Vehicle Xenon Lamp Electronic Ballasts

The present front illumination lamps for cars are usually halogen lamps. Since the successful use of electronic ballast in fluorescent lamps, people's attention of research has been attracted to the electronic ballast of HID lamps.The xenon lamp is one of high-intensity discharge lamps. It has many advantages such as good color rendering; high luminescent efficiency and diversified color presentations. When they are used front illumination lamps of cars, they are able to display some more advantages such as high-brightness, longevity and low energy-cost, etc. However, the xenon lamps have some problems such as a long stand-by period of cold starting, difficulty in hot restarting and the lamp equivalent resistance changing with different time, which is directly related to the parameter design of electronic ballast.Through discussing the characteristics of xenon lamps, including the working principles of xenon lamps, the common features, the electric features of xenon lamps and the transition process, and based on the lamp characteristics of the stand-by state in cold starting, the high voltage in hot restarting, as well as the variation of the lamps' electric features resulted from different powers, this article has designed half-bridge load resonant converters, two-stage voltage increasing ignition circuit, one-stage high voltage ignition circuit and constant power testing circuit to measure and record all kinds of lamp features, and analyze its tendency of variation. Models of gas-filled lamps are introduced as contrast.According to the above-mentioned experiment, the three kinds of control in the operation of xenon lamps are analyzed to provide digitalized xenon lamp electronic ballast with designing methods, and makes research on the steady control of operating xenon lamp electronic ballast.On the basis of above-mentioned work, this paper focuses on the research of ultrahigh pressure gas discharge lamps used as headlights of automobiles. According to xenon lamps' photoelectric properties, corresponding basic requests of the electronic ballast have been put forward. After analyzing the topology of the electronic ballast DC/DC converters, closed-loop stability, aiming at the features of the digitalized 35W xenon lamps' electronic ballast, the paper offers design idea and design result the design of main circuit as well as high pressure ignition circuit to design H-type full-bridge circuit driven by discrete semiconductor devices. After that, it introduces mixed-signal control chip LPC935, and makes detailed analysis and comparison to its core part A/D, PWM, and offers the key flow chart of the system control. Finally, the design is proved reasonable by means of partial work waves of the sample machine. This article has made a comparatively more detailed experiment and research on some problems such as fundamental properties of gas discharge lamps, their testing procedures, modeling methods, control technology, starting ways, and the matching problems of lamps and electronic ballasts. Through design and practice of automobile digital xenon lamp electronic ballast, big helps have been provided for samples to be industrialized.Based on this subject, constructive attempts have been made to promote the nationwide research and application of efficient automobile xenon lamp electronic ballasts.