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This dissertation, Ultra-low-loss Magnetic Ballast Technology for Modern Lighting Devices by Wai-man, Ng, 吳偉民, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: This thesis presents a research study on the Ultra-low-loss (ULL) magnetic ballast technology for modern lighting devices. The work reported in this thesis in intended to study the high-voltage and low-current features of the T5 high-efficient (T5-HE) fluorescent lamp with ULL magnetic ballast. Also this ULL ballast has been incorporated with the outdoor Light Emitting Diode (LED) street lamp. This thesis contains seven chapters. Chapter 1 introduces a sustainable lighting technology at our society. It should satisfy the criteria of 1) energy saving; 2) long lifetime; and 3) recyclability. According to the CELMA guide [54], electronic ballasts for T5 28W lamps with total power consumption not exceeding 32W (i.e., ballast loss Chapter 2 presents a Class-A2 Ultra-low-loss magnetic ballast for T5 fluorescent lamps. With a better luminous efficacy, lower product and maintenance costs, much longer lifetime, and the use of recyclable metallic materials over its electronic counterparts, this patent proposal provides a truly sustainable lighting solution to the lighting technology. Chapter 3 presents a patent of single design of an ultra-low-loss magnetic ballast for T5 high-efficient (T5-HE) fluorescent lamps rated from 14 to 35W. It is discovered that the same set of ballast parameters can be chosen for operating T5-HE 14-, 21-, 28-, and 35-W lamps at their respective rated power at a mains voltage in the range of 220-240V. This single-ballast design offers great convenience to both ballast manufacturers and users, because only one product design can cover a range of the most popular T5-HE lamps. Chapter 4 presents the analysis of the low-temperature operation at -15℃ and frequent ignition of T5 high-efficient (T5-HE) lamps. Also a bypass resistor is incorporated to each filament to avoid local hot spot and therefore protect the filament. So this patent design can provide a robust, wide temperature range operation, high efficiency and environmental friendly lighting solution to our society. Chapter 5 presents a patent passive offline light-emitting diode (LED) driver which has no controlled semiconductor switches, electrolytic capacitors, auxiliary power supply and control board. This new circuit has the advantageous of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output, and high robustness against extreme weather conditions. Chapter 6 presents an investigation into the effects of the physical and current arrangements of high power LED array systems. Experimental and theoretical results have been proved that, for the same rated power and using the same heatsink, double-string LED structure offers a higher efficacy and total luminous flux than single-string due to the lower devices' junction temperature Chapter 7 concludes the thesis. Subjects: Fluorescent lampsBallasts (Electrici

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