PWM变频驱动电机轴电压与轴电流的测试方法

Measurement Methods of Bearing Voltage and Bearing Currents in Motors Fed by PWM Inverter

PWM变频器的广泛应用大大改善了电机调速性能,但是,由于PWM变频器共模电压在电机内部耦合电容作用下,形成轴电压和轴电流,会引起轴承早期失效危及系统安全运行。轴电流问题的研究包括对轴电流的分析、预测和抑制。然而这些过程需要轴电压和轴电流的准确测量进行验证和比对分析。设计合理而有效的测量装置和测量方法是非常重要的一环。在分析轴电流产生机理的基础上,对现有的各种轴电流测量方法和轴承阻抗特性测试方法进行介绍,总结对比这几种方法的优缺点,为轴电流的测试平台的新设计提供参考。

PWM inverter is widely applied in industry, which brings better motor speed control performance. However, the common mode voltage of PWM inverter drive system will induce bearing voltage and baring current in the motor under the influence of the coupled capacitance of the motor, which cause reduction of the bearing lifetime and threaten of the safety of driving system. The research of bearing current problems includes analysis, prediction and suppression. These processes require the bearing voltage and bearing current to be accurately measured. Then, it plays a significant part to design the reasonable and effective measuring devices and measuring methods. In this paper, after analyzing the generating mechanism of bearing current, the various existing bearing current measuring methods and bearing impedance characteristic test methods are introduced. The advantages and disadvantages of these methods are summarized and compared. It provides a reference for designing new test platform to measure bearing current.