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Lamp modeling and design of IC controller for dimmable electronic ballast

Authors Ng, Alex Tsz Kit
Issue Date 1999
Summary Lighting accounts for 25% of the total electric energy produced, and improvement in efficiency of lighting appliances would surely ease energy consumption. The efficacy of fluorescent lamps is 4 times higher than that of traditional light bulbs (80 lm/W vs 20 lm/W), while electronic ballasts excel over magnetic ballasts by 10% to 15% due to switching at high frequency (~ 30kHz) rather than at line frequency. Dimmability is desirable for various applications that would also contribute to the reduction of power dissipation as lighting requirements may not require full intensity all the time. Existing dimming schemes do not cope with well-received electronic dimmers that are popular for dimming light bulbs. This research describes a phase-controlled dimming method for fluorescent lamps that uses a modified triac dimmer. It eliminates an extra control wire that is needed in some existing designs, and the small cut-in angle ensures a high power factor and low total harmonic distortion. In order to predict the performance of the lamp system and to achieve an optimal design of the electronic ballast, a comprehensive mathematical model which incorporates the negative dynamic resistance of fluorescent lamps is derived. A circuit model that is suitable for SPICE simulation is also derived from the mathematical model and simulation results are presented. Lamp characterization confirms the validity of the model. An integrated circuit controller using a 2μm Orbit NWell CMOS process is designed and fabricated, which drives a 23W compact fluorescent lamp successfully.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 1999
Language English
Format Thesis
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