Single-stage high-power-factor self-oscillating electronic ballast for fluorescent lamps with rapid start

In this paper a new solution to implement and control a low-cost single-stage electronic ballast based on the integration of a buck-boost power factor correction stage and a half bridge resonant inverter is presented The control signals are obtained using the resonant current by means of a saturable transformer. Core saturation is used to control the required dead time between the control pulses on both switches. The turn-on time of one of the inverter switches is controlled to provide proper cathode preheating during the lamp ignition process. No special integrated circuits are required to control the ballast and the total number of components is minimized Analysis and basic design guidelines are presented in the paper together with experimental results obtained from a laboratory prototype.