Fluorescent lamps are nowadays the most important light sources in industrial, commercial, and domestic applications. To drive fluorescent lamps, electronic ballasts with high-frequency resonant inverter, instead of the electromagnetic ones, are increasingly used due to the benefits of lightweight, small size, high luminous efficiency, and long lamp life. Recently, efforts are concentrated on how to reduce the product cost as well as to improve the circuit performances. To further curtail the product cost, the power-factor-correction circuit is integrated into the ballast circuit as single-stage high-power-factor electronic ballast. On the other hand, the unit cost per lamp can be substantially reduced by developing a ballast circuit which is capable of driving multiple lamps. For convenient use, the user may turn on the desired number of the lamps in accordance with the expected luminosity. A starting-aid circuit is added to eliminate the glow current during preheating. In addition, a protection circuit will be included in the multi-lamp electronic ballast. In case of operating partial lamps, a high power factor at the line input will be always retained. In this thesis, the feasible circuit configuration is developed and design equations are derived. Accordingly, design guidelines for determining circuit parameters are provided. The laboratory circuits are built and tested to verify the computer simulations and analytical predictions.

This thesis investigates the impact of preheating and glow current on the life-time of rapid-start fluorescent lamps during the starting transient period. A set of electronic ballast circuit is designed to adjust the starting transient preheating current, open-circuit voltage, and preheating time, so that the preheating conditions and the intended amount of glow current can be scheduled. In the experiments, the tested lamps are frequently switched on and off for 35 seconds and 25 seconds, respectively, to accelerate the life-cycle test. Experimental results show that the effect of the glow current on the life-cycle is trivial. Insignificant difference is found between the test lamps with different glow currents when the preheating conditions are the same. On the other hand, the preheating degree is found to be the main factor that affects the lamp life-time. The tested lamps which are adequately preheated last for more than 100000 test cycles. On the other hand, the tested lamps with insufficient preheating are premature with black ends or even damaged only after the several thousands cycles.

This thesis proposes a single-stage high-power-factor electronic ballast with series-resonant inverter for rapid-start fluorescent lamps with zero glow current during preheating period. A buck-boost converter is integrated into the ballast as the power-factor-corrector. Two auxiliary windings are wound on the same core of the buck-boost inductor for filament heating. During the preheating period, the buck-boost converter is initiated while the series-resonant inverter is disabled by controlling the corresponding active power switches. Due to zero voltage across the lamp, the glow current can be effectively eliminated. As the filaments reach appropriate emission temperature, the series-resonant inverter is activated. The lamp is then ignited and consequently operated at the rated lamp power. Circuit analyses and experimental tests of the proposed preheating control scheme are carried out on an electronic ballast for a T8-40W rapid-start fluorescent lamp.