A novel three-phase high power current-fed DC/DC converter with active clamp for fuel cells

In this paper, a new three-phase high power current-fed dc/dc converter with active clamp is proposed. A three phase DC-DC converter with zero voltage switching (ZVS) with high frequency transformer isolation is shown. A single common active clamp branch is used to limit transient voltage across the three-phase full bridge and to realize zero-voltage switching (ZVS) in all switches by using the energy stored in the transformer leakage inductance. The proposed approach has the following advantages : an increase (by a factor of three) of input current and output voltage chopping frequencies; lower rms current through the inverter switches with higher power transfer capability; reduction in size of reactive (filter) components; better transformer utilization. The proposed converter is suitable for higher power fuel cell dc sources with low voltage outputs. The paper details the analysis, simulation and hardware implementation of the proposed system. Finally experimental results obtained on a 500W prototype demonstrates the feasibility of the proposed scheme.