A Novel Two Phase Nonisolated Full Bridge With Shared Primary Switches

In this paper, a new full bridge topology called the two-phase nonisolated full bridge (NFB) is introduced. The proposed two-phase NFB can handle the same power as two parallel NFB converters, but with less MOSFETs, better efficiency, and lower cost. To demonstrate the advantages of the new topology, two prototypes are built on a 12-layer 2-oz PCB board, one with four inductors, the other with three inductors. Two prototypes achieve 82.3% and 82% efficiency at 1-MHz full load (1 V/80 A), respectively. This is compared to 81.8% efficiency of the two paralleled NFB converters. At light load (1 V/10 A), a 4% efficiency improvement is achieved. Experimental results demonstrate that compared with two paralleled NFB converters, the two-phase NFB converter is able to achieve better efficiency with a simplified power train circuit and reduced cost.