A Novel Single-Switch Single-Stage Electronic Ballast With High Input Power Factor

This paper proposes high-power-factor electronic ballast for fluorescent lamps. The converter offers a high input power factor and a high-frequency supply to the lamp using a single switch. Besides the simple circuit configuration, the excellent performances of high power factor for ac input side and low lamp crest factor for lamp are included in this paper. The conventional electronic ballast circuit has larger conduction losses because its power flow path of power factor correction (PFC) circuit always includes two diode losses from the front-end bridge rectifier and one power switch loss. The PFC power flow path of the proposed circuit has three semiconductor conduction drops when the active switch is on and two semiconductor conduction drops when the active switch is off. Therefore, it can provide lower conduction loss than the conventional one. The design equations are derived from the analyzed results based on fundamental approximation, and then an easy-to-use design tool is provided accordingly under considerations of filament heating and ignition. A prototype circuit that operates at 40-kHz switching frequency and 110-V line voltage for one 40-W fluorescent lamp is built and tested to verify the analytical predictions