonably simplified. The end area was divided into different subdomains, and the capacitance of each subdomain was calculated respectively. The analytical calculation model of motor end capacitance was established. The analytical calculation results of each sub-domain of the end capacitance were compared with the finite element simulation results of the motor end, and finally the whole and measured results were compared. The results show that this method can calculate the end capacitance accurately.