Single-switch high-power-factor electronic ballast for compact fluorescent lamps

A novel single-switch high-power-factor electronic ballast, which is the integration of a buck-boost AC-to-DC converter and a Class-E load resonant inverter, is designed for compact fluorescent lamps. The electronic ballast can achieve nearly unity power factor by operating the buck-boost converter at discontinuous conduction mode (DCM). With carefully designed circuit parameters, the active power switches can be switched-on at zero current, leading to a high circuit efficiency. Design equations based on fundamental approximation are derived and computer analyses are performed to determine circuit parameters. A prototype. for a 27 W compact fluorescent lamp was built and tested to verify the analytical predictions. Satisfactory performances are obtained from the experimental results.