A 48-to-12 V Cascaded Resonant Switched-Capacitor Converter for Data Centers with 99% Peak Efficiency and 2500 W/in3 Power Density

Abstract

Resonant switched-capacitor (ReSC) converters are promising alternatives for conventional SC and magnetic-based converters, with the potential to achieve simultaneously higher efficiency and higher power density. Since ReSC converters operate in resonant mode, zero current switching (ZCS) occurs naturally and the V-I overlap switching loss is eliminated. To further reduce the switching loss (transistor Coss loss) and improve the light-load efficiency, zero voltage switching (ZVS) is desired. In this work, a ZVS control technique is implemented on a cascaded resonant based intermediate bus converter for 48-to-12 V data center power delivery, on a 720 W hardware prototype. The efficiency is maintained above 97% starting from 3% of the rated load, and has a peak of 99% (including gate drive loss). In addition, the prototype has a very high power density of 2500 W/in3.