Method of controlling resonant push-pull converter

A method of controlling a resonant push-pull converter, the resonant push-pull converter comprising:

• a transformer, comprising a primary-side winding and a secondary-side winding, wherein the primary-side winding comprises a first center-tapped end, a first end, and a second end, and the first center-tapped end is coupled to a DC input voltage, wherein the secondary-side winding comprises two winding ends and a second center-tapped end;
• a first switch, coupled between the first end and a ground end providing a grounding level of the DC input voltage;
• a second switch, coupled between the second end and the ground end;
• a resonant tank, coupled to the secondary-side winding or the primary-side winding, wherein the resonant tank comprises two series-connected branches, and each series-connected branch comprises a resonant inductor and a resonant capacitor connected in series;
• the two series-connected branches are respectively coupled to the two winding ends, and a common contact of the two series-connected output capacitors is coupled to the second center-tapped end;
• a rectifying circuit, coupled to the secondary-side winding, and configured to convert AC power provided by the secondary-side winding into a DC output voltage;
• and
• two output capacitors, connected in series, and the series-connected output capacitors coupled in parallel to an output side of the rectifying circuit to provide the DC output voltage,
• wherein the method comprises a fixed on-time control of:
• controlling the first switch by a first control signal with fixed on-time, and controlling the second switch by a second control signal with fixed on-time so as to alternately switch the first switch and the second switch.