交流电机轴电流高频模型精确建模  

Accurate Modeling of High Frequency Bearing Currents in AC Motors

作　　者：刘瑞芳[1] 李知浩 李照林 张亮亮 李伟力[1] Liu Ruifang;Li Zhihao;Li Zhaolin;Zhang Liangliang;Li Weili(School of Electric Engineering Beijing Jiaotong University,Beijing,100044,China;State Grid Beijing Shunyi Electric Power Supply Company,Beijing,101300,China;Jing-Jin Electric Technologies Co.Ltd,Beijing,100015,China)

机构地区：[1]北京交通大学电气工程学院,北京100044 [2]国网北京顺义供电公司,北京101300 [3]精进电动科技股份有限公司,北京100015

出　　处：《电工技术学报》2024年第22期7019-7029,共11页Transactions of China Electrotechnical Society

基　　金：北京市自然科学基金(3222055);2021年高功率高效电驱动总成系统开发及产业化项目(TC210H02Q)资助。

摘　　要：在变频电机驱动系统中,变频器输出的高频共模电压会在电机内部感应出轴电压和轴电流,继而引发轴承电腐蚀,危害系统运行的安全性和可靠性。建立精确的轴电流高频模型对于预测轴承电腐蚀风险、制定维护计划和设计抑制方案具有重要意义。该文对现有的轴电流高频模型的误差来源和范围进行了分析,指出了现有方法在阻抗特性中频部分与实测曲线存在不匹配的问题。为了克服这一缺陷,提出了一种改进的轴电流高频模型,以及相应的参数提取方法。该方法考虑了电机在不同频率下的谐振机理和等效电路,利用特征频率点阻抗值求解参数,以确保模型充分还原各频段的阻抗特性。针对一台190 kW异步电机,分别采用改进模型和现有模型进行对比。结果表明,改进模型更接近电机实际端口阻抗特性,验证了所提方法的准确性。The regulation technology for PWM variable frequency speed significantly enhances the dynamic performance of the motor drive system.However,it also introduces adverse effects like bearing electric corrosion.The high-frequency common-mode voltage output by the frequency converter induces bearing voltage and bearing currents inside the motor,leading to bearing electric corrosion and reducing the bearings'lifespan.The high-frequency model of motor bearing current can accurately simulate and predict the bearing current.In practical applications,it helps to identify key parameters and influencing factors of the bearing current,evaluate potential bearing electric corrosion risks,develop predictive maintenance plans,and guide the design of suppression schemes.Due to the advantages of simple calculation,high precision,and clear physical meaning,the establishing method of the high-frequency model of bearing currents based on the impedance curve has garnered wide attention.This paper analyzes the error sources and ranges of three existing high-frequency models,pointing out the poor fitting performance of existing models in the mid-frequency range.A high-frequency bearing currents model with high accuracy is proposed based on the distributed parameter model.Then,the impedance analyzer is used to test a 190 kW motor,and the port impedance characteristic curves are obtained.The resonance mechanism and equivalent circuit of the motor under low frequency,medium frequency,and high frequency are analyzed.The characteristic points at different frequencies are used to solve the parameters to consider the influence of each frequency band.Finally,multiple simulation circuits are constructed to verify the new model’s accuracy.The root mean square error of the port impedance at the key frequency points is taken as the evaluation index.Compared with the existing methods,the new method reduces the impedance error between the stator winding and the frame by more than 50%in the frequency range 100 kHz~10 MHz,which has higher accuracy.In

关 键 词：交流电机 轴电流 高频模型 阻抗特性 

分 类 号：TM315[电气工程—电机]