Resonant Soft‐Switching Diode‐Clamped Converter With Wide Output Range

ABSTRACT

To meet the requirements of high efficiency and high power density in wide‐voltage‐range lithium‐ion battery charging for small‐scale uninterruptible power supply (UPS) applications, this article proposes a resonant soft‐switching diode‐clamped converter with a wide output range. By integrating a boost leg into a diode‐clamped half‐bridge resonant converter, the proposed topology realizes step‐up regulation through the boost energy‐storage interval of the resonant inductor, while step‐down regulation is achieved by adjusting the duty cycle of the half‐bridge switches. In this way, wide‐output‐voltage operation is obtained at a fixed switching frequency without relying on a reduced switching frequency or a deliberately small magnetizing inductance, which improves the design flexibility of the resonant tank and magnetic components. The diode‐clamping network provides a resonant‐current freewheeling path in buck mode and limits the resonant‐capacitor voltage during hard‐start operation, thereby reducing unnecessary energy circulation and suppressing voltage overshoot. In addition, the proposed modulation and parameter design enable ZVS and ZCS characteristics under the designed operating conditions. A prototype is built to verify the proposed converter over an input‐voltage range of and an output‐voltage range of . Experimental results confirm the expected boost, buck, soft‐switching, transient, and hard‐start characteristics, and a peak efficiency of is achieved.