1 MHz self-driven ZVS full-bridge converter for 48 V power pods

In this paper, a self-driven zero-voltage-switching (ZVS) full-bridge converter is proposed. The control strategy is similar to an asymmetrical control for each leg. Analysis shows that it can still achieve ZVS for the primary switches. Furthermore, this control strategy is very convenient to realize self-driven. A new driver scheme is proposed, which can solve the transient response problem of the conventional driver scheme. Compared with the external driver, the self-driven can save driver loss and synchronous rectifier body diode conduction loss. Additionally, compared with the level-shifted self-driven concept 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.