Passive Cancellation Method for Common-Mode Noise Based on a Nonlinear Model

AC-DC converters almost always require common-mode (CM) filters to restrict conducting their electromagnetic interference (EMI) emissions to the power grid and ensure compliance with EMI certification requirements. These CM filters, which are based on the well-known LC lowpass filter, are typically bulky and expensive. Hence, a method for passive CM current cancellation using a nonlinear model is proposed herein. This method is entirely composed of passive components and offers advantages in terms of cost and system reliability. Compared to conventional passive LC filters, the number of magnetic components remains unchanged. This study proposes the derivation of a nonlinear model to estimate the filter performance using measured data from an actual CM choke; however, the proposed method does not require the mathematical model of a CM choke.