Analysis and design of two-switch flyback converter with double passive lossless snubber

A double passive lossless snubber (DPLS) is applied to a pulse width modulation two-switch flyback converter (TSFC). The DPLS, which has two capacitors, two inductors, and four diodes, has achieved zero voltage turn off and zero current (ZC) turn on for power switches without high voltage and current stresses; ZC turn on and ZC turn off for a rectifier diode without a reverse recovery problem. In this study, the steady-state operating modes of TSFC-DPLS are analysed and the proposed converter design procedure to operate in the continuous conduction mode is taken. To validate the theoretical analysis, a 240W prototype TSFC-DPLS under an 85-135V(rms) input, 24V(DC) output, and 300kHz is implemented. Finally, by utilising the experimental results, the soft switching conditions under wide input voltage and output load ranges are discussed.