Ultra-low-loss magnetic ballast technology for modern lighting devices

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 < 4W) can be classified as Class A2, which is the highest class for nondimmable electronic ballast. Apart from the energy saving issue, the environmental issue is another important factor for consideration. The lifetime of electronic ballasts is relatively short (typically 1 to 5 years depending on quality and price), when compared with that of electromagnetic ballasts (typically 10-15 years). Even at the end of the service, the magnetic chokes of electromagnetic ballasts are still recyclable. 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.published_or_final_versionElectrical and Electronic EngineeringDoctoralDoctor of Philosoph