Robust Synchronous Rectification Driving Technique for Bidirectional CLLC Resonant Converters

Abstract:
One of the biggest challenges in high-voltage bidirectional CLLC resonant converters, in achieving high efficiency, is to properly drive the synchronous rectification (SR) stage in all operating conditions. This paper focuses on a simple and robust sensing and driving technique developed for a 7kW bidirectional SiC based power converter for battery charging applications, which operates over a wide output voltage range. This paper demonstrates how the implemented method is suitable even when the CLLC converter operates below the resonant frequency and then, when the devices of the SR stage should be turned-off before the end of the half switching period.