Analysis And Design Of The Control Strategy Of Electronic Ballast For High Intensity Discharge Lamp

As a new type lighting source, High Intensity Discharge (HID) lamp has some excellent characteristics with high lighting efficiency, good color rendering and long lifetime. It has been more and more popular in these applications including: gymnasium, exhibition, carnie, street lighting. Therefore the development of the drive circuit of the lamp, namely ballast, has become an important research point. The research of this dissertation focuses on the control strategy of electronic ballast. Some control methods are analyzed and compared in this paper. Based on the analysis, a novel control strategy is proposed.At the beginning of this dissertation, modern lighting source and research status are introduced.In chapter II, the physical and electrical characters of HID lamp are discussed in detail. The key requirements for the design of HID power supply are presented, which are: (1) High voltage ignition. General metal halide lamp usually needs at least 3000 volt ignition voltage; (2) Constant power control in steady state, the lamp could suffer the harm of power dithering and over rated power, hence the HID electronic ballast must guarantee the lamp driven under constant output power. Afterwards, general methods of ignition and constant power control are presented.The flyback converter has three current modes: continuous mode, discontinuous mode, critical continuous mode. Based on the discontinuous current mode, chapter III presents a novel constant power control strategy, and detailed simulation results are presented afterwards.In the end of this paper, detail design process for 70W general metal halide lamp is presented, and experimental results are provided to verify the theoretic analysis.