Improved Sensorless Synchronous Rectification for CLCResonant Based Converter

Abstract:
This paper presents a detailed analysis of synchronous rectification (SR) in CLLC resonant converters, introducing a sensorless methodology for characterizing turn-on and turn-off delays. The study employs transient electrical simulations to accurately capture the switching behavior and delay characteristics of the CLLC converter. Through a combination of simulation and experimental validation, the research identifies the sources of these delays, evaluates worst-case scenarios, and proposes a novel two-variable control strategy based on switching frequency and output voltage. The findings suggest that the sensorless approach could achieve accuracy comparable to sensor-based techniques while improving overall efficiency and reliability. Moreover, the proposed method simplifies implementation and enhances converter performance, making it a compelling alternative for advanced power electronics applications. The results of this study can be extended to LLC-based converters operating in both forward and reverse modes.