Non-Isolated DC-DC Converters With Low Common-Mode Noise by Using Split-Winding Configuration

Abstract

The common-mode (CM) noise in nonisolated dc-dc converters is mainly caused by the displacement current through the high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> node in the circuit and the associated parasitic capacitance, and it may cause electromagnetic interference (EMI) to the surrounding equipments. To reduce the original CM noise and shrink the EMI filter size of non-isolated dc-dc converters, CM noise cancellation methods have been proposed, including the symmetry circuit, balancing technique, passive cancellation and CM voltage cancellation. In these methods, additional components or windings are required for reducing the CM noise. In this article, a new CM noise cancellation method in non-isolated dc–dc converters is proposed by adopting a split-winding configuration. Compared to the existing CM noise cancellation methods which require additional components, the proposed method in the buck, boost and single-ended primary-inductor converter (SEPIC) converters which runs in voltage step-up mode has the identical volume as their conventional circuit configurations. The proposed method is verified for a buck converter by experiment.