Research On Digital Electronic Ballast For Low Power Metal Halide Lamp At Low Input Voltage

Nowadays, people pay more attention to save and use energy. Green lighting has become the focus of research and development. As a new generation of lighting source, the metal halide lamp has good luminous efficiency and long lifetime, meanwhile the corresponding research and development of electronic ballast has become important than ever before. The electronic ballast is convenient, economical and intelligent, and it replaces the ballast which is widely used.The paper mainly introduces the basic characteristics and principles of metal halide lamp, analyzes its advantages and developing directions in the future. How to restrain the acoustic resonance is always the key to the research of electronic ballast, some characteristics about the acoustic resonance, such as appearance, drawbacks, principles and how to resolve the problem are expounded in detail.Active power factor correction can greatly elevate the power factor of the ballast effectively. The paper offers the circuit of basic boost active power factor corrector, introduces its working principles and how to design the parameters.It also provides the topologies, such as parallel load resonant inverter and half-bridge dual BUCK inverter due to various characteristics of the metal halide lamp at different periods. Particularly, by doing experiments with 120V/100W metal halide electronic ballast is taken into practice and the functions and the characteristics are verified.In order to enhance reliability and complicate control, the paper introduces the digital control strategies with the 8 bits micro-controller, which realizes starting, closed loop, self-protection and so on.