A single-stage high-power-factor electronic ballast with duty-ratio-controlled series resonant inverter

A single-stage high-power-factor electronic ballast is developed by making an integration of an active filter and a series resonant inverter. The function of power-factor correction is performed by adjusting the duty ratio of the inverter power switches with a simple control circuit. A prototype unit designed for a 36-W compact fluorescent lamp is built and tested to verify the predicted results.