大功率LED结温与热阻在线测量研究

发布时间：2018-05-28 08:20

本文选题：LED + 结温　；参考：《深圳大学》2015年硕士论文

【摘要】：大功率LED的实际使用寿命远低于其理论寿命,存在可靠性和耐久性问题,从而制约其在高效节能环保照明领域的广泛应用。针对结温和热阻是影响大功率LED器件可靠性的重要因素,本文以实现LED结温与热阻的在线测量为目标,对结温和热阻在线测量原理进行了分析,设计并研发了多通道LED结温和热阻在线测量系统,并结合LED复合过应力加速老化试验系统,对老化过程中大功率LED芯片的结温和热阻变化规律进行了探索性研究。主要工作及结论如下:(1)通过对大功率LED结温与热阻测量方法的大量调研,对小电流K系数法进行了理论分析和推导,提出了减少测试电流引起LED器件自发热影响的小电流K系数法。(2)提出了基于ARM-Cortex M3内核的八通道大功率LED结温与热阻在线测量系统实现方案,实现了大电流压控恒流源及小电流测试恒流源的精确输出以及LED端电压的准确测量。设计了包括K值标定算法、电流标定算法以及结温和热阻测量算法的嵌入式程序,并开发了相应的上位机软件,实现了多通道LED的切换控制和结温与热阻的测量以及数据存储。最后,通过多组实际测试数据对系统的软硬件电路进行了实验验证。(3)将研发出的大功率LED结温与热阻在线测量系统与温度、湿度、振动三综合可靠性试验系统相结合,实现了大功率LED器件在过应力环境下,光、色、热、电等多参数的实时在线测量。(4)利用具有光、色、热、电参数在线实时测量功能的三综合可靠性测试试验机对LED器件在复合过应力条件下,结温与热阻以及光参数的变化规律进行了探索性研究。初步研究发现,大功率LED器件在过载电流驱动下,结温随着工作时间的增加逐渐增加;大功率LED器件结温和热阻的突变,没有引起光通量、色温和光谱较明显的变化。本文研发的大功率LED结温与热阻测量系统能准确有效地在线获得大LED器件工作时的结温及热阻,为LED产业链中相关工艺的精确控制及LED产品可靠性研究提供了有力的依据。
[Abstract]:The practical service life of high power LED is far lower than its theoretical life, which has the problems of reliability and durability, which restricts its wide application in the field of high efficiency, energy saving and environmental protection lighting. In view of the fact that junction temperature and thermal resistance are important factors affecting the reliability of high power LED devices, the principle of on-line measurement of junction temperature and thermal resistance is analyzed in this paper, aiming at the on-line measurement of LED junction temperature and thermal resistance. An on-line measurement system of multi-channel LED junction and thermal resistance was designed and developed. Combined with LED composite overstress accelerated aging test system, the variation of junction and thermal resistance of high-power LED chip during aging was investigated. The main work and conclusions are as follows: (1) the small current K coefficient method is theoretically analyzed and deduced through a large number of investigations on the measurement methods of junction temperature and thermal resistance of high power LED. A low current K coefficient method for reducing the self-heating effect of LED devices caused by testing current is presented. A scheme of the eight channel high power LED junction temperature and thermal resistance on-line measurement system based on ARM-Cortex M3 core is proposed. The accurate output of high current voltage controlled constant current source and small current measurement constant current source and the accurate measurement of LED terminal voltage are realized. The embedded program including K value calibration algorithm, current calibration algorithm and junction and thermal resistance measurement algorithm is designed, and the corresponding host computer software is developed. The switch control of multi-channel LED, the measurement of junction temperature and thermal resistance and the data storage are realized. Finally, the hardware and software circuits of the system are verified by many real test data. The high power LED junction temperature and thermal resistance on-line measurement system is combined with three integrated reliability test systems, temperature, humidity and vibration. In this paper, we have realized the real time on-line measurement of light, color, heat, electricity and other parameters in high power LED devices under overstress environment, using light, color, heat, etc. An exploratory study on the variation of junction temperature, thermal resistance and optical parameters of LED devices under the condition of composite overstress is carried out by three comprehensive reliability testing machines for on-line real-time measurement of electrical parameters. It is found that the junction temperature of high power LED devices increases gradually with the increase of working time under the driving of overload current, and the sudden change of junction temperature and thermal resistance of high power LED devices does not cause the luminous flux, and the color temperature spectrum changes obviously. The high power LED junction temperature and thermal resistance measurement system developed in this paper can accurately and effectively obtain the junction temperature and thermal resistance of large LED devices online, which provides a powerful basis for the precise control of relevant processes in the LED industrial chain and the study of the reliability of LED products.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8

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