1-MHz Self-Driven ZVS Full-Bridge Converter for 48-V Power Pod and DC/DC Brick

Abstract

In this paper, a self-driven zero-voltage-switching (ZVS) full-bridge converter is proposed. With the proposed self-driven scheme, the combination of the ZVS technique and Self-driven technique recycles the gate driving energy by making use of the input capacitor of the secondary side synchronous rectifier (SR) as the snubber capacitor of the primary side switches. Compared with the external driver, the proposed converter can save driving loss and synchronous rectifier body diode conduction loss. Additionally, compared with the existed level-shifted self-driven scheme for bridge-type symmetrical topologies, its gate signal is very clean and suitable for high-frequency applications. A 1-MHz, 1.2-V/70-A prototype is built to verify the analysis. Experimental results show that it can achieve 81.7% efficiency. And there is an efficiency improvement of 4.7% over conventional phase-shifted full-bridge converter with an external driver.