Adaptive transition time measurement in an asymmetrical half bridge

A adaptive transition controller for a resonant converter system, comprising:

• a subtractor circuit configured to produce a difference signal that is a difference between a first signal indicative of a current through an inductor in the resonant converter system and a second signal indicative of a magnetizing current through a transformer in the resonant converter system;
• a derivative circuit configured to receive the difference signal and produce a derivative signal indicative of a derivative of the difference signal;
• a peak detector circuit configured to produce a peak signal indicative of a peak value of the derivative signal over a time period;
• an integrator circuit configured to integrate the peak signal to produce an extension signal;
• and
• a comparator circuit configured to produce an end transition signal when the extension signal exceeds zero;
• wherein the integration circuit includes a first switch is controlled by a gate high side control signal, wherein a gate high side signal controls a gate of a gate high side transistor in the resonant converter system and the first switch is configured to be closed at a beginning of an operation cycle and to be opened during an operation cycle of the resonant converter system.

A method for controlling an adaptive transition time of a resonant converter system, comprising:

• producing a derivative signal that is a derivative of a received first signal indicative of a resonant current through a inductor in the resonant converter system;
• producing a peak derivative signal indicative of a peak value of the derivative signal over a time period;
• integrating the peak derivative signal to produce an extension signal;
• and
• a comparing the extension signal to a second signal indicative of a magnetizing current through a magnetizing inductance of a transformer in the resonant converter system to produce an end transition signal when the extension signal exceeds the second signal.