An Ultrahigh Step-Down DC-DC Converter Based on Switched-Capacitor and Coupled Inductor Techniques

High step-down dc-dc converters are widely employed in data center applications. Due to the higher step-down conversion ratio in the new generation 48V voltage regulator module (VRM), a conventional buck converter is not suitable for such applications. To conquer this problem, a novel DC-DC converter is proposed in this paper to achieve an ultrahigh step-down voltage conversion ratio for data centers. The non-isolated topology can be optimally designed to integrate both the switched-capacitor and coupled inductor techniques, which allows Zero-Voltage-Switching (ZVS) of all active switches to be achieved and improves high efficiency. In addition, the converter presents the advantages of lower voltage stress, ultrahigh voltage gain and common ground. A comprehensive analysis of the steady-state analysis, derivation of voltage gain, voltage stress and ZVS condition is presented in detail. Finally, a 30 W, 48-to-1V experimental prototype is built and tested, which validates the ultrahigh step-down voltage gain and soft-switching characteristic of the proposed converter. The maximum efficiency of the prototype is 89.1% and the efficiency is 81.4% in full-load condition.