Reversible DC/DC Converter as interface between Low and Medium Voltage DC Networks

This paper introduces an isolated reversible DC/DC converter with a particular topology, which benefits from both the Neutral Point Clamped (NPC) structure and the series-parallel connection of converters. The key property of the proposed topology is the output voltage elevation above the blocking capabilities of each switch, without taking to a delicate synchronization of series-connected semiconductors. The converter is composed by two identical cells, each containing a full bridge, a medium frequency transformer and an NPC converter, connected in parallel at the input and series at the output. The operation principle of each cell, into which a trapezoidal modulation was implemented, is similar to a Dual Active Bridge (DAB). Simulation and experimental results verify the proposed topology, its control and start-up strategy.