A Soft-Switching High-Gain DC–DC Converter Employing an Active-Clamp Circuit

Abstract

A soft-switching high step-up DC–DC converter based on the coordinated integration of an input inductor, a three-winding coupled inductor, a switched-capacitor voltage multiplier, and an active-clamp circuit is developed in this work. High voltage gain is achieved using the input inductor, switched capacitor voltage stacking, and the coupled inductor. The input inductor smooths the input current while participating in energy transfer and capacitor charging, thereby enhancing the boosting capability. The transferred energy is further amplified by multiple secondary windings. The reflected secondary voltage reduces the effective voltage across the magnetizing inductance, which suppresses energy storage and promotes energy transfer to the output, resulting in enhanced voltage gain. Meanwhile, intermediate capacitors are charged and connected in series with the input and induced voltages, enabling a high conversion ratio without requiring excessively high duty cycles or bulky turns ratios. The active-clamp circuit reutilizes leakage energy and suppresses voltage stress, while the recycled leakage energy further participates in the voltage-boosting process. It also facilitates zero voltage switching through a resonant transition, thereby reducing switching losses and high-frequency switching transients. Small-signal analysis, dynamic response evaluation, and thermal verification are also presented to validate the stability and practical feasibility of the proposed converter. Experimental results demonstrate 97.88% and 96.9% efficiency at 80 W and 200 W, respectively, under 36 V/400 V operating conditions, making it a promising candidate for renewable energy systems.