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This study presents a novel single-switch high step-up dc-dc converter employing a quasi-resonant operation with high efficiency and low ripple continuous input current characteristics. In order to achieve a high voltage gain, a combination of coupled inductor and switched capacitor techniques is used in the proposed dc-dc converter. Moreover, utilising a series resonance capacitor with the leakage inductance of the coupled inductor leads to a resonant circuit. Subsequently, by employing a quasi-resonant operation, the switching loss of the proposed dc-dc converter has been reduced significantly. Operational analysis, mathematical derivation, component voltage and current ratings are well demonstrated in this study. Finally, the performance of the proposed circuit is evaluated through a 200 W laboratory prototype with 25 V input voltage and 400 V output voltage. The maximum efficiency achieved at full load is 96.4%.

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A single-input double-output dc-dc isolated high step-up dc-dc converter with soft-switching feature is presented in this study. The concept is to utilise quadrupler technique to reach high voltage gain without large duty cycle. Additionally, softswitching operation for all power switches and diodes is realised to reduce overall power losses and increase power conversion efficiency over a broad range. Furthermore, the leakage inductance energy of transformer is recycled to output with an active clamp circuit. Thus, the voltage stress on main switch is reduced and a low-voltage-rated metal-oxide-semiconductor fieldeffect transistors (with low R DS on) can be used. Moreover, low input current ripple feature is helpful to lengthen life time of renewable energy power sources. Finally, the analysis is described in detail and performance of the proposed converter has been verified through experimental results.