Research On The Start-up Of Low Wattage Metal Halide Lamps

Along with the rapid development of technology, the proportion of lighting consumption continuously increases and natural resources are gradually absent, which make energy-saving a very important project of the scientific research in the world. As a kind of high efficiency energy-saving light source, High Intensity Discharge (HID) Lamp is extensively applied in the field of illumination. Matched with energy-saving light sources is high frequency electronic ballast which has a compact volume, light weight, high efficiency, and high quality of lighting. They are the key of realizing the green-lighting.In Chapter one of the paper, lightening principal and electrical characteristics of discharge lamps are introduced first. Then according to existing references, three main technique aspects of HID ballasts: Suppression of Acoustic resonance, Dimming and Start-up are summarized respectively.Starting-up characteristics of metal halide lamps are analyzed in Chapter two. Main topologies of the electronic ballasts for metal halide lamps are also discussed. Since conventional three-stage low-frequency square-wave electronic ballasts often have problem in starting up low wattage MH lamps instantly and smoothly, this paper presents some optimized control circuits for DC/DC stage, Inverter, and Igniter respectively. The experiment results of a prototype of 70W electronic ballast with these new control circuits verified the probability for lamps to successfully start up instantly and smoothly could increase. Besides, chapter two introduces the complex starting up process of automotive headlamps and the common topology of electronic ballasts. A simple and low cost control design is also presented.Chapter three gives a detailed analysis on two starting-up modes of MH lamps. Metal Halide lamps have very serious acoustic resonance problem. The most widely used method to achieve acoustic-resonance free is low-frequency square-wave electronic ballast with an additional pulse igniter. Compared with high frequency resonance ignition, it needs more devices, such as sidac, thyristor, diac and so on, which increase the complexity and decrease the reliability of the igniter. This paper proposes a novel low cost and high reliability igniter without any extra switch device and feedback control circuit. Theoretical analysis and experiment results of a prototype for 70W MH lamps both have verified the effectiveness of the igniter.