Low-cost single-stage electronic ballast based on a self-oscillating resonant inverter integrated with a buck-boost PFC circuit

In this paper, a new solution to implement and control a 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 from the inverter resonant current by means of a saturable transformer. Core saturation is used to control the required dead time between the control pulses of both switches. Since no special integrated circuits are required to control the ballast, the total number of components is minimized and the final cost of the ballast is reduced compared to a typical two-stage configuration. Analysis and basic design guidelines are presented in the paper, together with experimental results obtained from a laboratory prototype.