Mitigation Strategy for AC Side to Suppress CM Current Flowing on DC Cables of the Motor Drive System

The electromagnetic interference of the motor drive system has a great influence on the performance. For the motor drive systems, the interference of CM current is important cause of conducted emission. AC side of motor drive system is high voltage and load is large inductive motor, so the AC side has a big impact on the DC side in the process of rapid on-off devices. The CM EMI current paths at frequency 30 MHz are analyzed based on the distribution parameters of elements in current flowing circuit. The change of the CM EMI current will be analyzed through circuit and equation of the CM EMI current when the AC cable is added ferrite chokes or ferrite. The DC conducted emission electromagnetic interference suppression effect is obvious to add ferrite chokes or ferrite the AC cable in high frequency in the experiment, which is consistent with theoretical analysis. The results show that adding ferrite is more effective measure than adding ferrite choke to suppress the DC side conduction emission electromagnetic interference both in decreasing amplitude and larger frequency band.