【作者】 王世怀；

【导师】 段志善； 熊万里；

【作者基本信息】 西安建筑科技大学 ， 机械电子工程， 2004， 硕士

【摘要】 现代变流技术为工业控制提供了—种完美的方案，尤其是PWM变频器的高频率开关大大提高了交流电动机的调速性能。然而，随着近些年来现代变流技术的推广，其负面影响也越来越突出，一个重要的方面就是对润滑界面造成的电磁损伤问题相当严重。由于PWM变频器的三相输出电压在瞬间并不对称，所以导致电机三相定子绕组的电压矢量和不为零，从而出现共模电压。由于变频器的高开关频率，导致共模电压具有很高的电压变化率，其dv／dt可以达到6000V／us以上，在如此高的电压变化率下，润滑油膜充当了电容的作用对转轴进行充电，形成轴电压。当电压超过了润滑油膜所能承受的电压时，油膜被击穿出现很大的放电电流，甚至出现电火花，导致润滑界面的破坏。这种破坏经常出现在电机的轴承或者是与电机主轴相连的齿轮齿面上，使轴承或齿轮的寿命大大缩短。 本文主要以电机轴承为研究对象，对现代变流技术导致的润滑界面电磁损伤现象进行研究。对轴电压的和轴电流的形式进行了全面的介绍；详细研究了PWM变频器供电下轴电压的产生机理，建立了PWM变频器供电下系统的共模电压模型，通过这个模型来分析PWM变频器供电下润滑界面破坏的机理，同时，进行计算机仿真；建立实验台，对PWM变频器供电下交流电动机的轴电压进行采样和分析；通过仿真结果与实验采样结果的比较来验证模型的正确性；分析了影响轴电压和轴承电流的几种因素，通过轴承电流密度来计算轴承的寿命，确立了润滑界面电磁损伤的定量刻划指标；对润滑界面电磁损伤的应对策略和解决方案进行研究。更多还原

【Abstract】 Modern power inverters provide the industrial control industry with significant advantages, especially the faster switching devices of pulsewidth modulated(PWM) inverters have increased drive performance. However, while the modem power inverters were used more and more widely, its disadvantages turn to be more and more serious, one of which is lubricate interface electromagnetism damage. Because the output voltage of PWM inverter is dissymmetry instantly, the common mode voltage appears as a result. The common mode voltage has high abrupt transformation rate because of the fast switching devices, whose dv/dt can exceed 6000 V/us . Under so high dv/dt, the oil film acts as a capacitor and provides a charging mechanism for rotor shaft voltage buildup. When the rotor to ground voltage is exceed the critical oil film threshold voltage, the oil film breakdown induce a large current, and even appear electric discharge machining (EDM) current. Therefore, the lubricate interface is damaged. This damage was often occurred in the surface of bearing or gear that connected with motor shaft, induce the bearing or gear premature.This paper mainly study electromagnetism damage problem on the bearing lubricate interface induced by modern power inverter. Investigate the different forms of rotor to ground voltage and bearing currents. Examines the mechanism and electrical characteristics of bearing, and converts them into common mode voltage models in PWM inverter control system. Abstract and analysis the signal of rotor to ground voltage via experiment. Compare the result of simulation and signal abstracted from experiment in order to show the correctness of model. Study the factors which can influence the rotor to ground voltage and bearing currents. Give a ways to estimate the electrical life of a mechanical bearing by building the relationship between the current density and bearing life. Establish the quantificational method to measure the magnitude of lubricate interface electromagnetism damage. Search the possible techniques to eliminate or mitigate lubricate interface electromagnetism damage problem.更多还原