An Efficient Active Common Mode Filter: Comparison of Feedback and Feedforward Based Methods for a 20 KW 3-phase Inverter

In this paper, to reach more attenuation for common mode (CM) voltage and consequently reduce the electromagnetic interference (EMI) emission, different active CM filters are compared for a selected case study. Whether the current or voltage are measured, and which kind of processed signals are added to the circuit, different composition of active CM filters with feedback or feedforward controls can be introduced. To efficiently select the optimum active filter configuration, the CM filter transfer function for each configuration is analyticallyextracted and studied. Therefore, the attenuation of each configuration is calculated and compared. To verify the analysis and the models, a simulation model including the model of the line impedance stabilization network (LISN) is made for a 20 kW three-phase inverter.