Evaluation of Active Common Mode Filter Utilization for Size Optimization of a 20 kW Power Factor Correction

This paper presents active filtering of common mode (CM) noise for size reduction of an electromagnetic interference (EMI) filter used in a high frequency 20 kW three-phase power factor correction (PFC). Increasing the switching frequency helps reducing the size of reactive components; however, higher switching frequency leads to higher amplitude of harmonics in the EMI range (>150kHz). Adding an auxiliary winding to the CM inductor is studied in depth to achieve active CM filtering which shows more attenuation of the CM current, and consequently size reduction of the EMI filter. Furthermore, in this paper, CM noise is generalized by introducing the parasitic capacitors of the converter into the modeling. The model is verified by a 20 kW three-phase PFC experimental setup. Finally, the efficiency and effectiveness of the designed active CM filter is verified by a comprehensive simulation.