Hybrid Resonant Switched Tank Converters for High Step-Down Voltage Conversion

In this paper, we propose a new family of modular hybrid resonant switched tank converters (HRSTC) to perform high fixed-ratio 48 V-to-intermediate bus voltage down-conversion in data center applications. These topologies exploit a modular approach to address the challenge of achieving compact and efficient high voltage conversion ratio in a configurable way. The HRSTC leverages the use of a multi-tapped autotransformer (MTA) to enhance the conversion ratio of the switched-capacitor converter (SCC) structure. Additionally, using the residual energy of the MTA leakage and magnetizing inductances, quasi-zero current switching (Q-ZCS) and zero voltage switching (ZVS) commutation is achieved. After introducing, deriving, and analyzing the HRSTC structures, we present a prototype converter for 48-to-3.4 V nominal voltage conversion at 260 A maximum output current. The developed prototype achieves a peak efficiency of 96.6 % and a power density of 920 W/inch 3 . This prototype validates the expected operation and performance of the HRSTC.