A practical and inexpensive implementation of dimmable electronic ballast for compact fluorescent lamps is presented. Popular triac dimmer is used for dimming control, while phase-control methodology is employed in eliminating extra control wires. Various types of passive power factor correctors are examined in replacing active power factor correctors to reduce cost and complexity of the ballast. Charge pump techniques are being investigated in improving the power factor. To achieve stable control of the lamp, especially when it is dimmed down to 10% of its maximum intensity, a novel application of switching frequency modulation is introduced. To minimize the effect due to fluctuation of the power line, feedforward control is added. The design of EMI (electromagnetic interference) filte...[ Read more ]

A practical and inexpensive implementation of dimmable electronic ballast for compact fluorescent lamps is presented. Popular triac dimmer is used for dimming control, while phase-control methodology is employed in eliminating extra control wires. Various types of passive power factor correctors are examined in replacing active power factor correctors to reduce cost and complexity of the ballast. Charge pump techniques are being investigated in improving the power factor. To achieve stable control of the lamp, especially when it is dimmed down to 10% of its maximum intensity, a novel application of switching frequency modulation is introduced. To minimize the effect due to fluctuation of the power line, feedforward control is added. The design of EMI (electromagnetic interference) filter is discussed, in arriving at a good performance lighting system. The thesis also discusses technical details of peripheral circuits for start up, dc supply, and automatic shutdown at low intensity.