Introduction

Similar to other bridgeless topologies, totem-pole PFC generates significant Common-mode noise, especially around the zero crossings of the input line voltage. The issue arises due to the redistribution of charge in the Y-capacitors at the input and output of the PFC as the AC source polarity transitions from negative to positive and vice versa, resulting in short but very large currents flowing in the Common-mode loop formed via the neutral and the output bus ground through these Y-capacitors.

The technical brief proposes managing the rate of charge distribution in the Y-capacitors as a solution to suppress noise.