Zero-voltage switching full-bridge DC/DC converter with parallel-connected output and without output inductor

摘要

This study presents a soft-switching converter without output inductor. The features of the proposed converter are zero-voltage switching (ZVS) for all power switches, load current sharing and high circuit efficiency. Full-bridge converter with phase-shift pulse-width modulation (PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active switches can be turned on at ZVS during the transition interval. Thus, the switching losses of power MOSFETs are reduced. The voltage stress of power switches is clamped to DC bus voltage. Four transformers are connected in series in the primary side. Each transformer can be operated as an inductor to smooth the output current or a transformer to achieve electric isolation and power transfer from input side to output side. Therefore no output inductor is needed in the secondary side. Two centre-tapped rectifiers connected in parallel are used in the secondary side to achieve load current sharing. Finally, experiments based on a 960 W (48 V/20 A) laboratory prototype are provided to demonstrate the performance of proposed converter.