轴电流问题中轴承模型的探究及等效电阻计算

Research on Bearing Model of Bearing Current Analysis and Calculation of Equivalent Resistance

随着PWM变频调控技术在电机驱动中的广泛应用,轴电流问题越来越突出。在分析和预测轴电流时最为复杂的问题之一是轴承等效电气模型的建立,以往模型中将轴承等效为简单的电容和电阻串、并联的组合,但由该模型得到的轴承击穿波形与实际测得的击穿波形并不相符。从轴承击穿电压、电流波形出发,结合轴承实际结构,提出一种改进的轴承等效模型。该模型中轴承等效击穿电阻为可变电阻,并结合电弧击穿理论确定了可变电阻的计算方法。对基于新模型的轴承等效电路进行仿真,并与试验测得的击穿波形图对比。结果表明,与恒定电阻模型相比,提出的模型能更好地模拟轴承击穿和恢复的过渡过程。

With the wide application of pulse width modulation(PWM) technology in motor drive, the bearing current problem becomes more and more prominent. The bearing equivalent model is one of the most complicated problems in analyzing bearing currents. Usually a simple capacitor, resistor series or parallel circuit is used to model the bearing breakdown process, but it is not consistent with the experiment result. An improved equivalent bearing model is proposed, which is derived from the structure of the bearing and the waveform of the bearing breakdown. The equivalent breakdown resistance of the bearing is variable, which is determined through the arc breakdown theory. Comparing the simulation waveforms with the experiment waveforms, the proposed equivalent bearing model is more accurate than the previous constant resistant model.