US 7,560,872 B2
DC-AC converter having phase-modulated, double-ended, half-bridge topology for powering high voltage load such as cold cathode fluorescent lamp
Robert L. Lyle, Jr., Raleigh, N.C. (US); Steven P. Laur, Raleigh, N.C. (US); and Zaki Moussaoui, Palm Bay, Fla. (US)
Assigned to Intersil Americas Inc., Milpitas, Calif. (US)
Filed on Jul. 06, 2005, as Appl. No. 11/175,486.
Application 11/175486 is a continuation in part of application No. 11/046976, filed on Jan. 31, 2005, granted, now 7,368,880.
Claims priority of provisional application 60/673123, filed on Apr. 20, 2005.
Prior Publication US 2006/0170371 A1, Aug. 03, 2006
This patent is subject to a terminal disclaimer.
Int. Cl. H05B 37/02 (2006.01); H05B 37/00 (2006.01); H05B 41/16 (2006.01)
U.S. Cl. 315—220  [315/224; 315/226; 315/244; 315/277; 315/291] 21 Claims
OG exemplary drawing
 
1. 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.