Comparative Analysis on Soft-charging Schemes of Switched-Capacitor DC-DC Converters

Traditional Switched-capacitor converters (SCCs) can not improve efficiency due to the charge redistribution loss problem of the capacitors. To address this problem, many derivative architectures and operation methods have been proposed. In this work, the current main SCCs topologies for 48V data center application are classified into resonant-based and hybrid-based topologies. The resonant-based topologies are to use resonant switched-capacitors with soft-switching and hybrid-based topologies are cascaded with second-stage magnetic converters which act as controlled current load to achieve soft-charging. Based on these topologies, an analysis and comparison is conducted. An advanced cascaded resonant converter is proposed. Through the reasonable placement of the inductor position, ZCS and ZVS operation can be realized, increasing the power density and efficiency.