变频器共模电流对敏感数据线干扰的实验研究

Experimental Research on Common-mode Interference on Sensitive Cable in a Motor Drive System

变频器在运行过程中输出电缆上会产生共模电流,若数据通讯线离其较近,便会受到共模电流耦合,严重时会干扰到通讯线所连接处理器正常工作。这里对变频器输出线缆共模干扰进行测试,并阐述了变频器输出线缆共模电流的产生机理和特性。以变频器与可编程逻辑控制器(PLC)通讯为例,通过实验测试,定量比较了不同工作情况下通讯线上共模电流时域和频域特性,提出了用误码率来评估不同共模电流对通讯性能产生的干扰影响程度。研究表明通讯线所耦合的共模电流低于一定强度时,便不会干扰变频器与PLC的正常通讯。

The inverter generates common-mode current on its output cable when in operation.If the cable is close to sensitive device, it will affect the normal operation of the device by coupling of common-mode noise.The common- mode current of the output cable of an inverter has been measured, and the characteristics and generation mechanism of the common-mode current has been analyzed.In the case of communication between the inverter and a prog- rammable logic controller（PLC）, the time-domain and frequency-domain characteristics of the common-mode current of communication cable under different operating conditions are compared by experiment.It employes error rate to evalu- ate the impact of different common-mode interference on communication cable.h has been demonstrated that when the coupled common-mode current on communication cable is lower than a certain value, the normal communication be- tween the PLC and the inverter will not be interfered.