Functional Features of Isolated AC/DC Converter Interface in Future Low-Voltage DC Microgrids

In order to decouple dynamics of low-voltage DC microgrids and the AC utility grid and apply specific grounding configurations, it is required that the AC/DC converter interface features transformer galvanic isolation. This paper proposes a simple, bidirectional, two-stage converter topology with an active front-end AC/DC stage followed by an isolated, resonant DC/DC converter, operated as a DC transformer. The isolated AC/DC interface features droop control implemented using a minimized set of measurements and feedback loops. Theoretical considerations are backed up with simulation results for different power levels, justifying the feasibility of the proposed converter topology and the droop control strategy for the given purpose.