High-power-factor electronic ballast based on a single power processing stage

A new high-power-factor (HPF) electronic ballast is introduced in this paper. The proposed topology is based on a single power processing stage, and provides a high-frequency voltage to the fluorescent lamps in addition to presenting an HPF to the utility line. The power processing stage is formed by a half-bridge circuit operating above the resonant frequency, thus providing zero-voltage switching. The self-oscillating technique is employed, which increases the converter reliability with great simplicity. HPF is achieved by using a nonconventional boost stage operating in discontinuous conduction mode, which results in a lower DC-bus voltage than that produced by the conventional boost. Theoretical analysis and experimental results have been obtained for two 40-W fluorescent lamps operating at 40-kHz switching frequency and 220-V line voltage.