Soft-charging operation of switched-capacitor DC-DC converters with an inductive load

Switched-capacitor (SC) converters are becoming a strong candidate for high power density converters. Traditionally, these SC converters have suffered from two main problems: capacitor charge transfer loss and lossy output voltage regulation. This paper proposes a hybrid SC converter topology that addresses both problems simultaneously. The proposed topology adds a single small inductor to the SC converter and compares favorably in terms of efficiency and power density to both SC converters and buck converters. Unlike SC converters, it can maintain its efficiency for output voltages that are lower than the nominal value determined by the topology. A discrete prototype with a large step-down ratio of over 8-to-1 and a power rating of 30 W has been designed and built to demonstrate the potential of the hybrid converter.