High gain and efficient integrated flyback-Sepic DC-DC converter with leakage energy recovery mechanism

A Sepic converter with both of its inductors replaced by the Flyback transformer has been proposed here. Outputs of the two Flyback sub-parts are connected in series along with the normal Sepic converter output to result in a high positive overall output voltage. The Sepic converter portion acts as a passive clamp to both the Flyback converters. During the switch turn-off instant, the leakage inductor current of the Flyback transformers doesn't get interrupted. Hence, no spike can appear in the drain to source voltage of the switch. Due to the presence of the two transformers as the energy storing elements, the converter can be used for applications requiring higher power handling compared to the conventional Flyback converters. The proposed circuit has got the features like less leakage inductance transformers, less rating devices, low component count and provide high overall gain at high efficiency. In the subsequent sections of the paper, the working principle of the converter has been explained and validated through open loop simulations were done using Matlab-Simulink. The introduction part highlights the advantages of the proposed circuit over the other circuits used for similar purposes. Considering the effect of some of the parasitic elements of the circuit, the converter has been analyzed in detail for the steady state operating condition.