Active-clamping forward converter with non-linear step-down conversion

Abstract

This study proposes a forward converter with non-linear step-down conversion ratio. In comparison with traditional forward converters, it has a higher duty utilisation ratio. Furthermore, the two output inductors can equally divide the load current, and therefore the current stress of inductors and output diodes can be reduced. Thus, the proposed converter is suitable for high step-down applications. On the primary side, active-clamp control can nullify the voltage spike of main switch while also achieving zero voltage switching operation of the main switch and auxiliary switch, hence the switching loss can be reduced. Detailed analysis and design of the proposed converter are described. Experimental results are recorded for a prototype converter with an AC input voltage ranging from 90 to 264 V, an output voltage of 12 V, and an output power of 240 W.