Resonant power converters. Example embodiments are methods of operating a rectification controller including sensing a drain-source voltage of a synchronous rectification (SR) field effect transistor (FET); setting an adaptive delay time corresponding to a time interval between a first state transition and a second state transition, with each of the first and second state transitions corresponding to the drain-source voltage transitioning between being greater than the adaptive delay voltage and being less than the adaptive delay voltage; and driving the SR FET to a conductive state after the drain-source voltage having been less than the on-threshold voltage for longer than the adaptive delay time.