Multi-input bidirectional DC-DC converter combining DC-link and magnetic-coupling for fuel cell systems

This paper presents a new multi-input bidirectional dc-dc converter which connects a fuel cell, storage and load by a combination of a dc-link and magnetic-coupling. A boost-dual-half-bridge and a bidirectional direct-connected switching cell are used. The topology is simple and only needs six power switches. The load and the sources are galvanically isolated. Furthermore, the proposed converter draws/injects smooth current from the fuel cell and the supercapacitor. The system is suitable for medium-power applications where simple topology, autonomous operation, compact packaging, and low cost are required. Different control schemes to manage power flow are proposed and compared. Simulation and experimental results that verify the effectiveness of the topology and its control scheme are presented. Moreover, it is shown that the idea of combining the dc-link and magnetic-coupling can be further developed to a general topology for multi-port bidirectional dc-dc converters.