DESIGN AND IMPLEMENTATION OF A DIGITALLY-CONTROLLED PHASE-SHIFT FULL-BRIDGE CONVERTER WITH OUTPUT SYNCHRONOUS RECTIFIER AND CURRENT DOUBLER

Shun-Chung Wang ； Li-Chung Shih ； Bo-Ruei Pen ； Yi-Hwa Liu

《技術學刊》 32卷4期 (2017/12) Pp. 283-297

摘要

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 density design that is applicable to medium or high power converters due to the capability of power switch with zero voltage switching (ZVS). The SR-type current doubler (CD) can reduce conduction losses, improve thermal distribution, allow for lower current profile, and possess the effect of ripple cancellation on the output filter capacitor. The conditions needed for achieving ZVS operation is first derived and discussed in detail. Deduction of the gating signals for SRs at different operating modes is done to prevent the drawing back current caused by the control mismatch between the primary switches and secondary SRs from destroying the circuit. Compromise selection of an adaptive dead-time is also provided to improve efficiency for all load outputs. The operating principle, design consideration, and gating signal generation are described exhaustively. A laboratory prototype is implemented and tested to validate the correctness and performance of the studied converter.

關鍵字

current doubler ； digital control ； phase-shifted full-bridge converter (PSFBC) ； zero voltage switching (ZVS)