A Fully Soft-Switching Semiinterleaved Ultrahigh Step-Down Converter With Wide Load Range, Self-Driven SR, and Zero-Ripple Output Current

In industrial dc-dc power conversion applications, achieving high efficiency and small size in converters is crucial. To address these issues, this article introduces a novel semiinterleaved non-isolated topology by employing coupled inductors and a valley-fill structure. This method ensures continuous output current with zero-ripple, which reduces the size of the output filter. Additionally, by implementing soft switching techniques, the converter can operate at higher frequencies and accommodate a wide range of load variations. The utilization of a pulse frequency modulation (PFM) controller sustains zero-voltage switching (ZVS) and improves the conversion ratio by changing frequency. Also, self-driven synchronous rectifiers (SRs) turn ON and OFF under ZVS circumstances, and valley-fill diodes turn OFF under zero-current switching (ZCS) conditions, thereby lowering switching, diode, and reverse recovery losses, ultimately enhancing converter efficiency. A 300-V to 24-V/12-A prototype of the proposed converter is implemented to verify the performance and the theoretical analysis which results in efficiency higher than 97% from full load to light load.