Active clamped ZVS forward converter with soft-switched synchronous rectifier for high efficiency, low output voltage applications

The analysis, design, and implementation of an active clamped ZVS forward converter equipped with a soft-switched synchronous rectifier (ACFC-SR), proposed for high-efficiency low output voltage DC-DC converter applications, is presented. The converter efficiency is maximised due to soft switching of the main, active clamp, synchronous rectifier, and freewheeling MOSFET switches. The operating principles of the ACFC-SR are analysed in detail, and the converter performance is compared with that of alternative forward converter schemes employed in low output voltage DC-DC converters, in view of their power conversion efficiency. Experimental results are presented for a 50 W ACFC-SR converter with a DC input voltage of 48 V, an output voltage of 5 V, and operating at a switching frequency of 120 kHz. In general, good agreement is observed between the theoretical and experimental results.