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 stepdown 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, common ground and simple control strategy. A comprehensive analysis of the steady-state analysis, derivation of voltage gain, voltage stress and ZVS condition is presented in detail. Finally, a 30W, 48-to-IV 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.