A Hybird Synchronous Rectification Scheme with Independent Turn-on and Turn-off Timing Control for SiC-Based CLLC Converters

This paper proposes a hybrid synchronous rectification (SR) scheme for CLLC resonant converters. By combining phase tracking and current-based SR advantages, the scheme achieves separate control of turn-on and turn-off timings. The turn-on timing is determined by analyzing the maximum phase shift between primary-side voltage and secondary-side resonant current across the converter’s operating range using a fundamental approximation model (FHA) and simulations. Turn-off timing relies on comparing the SR current with a predefined threshold. Experimental results from a 6.6 kW prototype validate its reliability and stability. With the adoption of this scheme, CLLC converter efficiency is improved, and a higher SR MOSFET conduction ratio is achieved, ensuring reliable and stable SR control in various modes.