New Control Concept for Soft-Switching Flyback Converters with Very High Switching Frequency

A conventional Flyback converter's synchronous rectification switch is controlled from the primary side via opto-isolators; introducing propagation delay. A new control concept is presented here that eliminates the need for opto-isolators, communicating instead through the coupled inductor to assist more precise soft-switching control at much higher frequencies. As a precursor to a 1-MHz GaN demonstrator, an initial 100-kHz prototype has been built to prove the feasibility of the concept.