Design and Implementation of a Digitally-Controlled Phase-Shift Full-Bridge Converter with Output Synchronous Rectifier and Current Doubler

This paper presents a digitally-controlled phase-shifted full-bridge converter(PSFBC) with output synchronous rectifier (SR)-type current doubler.The proposed PSFBC can achieve a high efficiency and high power densitydesign that is applicable to medium or high power converters due to the capabilityof power switch with zero voltage switching (ZVS). The SR-typecurrent doubler (CD) can reduce conduction losses, improve thermal distribution,allow for lower current profile, and possess the effect of ripple cancellationon the output filter capacitor. The conditions needed for achievingZVS operation is first derived and discussed in detail. Deduction of the gatingsignals for SRs at different operating modes is done to prevent the drawingback current caused by the control mismatch between the primary switchesand secondary SRs from destroying the circuit. Compromise selection of anadaptive dead-time is also provided to improve efficiency for all load outputs.The operating principle, design consideration, and gating signal generation aredescribed exhaustively. A laboratory prototype is implemented and tested tovalidate the correctness and performance of the studied converter.