Natural commutation method for a low-voltage high-current input DC-DC converter

This paper presents a high-efficiency isolated boost DC-DC converter with low-voltage high-current input based on a new principle of natural commutation. The proposed circuit comprises interleaved full-bridge DC-AC inverters on primary and parallel-connected bridge-rectifiers on the secondary side of a high-frequency isolation transformer. Commutation between inverters is established by the voltage across series capacitors inserted in the output of DC-AC inverters. Zero-current-switching (ZCS) of the load current is realized through commutation using no resonance operations. The operation principle, characteristics and design method are analyzed and presented herein. The feasibility of the proposed DC-DC converter is verified from its high efficiency of greater than 97% over the wide range of 20-100% of the rated load with input conditions of 25 V, 50 A, and approximate output of 350 V, 1.2 kW.