Real-time adaptive timing control of synchronous rectifiers in high frequency GaN LLC converter

This paper presents an adaptive synchronous rectification (SR) control method for high frequency GaN LLC converter. This novel SR control scheme adaptively controls SR on time as well as accurate turn-on and turn-off tuning. Zero crossing detection (ZCD) of the transformer secondary-side current is achieved by Rogowski coil and its auxiliary circuits. ZCD signals are sent to digital signal processor (DSP) for further signal processing and PWM modulation. The SR method is applicable for a wide range of load current and wide range of switching frequency. To verify the proposed SR control method, a 2.1 kW GaN LLC converter prototype is demonstrated with 400V input voltage and 48V output voltage.