Folks,
Have to do a flyback-PFC but this time with a really good efficiency, >90%. The output voltage is high enough that sync rectification isn't needed. AFAICT the only other way to boost efficiency is to not flare off the leakage inductance spike via zener or snubber but to recycle it instead. Unfortunately a recuperating winding only works if the duty cycle stays under 50% at all times. Or if it's a double winding 66%, similar in a tapped design, et cetera. Long story short that doesn't work in a PFC because the duty cycle is much higher around the zero crossings of the AC going into the unit.
A non-dissipative snubber such as in Weinberg converters can be iffy because the results are highly dependent on component tolerances in the FET and in the flyback transformer.
Are there any other tricks to sponge off the leakage spike and dump it back into the pot? Maybe a fast and low capacitance "siphoning buck" that only takes off energy when it sees 2x input voltage or something? Must limit kind of hard though.