Analysis of the Active-Clamped Soft-Switched Forward Converter without Output Filter

This paper analyzes an active-clamped soft-switched forward converter without output filter. Differently from the topology presented in [G.Spiazzi et al., (2002)], the transformer reset is obtained by using an active clamp subcircuit instead of a lossless passive snubber. This solution avoids the use of a second inductor and auxiliary diodes and allows a better exploitation of the converter components, since now both the main and the auxiliary switch turn on at zero voltage and zero current, and they turn off at zero voltage by using a loss-less capacitor. The resulting topology is practically identical to that of an active-clamped flyback converter, except for the reversed transformer secondary side polarity. Thus, in addition to the converter analysis, the paper presents a comparison between the proposed converter and the active-clamped flyback converter, by testing two prototypes rated for 48 W output power.