基于电磁场数值计算的变频供电感应电机耦合电容与轴电压的分析  

Modeling of Coupled Capacitances and Bearing Voltage in Induction Motors Fed by Inverters Based on Numerical Calculation of Electromagnetic Field

作　　者：刘瑞芳[1] 李俊峰[1] 桑秉谦 曹君慈[1] 

机构地区：[1]北京交通大学电气工程学院,北京100044

出　　处：《电工技术学报》2015年第14期161-169,共9页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金(51107004);中央高校基本科研业务费专项资金(2013JBM016)资助项目

摘　　要：PWM变频供电驱动电机系统共模电压在电机耦合电容作用下会在轴承上产生轴电压和轴电流,影响电机的安全运行。对电机耦合电容的准确计算有助于合理预测轴电压的大小。本文在分析驱动系统共模模型基础上,建立了电机耦合电容计算的有限元分析模型,求得电容参数。比较了二维和三维有限元下电容计算结果,指出绕组端部对定子绕组与转子间耦合电容Cwr有较大的影响,计及端部时得到的电容Cwr更接近实测结果。采用定子绕组电磁散线计算模型可以大大提高定子绕组与铁心间电容Cwf计算精度。在不同电机端部结构参数下进行分析计算,发现定子绕组端部伸直部分长度和鼠笼端环的轴向长度是影响电容Cwr的两个主要参数。对变频供电下的感应电动机进行三维瞬态电场有限元分析,表明轴电压为共模电压的镜像,证明了电容分析模型是有效的。The common mode voltage of PWM inverter drive system will induce bearing voltage and bearing current in the motor under the influence of the coupled capacitance of the motor. Accurate calculation of the coupled capacitance of the motor is important to forecast the bearing voltage. After analyzing the common mode circuit model of the system, the 2D and 3D finite element models of the motor are established respectively. The results show that the end part of winding is a key factor to the stator winding to rotor capacitance Cwr. The calculation considering the end part of winding in 3D analysis is more accurate than which in 2D analysis. It is concluded that the length of extended straight part of stator winding and the thickness of squirrel-cage ring in axial direction are two main factors which can affect Cwr. The 3D transient electric field finite element calculation is applied on an induction motor fed by inverter. The result shows that bearing voltage mirrors the common mode voltage, which verifies the effectiveness of the analysis model.

关 键 词：PWM逆变器 感应电机 耦合电容 绕组端部 轴电压 

分 类 号：TM315[电气工程—电机]