The Research Of Some Critical Issues In The Application Of The Non-Resonant High Frequency Dimmable Electronic Ballast For The Metal-Halide Lamps

As a high efficiency, long life, and high color rending lighting source, Metal Halide (MH) Lamps play an important role in the Green Lighting Projects. Therefore, development of the driving circuit of the lamp, namely the electronic ballast has become an important research object. Because of the light weight, high efficiency, easy intelligent control, the electronic ballast will gradually take the place of the traditional electromagnetic (EM) ballast whose characteristics are heavy in weigh, low in efficiency, unable for intelligent control.At the beginning of the thesis, the background of the project, the fundamental knowledge of the modern lighting source and some characteristics of the High Intensity Discharge (HID) lamps are introduced. Then the purpose of the research is given. As the MH lamps have the acoustic resonance problem, the application of the ultra-high frequency mode could efficiently solve the problem. However, at the same time, it takes some difficulties to the design of the electronic ballast. The difficulties we face include that high and wide enough ignition pulse are necessary when the MH lamps start up, but the common used igniter circuits could not provide the required pulse. Besides, as the frequency increases, the higher request would be needed for the reliability of the ballast. At last, the ballast should have the ability to implement the intelligent control, for example, the dimming control and so on.The accessory igniter circuit has been widely used for its high reliability and low current stress. On the basis of the research of the two work mode of the common used series accessory igniter circuit, a new parallel accessory igniter is demonstrated in chapter two. The basic principle of the introduced igniter is to split the functions of the transformer in the series accessory igniter. With the help of the simulation and experiment results, it is proved that this practical and reliable igniter could satisfy the demand of the MH lamps when they start up at a high frequency.The implementation of the ZVS in the bridge arm of the inverter is necessary for the ballast to be efficient and reliable. The switch environment of the MOSFET in the inverter in different load condition is analyzed in chapter three. On the basis of that, a solution is provided for the open-circuit condition when the MH lamps are not breakdown. The experiment results have proved the effect of the solution.DALI, which is a universal intelligent dimming protocol, is introduced in chapter four. The design process of the DALI dimming module for the 150W MH lamps is also given. The experimental dimming could range from 100% to 38%, and the acoustic resonance does not appear during the dimming process.