Research On Electronic Ballast Of Metal Halide For Automotive Headlights Based On Digital Control

Metal halide lamp as a high intensity gas discharge lamps, with good color,condenser capacity, long life, etc., are suitable for using as vehicle headlamps. Butthis particular gas discharge lamp is so hard to be started and the starting process iscomplex. Converter designing and controlling problems are faced in the practicalapplication of electronic ballast.So a sophisticated and reliable electronic ballastwhich can achieve its requerment of starting is needed.The start-up characteristics of vehicle metal halide lamp are analyzed in this article,and then the feasible plan of electronic ballast for it is proposed by studying theacoustic resonance problem, basic topology, ignition circuit and some otheraspects.Vehicle metal halide lamp as the researched object is studyed in this paper. DC/DC converter as key components of metal halide lamp electronic ballast is in-depthanalysised. A high efficiency coupled inductor DC/DC converter which can be usedas vehicle electronics ballast is studied. The circuit efficiency is improved by passiveclamp circuit. The PSPICE software is used for simulation analysis. According to aspecial lamp starting characteristics,a suitable digital controlling method isapplied.Every starting stage of the lamp is controlled by the digital chip to achievemetal halide ballast and load characteristics having a good match.Finally, the prototype test is conducted, the experimental results are given to verifyits validity.