Digital implementation of driving scheme for synchronous rectification in LLC resonant converter

A digital implementation of synchronous rectification (SR) driving scheme for LLC resonant converter is proposed in this paper. Compared with analog ones, digital implementation enables more intelligent and precise SR control, improving converter efficiency. In the proposed SR driving scheme, the drain to source voltage of synchronous rectifier on the secondary side is sensed, so that the paralleled body diode conduction is detected. The SR turn-off time is digitally tuned based on the body diode conduction information. For rapid prototyping purposes, the digital tuning system is realized in Cyclone III FPGA.