Implementation of a MOSFET-based active differential mode EMI filter in DC/DC converter

A switching mode power supply will easily cause serious electro-magnetic interference (EMI) because of the high frequency operation of the power devices. The traditional passive EMI filter (PEF) is bulky and also not efficient in low frequency range. A differential mode active EMI filter (AEF) for DC/DC converter is proposed in this paper. With the analysis and modeling of the full bridge DC/DC converter, a voltage feedback differential mode active EMI filter based on MOSFET is established. The experimental result shows that this AEF has a good differential mode noise attenuation quality.