Patent ID: 7560872

Claim:
An apparatus for supplying AC power to a high voltage load comprising first and second half-bridge topology-configured DC-AC converter stages which are operative to drive opposite ends of said load with first and second sinusoidal voltages having the same frequency and amplitude, but having a modulated phase difference therebetween, which is effective to vary the amplitude of the composite AC voltage differential produced across the opposite ends of said load, wherein a respective converter stage contains a pair of pulse generators which generate substantially phase-complementary pulse signals of the same amplitude and frequency, but opposite phase, and having an approximately 50% duty cycle, said phase-complementary pulse signals being used to control ON/OFF conduction of a pair of controlled switching devices, connected in series between first and second voltage terminals and wherein a common connection of said switching devices is coupled to a first end of a primary coil of a step-up transformer, a second end of said primary coil being coupled to a capacitor that is referenced to a prescribed voltage, said step-up transformer having a secondary coil thereof coupled to a resonant filter circuit that is operative to convert a generally rectangular wave output produced across the secondary winding of the step-up transformer into a generally sinusoidal waveform.