Suppression of Conducted Emission Noise in Electric Vehicle Charger with Passive EMI Filter

The EV battery charger system has the potential to generate significant EMI noise due to the fast-switching process of the AC-DC converter.It may cause interferences to the operation of other electronic devices nearby.In this paper, a passive Pi-based filter was developed to mitigate EMI and to reduce conducted emission (CE) noise on an EV charger system.The filter design process was guided by a systematic approach where firstly the differential mode (DM) and common mode (CM) components of conducted emissions were separated and measured.After that, the required level of attenuation was calculated according to the standard's limits.Based on the needed attenuation level, the DM and CM filter component values were calculated and simulated.After obtaining the optimized component values, the filter was implemented.Measurement results showed that the proposed Pi filter effectively suppresses the EMI noise up to 43.40 dBV/m resulting in the CE noise level met the EMC standard.