High power factor dimmable self-oscillating electronic ballast with variable inductor control

This paper presents a new high power factor dimmable self-oscillating electronic ballast (DSOEB), in which a variable inductor (VI) is used to control the fluorescent lamp (FL) power. Two different approaches are proposed to provide a wide dimming range using a self-oscillating electronic ballast, and a power factor correction (PFC) stage. In the first one, the VI is placed in the series resonant parallel-loaded filter (SRPLI), controlling the rms value of the lamp current with the dc bus voltage supplied by the PFC stage in a closed loop, and in the second one, the VI is placed in the PFC stage, controlling directly the power feeding the inverter. Experimental results for both topologies are presented to evaluate the preliminary performance of the circuit for a 32 W FL.