A simple low-cost common mode active EMI filter using a push-pull amplifier

A simple low-cost active EMI filter (AEF) without transformers is proposed. The equivalent circuit model of the proposed AEF is built, and a block diagram is extracted for efficient feedback analysis. The feedback loop gain and the performance of the AEF are calculated and validated by comparison with SPICE simulations. The proposed AEF enlarges the effective value of Y-capacitors. The AEF is manufactured for the application of a 2.2kW resonant inverter, and the performance is demonstrated by measurements of the conducted emissions.