A study on dc-dc resonant switched-capacitor converters for LED driving and one application as a VLC transmitter

Abstract

This work presents a family of Resonant Switched Capacitor (RSC) dc-dc converters operating as both high efficiency power converter and fast-response data transmitter for Visible Light Communications (VLC) applications. By operating under soft-switching, the topologies allow for higher switching frequency and higher slew rate, so that the VLC functionality can be embedded into the power stage without an auxiliary switch, which it is a major efficiency bottleneck for higher transmission rates due to its inherent hardswitching operation. This justify new efforts in enabling Pulse-Based Transmission (PBT) without this additional switch. Seven fast-response resonant converters are presented in this work, implemented with a proposed Switched Capacitor Cell and inspired on classic DC-DC topologies (Buck, Boost, Buck-Boost, Flyback, Cuk, SEPIC and Zeta). A 10 W prototype was built to demonstrate such feasibility, operating at a switching frequency of 500 kHz, resulting in nominal efficiency of 85% during data transmission under VPPM scheme, achieving up to 100 kpbs for various brightness levels, over a distance up to 1 m. Given the switching frequency conditions, this prototype is realized using GaN-FETs and Schottky diodes.