Thesis (Ph. D.)--Drexel University, 2005. / Includes abstract and vita. Includes bibliographical references (leaves 175-186).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 36 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 21).

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This dissertation proposes a new starting profile with some modifications to the definition of American National Standards Institute (ANSI) to interpret the starting process of fluorescent lamps driven by high- frequency electronic ballasts. To identify the times of preheating, ignition, and steady-state, the staring transient waveforms of lamp voltages as well as the lamp currents are scrutinized from the experiments on a diversity of ballasting techniques. A glow-to-arc transition is considered to account for the stage between glow discharging and a stable lamp arc. In addition, the filament preheating is not limited to the constant voltage but can be current preheating which is more commonly used in commercial products. By the new definition, the glow current and the glow-to-arc current can be calculated to evaluate the lamp starting performance. The applicability of the starting profile is confirmed experimentally by the instant-start, preheat-start, rapid-start, modified rapid-start, and programmable rapid-start schemes.

Read before the Royal Photographic Society of Great Britain on December 14th, 1915.

Med ett naturligt fältexperiment studeras betydelsen av social påverkan för individers benägenhet att skänka pengar. Den dominerande teorin inom nationalekonomin som förklaring till välgörenhet är warm glow altruism. Teorin säger att människor skänker pengar på grund av en kombination av altruism och warm glow. Men det finns även teorier som förutsäger att socialt tryck spelar roll. I experimentet ställdes frågor till pantkunder om deras bidrag till välgörenhet. Individerna i behandlingsgruppen blev tillfrågade innan de började panta och kunnat välja om de ska skänka panten. I kontrollgruppen besvarades frågorna efteråt. Resultatet tyder på att social påverkan spelar stor roll för benägenheten att skänka panten.

<p>Med ett naturligt fältexperiment studeras betydelsen av social påverkan för individers benägenhet att skänka pengar. Den dominerande teorin inom nationalekonomin som förklaring till välgörenhet är warm glow altruism. Teorin säger att människor skänker pengar på grund av en kombination av altruism och warm glow. Men det finns även teorier som förutsäger att socialt tryck spelar roll. I experimentet ställdes frågor till pantkunder om deras bidrag till välgörenhet. Individerna i behandlingsgruppen blev tillfrågade innan de började panta och kunnat välja om de ska skänka panten. I kontrollgruppen besvarades frågorna efteråt. Resultatet tyder på att social påverkan spelar stor roll för benägenheten att skänka panten.</p>

Three programmed rapid-start control schemes for the electronic ballasts with a half-bridge series-resonant inverter are proposed to improve the starting performance of the rapid-start fluorescent lamps. Included are: (1) programmed rapid-start control scheme with an ac switch, (2) programmed rapid-start control scheme with inductively coupled filament-heating circuit, and (3) programmed frequency control scheme with a series-resonant energy-tank. The first control scheme is simply to add a solid-state ac switch onto the series-resonant electronic ballast to provide programmed rapid-start for the rapid-start fluorescent lamp. The ac switch is turned on to have a zero voltage across the lamp to eliminate the glow current during the preheating interval. By adjusting the operation frequency and the duty-ratio, the electronic ballast produces first an adequate resonant current for preheating the cathode filaments, then a sufficiently high lamp voltage for ignition, and finally a stable lamp arc of the required lamp power. The second control scheme is accomplished by adding two auxiliary windings on the inductor of the power-factor-correction (PFC) circuit for the filament-heating circuits. During the preheating period, the PFC circuit is activated to provide the filament heating while the inverter remains idle to keep the lamp voltage at zero and hence to eliminate the glow current. After the filaments have been heated to the appropriate temperature, the inverter is initiated to ignite the lamp and then operate it at the required power. The third control scheme is realized by programming the operation frequency of the electronic ballast with an additional series-resonant energy-tank on the load resonant network. During the preheating interval, the electronic ballast is programmed to operate at the resonance frequency of the series-resonant energy-tank to reduce the lamp voltage and hence to eliminate the glow discharge. With carefully designed circuit parameters, the electronic ballast is able to provide an adequate current for preheating. After the emission temperature has been reached, the operation frequency is adjusted to generate a high lamp voltage for ignition, and then is located at the steady-state frequency driving the lamp with the desired power and filament current. In this dissertation, the mode operations of the proposed ballast circuits are analyzed in accordance with the conducting conditions of the power switches. The equivalent resistance model of fluorescent lamp is implemented to calculate the performances of the ballast-lamp circuit at steady-state. The design equations are derived and the computer analyses are performed with the fundamental approximation on the equivalent circuit models of fluorescent lamps. In addition, in order to accurately predict the operating characteristic of the preheating circuit, a mathematical model is developed to interpret the variations of the filament resistance during preheating. Finally, the laboratory electronic ballasts with the proposed control schemes are built and tested. Satisfactory performances are obtained from the experimental results.

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.