A Novel Single-Stage High-Power-Factor Electronic Ballast With Symmetrical Half-Bridge Topology

This paper proposes a novel single-stage high-power-factor electronic ballast with symmetrical half-bridge topology for fluorescent lamps. The proposed electronic ballast only uses a symmetrical half-bridge topology to procure the functions of a boost power-factor-correction converter and a half-bridge series parallel-loaded inverter. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in-phase supply current. The conventional electronic ballast circuit has larger conduction losses because its power-factor-correction (PFC) power flow path 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 only two conduction drops in the current flow paths. Therefore, it can provide lower conduction loss compared to the conventional one. A prototype circuit designed for a 40-W fluorescent lamp operating at 50-kHz switching frequency and 110-V line voltage is built and tested to verify the analytical predictions.