A Bi-Lateral Energy Resonant Conversion (BERC) Technique for Improved Passive Utilization in Hybrid Switched-Capacitor Converters

Abstract

Hybrid or resonant switched-capacitor (ReSC) based converters are enticing with their high performance in high- and fixed-ratio applications, due to their efficient utilization of both active semiconductors and passive components. In particular, the cascaded or two-stage topologies have shown promising device utilization with least components required for high conversion ratios. This paper presents a novel bi-lateral energy resonant conversion (BERC) technique, that further improves the passive utilization in two-stage topologies by merging voltage- and current-type hybrid SC converters, beneficial in achieving smaller form factor while maintaining high efficiency. The current-type hybrid SC topology, which relocates the output inductor to its input and enables energy process simplification between adjacent cascaded stages, is first introduced in this paper. A 48-to-12 V converter prototype employing the BERC technique is implemented, validated and demonstrated with a very compact size of 0.18 in$^{3}$, along with an excellent overall peak efficiency of 98.8% (including all gate driver losses) using a zero voltage switching scheme designed for BERC. The prototype is tested up to 60 A, thus achieving a power density of 3900 W/in$^{3}$ with a full-load efficiency more than 98%.

Keywords

• Switched-capacitor (SC)
• hybrid
• resonant
• interleaving
• merged inductor
• cascaded