Passive filter topology study of single-phase ac-dc converters for DC nanogrid applications

This paper presents an exhaustive study of the topology of passive components based on a two-stage single-phase (1Φ) ac-dc converter for a DC nanogrid application. The design of passive components is discussed by considering the aspects of power density, power quality, conducted EMI, dc small-signal interaction, grounding scheme and the common-mode (CM) voltage level. The first-stage ac differential-mode (DM) capacitors are utilized to clamp the dc-side CM voltage level, thereby reducing the CM switching harmonics by more than 30 dB. This article presents the the whole converter system structure in terms of the existing residence distribution system in North America, and presents design considerations and experimental results.