Patent ID: 7054176

Claim:
A multistage, push-pull driven, resonant DC-AC converter comprising a plurality of push-pull DC-AC converter stages, each push-pull DC-AC converter stage containing a first controlled switching device having a current flow path therethrough coupled between a prescribed reference voltage and a first end of a first coil portion of a center-tapped primary winding of an output transformer, and a second controlled switching device having a current flow path therethrough coupled between said prescribed reference voltage and a first end of a second coil portion of said center-tapped primary winding of said output transformer, power for said respective DC-AC converter stage being supplied by coupling said center-tap of said primary winding to a current source, and further including a capacitor coupled between said first ends of said first and second coil portions, so as to form therewith a resonant LC tank circuit, and cause the switched output of said respective DC-AC converter stage to have a generally sinusoidal waveform, which is extracted at output terminals of a secondary transformer winding mutually coupled with said first and second lower coil portions of said primary winding, and wherein center-taps of primary windings of said plurality of push-pull DC-AC converter stages are connected in common to said current source, and wherein switching times for control inputs of said first and second switching devices of said respective push-pull DC-AC converter stages are defined in accordance with times at which a resonating voltage at the connected-in-common center-taps of said primary windings crosses zero volts.