Development Of Deuterium Lamp Power Supply In Visible Spectrophotometer

Spectrophotometry is an effective means of Analytical Chemistry, and such methods are used to determine molecular structure, to do the analysis of materials structure and the determination of the material, according to the absorption of radiation of material-specific wavelength. Because of the advantages of high sensitivity ,reliability, and high speed analysis, it have very wide application ranges in the metallurgical, geological, biological, medical, pharmaceutical, agriculture, semiconductor manufacturing, environmental monitoring, food and health departments.Visible spectrophotometer is analytical instruments developed from the base of the principle of spectrophotometry, and it is photoelectric analytical instruments to do qualitative and quantitative analysis of material using the phenomenon of choosing absorbing light of the material, also, it is a spectrum instrument. In recent years, with the development of optical technology, microelectronics and computer technology, spectrophotometer has been rapid developed and improved, and the sensitivity and selectivity has been greatly improved and will develop toward the trend of automation, intelligent, high-speed and miniaturization, its scope of application has been expanded.A complete visible spectrophotometer include six components: light source, monochromator, the sample pool, detectors, amplification circuits and show results, and deuterium lamp as light source of visible spectrophotometer, has an important role in the entire system. The requirements of spectrophotometer on the light source are that it could provide continuous spectrum in the range of used wavelength, and light intensity is large enough, with good stability. Only sufficient light intensity and good stability can obtain accurate analytical data. Whether deuterium lamps work stably, or affect the stability and performance of the overall system. So as deuterium lamp power supply, it should make deuterium lamps work stably and continuously, and meet the requirements the entire apparatus of miniaturization. From the comparison with the linear power supply and switching power supply, the switching power supply has a small size, light weight and high efficiency, good stability and so on ,which meet the needs of the design.The thesis concisely introduces the development background, present status, trend of development of visible spectrophotometer. Through researching the system of the visible spectrophotometer, we can get the importance of the power supply of the light source. By comparing of linear power and switching power supply, choosing the switching power supply to design the power supply.This thesis can be divided into six chapters. Contents are as follows:Chapter 1 is the introduction, it concisely introduces the visible spectrophotometry and then analyzes present status and trend of development of visible spectrophotometer, finally introduces the research target, meaning and primary coverage.Chapter 2 is the design program of the power supply of the deuterium lamp. Firstly, by analyzing the function of each part of the visible spectrophotometer, we can find the importance of the power supply. By analyze the process of deuterium lamp starter, we can find the power supply modules that the lamp starts and works. By comparing of linear power and switching power supply, the switching power supply is selected.Chapter 3 is the design of the power supply module of preheating. It is designed to constant current circuit according to the preheating conditions. The buck converter is selected as this power supply topology. It analysis the working principle of the buck converter, gives the design parameters, designs the constant current circuit at the sub-loop.Chapter 4 is the design of the power supply module of high-voltage excitation. It is designed to constant voltage circuit according to the exciting conditions. The flyback converter is selected as this power supply topology. It analysis the working principle of the flyback converter, designs the key element-power transformer, gives the design parameters and designs the constant voltage at the sub-loop. Chapter 5 is the design of the power supply module of working. It is designed to constant current circuit according to the working conditions. The boost converter is selected as this power supply topology. It analyses the working principle of the boost converter, gives the design parameters, and designs the constant current circuit at the sub-loop.Chapter 6 is the test results and the error analysis. The design is proved to be satisfied the conditions that the deuterium lamp gets start and work by testing each circuit.Chapter 7 is the summary for this thesis.