A General-Purpose Three-Phase DC-DC Converter Building Block for Fuel Cell Applications

Multiphase dc-dc converters allow current sharing among phases and high-frequency ripple cancellation and are very desirable for low-voltage high-power fuel cell applications. In this paper, a versatile three-phase dc-dc converter circuit as a building block is proposed for different output voltage levels including non-isolated 48 V for telecom and isolated 400 V for subsequent stage dc-ac inverter applications. For either type of application, the proposed three-phase converter circuit is controlled by the same complementary gating control that allows synchronous rectification for the non-isolated version and zero- voltage soft switching for the isolated version. Two sets of 5-kW converters have been built and tested with a fuel cell simulator. Experimental results are given to show the superiority of the efficiency performance in two different applications.