Hard- and Soft-Switched
Technical Lecture Session
Hybrid DC-DC Converters
dc-dc, boost, switched capacitor, soft-switching
This paper presents a LEGO-Boost architecture for high-ratio voltage conversion applications. The LEGO-Boost architecture is a merged-two-stage architecture: the resonant voltage doubler stage and the switched-capacitor stage are merged together to create mutual advantages. The operation principles of the LEGO-Boost converter are introduced, together with the switching strategies to achieve soft-charging and soft-switching. The LEGO-Boost architecture offers reduced switch stress, improved efficiency and power density, automatic voltage/current balancing, and very high modularity. We performed detailed loss analysis and two different methods are introduced to improve the efficiency. The effectiveness of the LEGO-Boost architecture is verified by a 20 V-240 V, 535 W prototype with peak efficiency of 94.2% and power density of 216 W/in^3 for photovoltaic and fuel cell applications.