Modeling and analysis of hybrid differential mode filters for AC/DC converters to suppress current ripples and EMI

This paper proposes a hybrid DM Electromagnetic Interference (EMI) input filter model for AC-DC converters. After briefly reviewing DM EMI noise model for AC-DC converters, a closed loop filter model is developed. Based on the closed loop model, the open loop characteristics required for active filter's stable operation is determined. The constraints and requirements for the efficient implementation of the active filter are identified. High pass fitters are integrated with the active filter to avoid line frequency current cancellation. Compensation design technique is proposed to achieve a particular gain requirement and ensure stability for the active filter. The proposed model has been analyzed theoretically and also implemented in hardware. The developed technique was verified in experiments.