交流电机高频轴电流集中参数模型与分布参数模型的对比研究

Comparative Research on the Lumped Parameter Model and the Distributed Parameter Model in High Frequency Bearing Current Problem of AC Motors

PWM变频调速技术的广泛应用给电机带来了高频轴电流的问题,引起轴承早期失效,严重危害交流电机的安全、可靠运行。电机高频等效模型的准确性对轴电流的预测有直接影响。本文首先通过解析和仿真方法对电机集中参数模型和三相分布参数模型进行对比分析,分析表明,两种模型的轴电流幅值相近,但振荡频率不同;其次研究了沿轴向分段的电机高频分布参数模型对轴电流预测的影响,研究表明分段数会影响轴电流幅值,合理的分段数与电机的尺寸和轴电流频率范围相关;最后将分析结果与实验结果进行对比,结果显示通过分段分布参数模型得到的轴电流幅值比集中参数模型更接近于实测值。

PWM(pulse width modulation)frequency conversion technology is widely used in motors speed regulation and control system.However it also brings bearing currents problems,which seriously effects the safety and reliability of AC motors.The equivalent circuit of bearing current is a critical factor to accurately predict the current.This paper compares the lumped parameter equivalent circuit and the distributed parameter circuit of baring currents.The results show that the lumped parameter circuit and the three-phase distribution circuit have no difference on bearing current amplitude,but which affects the frequency of the current.Then the influence of the distributed parameter circuit along the shaft is investigated.The segment number has influence on the results.The experiments show that the simulation results of the distributed parameter model are closer to that of the test than that of the lumped parameter model.