Electronic ballast with programmable starting for rapid-start fluorescent lamps

A single-stage high-power-factor electronic ballast is developed to operate rapid-start fluorescent lamps with programmable starting. A buck-boost converter for power factor correction is embedded in the series resonant inverter as the single-stage configuration. Two auxiliary windings are added on the inductor of the buck-boost converter for separately heating the lamp filaments. During the preheating stage, the resonant inverter remains idle to keep the lamp voltage at zero and hence to eliminate the glow current, while the buck-boost converter is initiated to provide the filament heating voltage. After the filaments have been preheated to an appropriate emission temperature, the resonant inverter is activated to ignite the lamp and then operate it at the required power. The starting scenario is simply accomplished by frequency control. To illustrate the operation of the proposed circuit, a prototype for driving the T8-36 W lamp is designed, built and tested.