Multi-Resonant Switched-Capacitor Converter: Achieving High Conversion Ratio With Reduced Component Number

Abstract

This article presents a family of resonant switched-capacitor (SC) converters with multiple operating phases, herein named “Multi-Resonant SC Converter”. These converters can be synthesized from the basic two-phase SC topologies, such as the Doubler and the Series-Parallel, and are capable of achieving the same conversion ratio with fewer capacitors and switches. The augmenting inductor can resonantly charge/discharge all flying capacitors at different resonances, thereby facilitating soft-charging and soft-switching operation. Based upon this concept, an 8-to-1 Multi-Resonant-Doubler (MRD) converter and a 6-to-1 Cascaded Series-Parallel (CaSP) converter are proposed and analyzed. Both theoretical analysis and experimental results from a practical implementation are provided to demonstrate the benefits of the multi-resonant approach. The designed hardware prototype is configurable and can achieve one of the best overall in-class performances for the intermediate bus conversion in data centers. At 48-to-6 V conversion, the prototype achieves 98.6% peak efficiency (98.0% including gate drive loss) and 1675 W/in$^{3}$ power density. At 48-to-8 V conversion, the prototype achieves 99.0% peak efficiency (98.5% including gate drive loss) and 2230 W/in$^{3}$ power density.

Keywords

• Circuit topology
• data center power
• DC–DC converter
• high conversion ratio
• hybrid converter
• intermediate bus