LED照明灯具电—热应力加速寿命测试方法的研究

发布时间：2018-03-29 02:21

本文选题：LED灯具　切入点：加速寿命试验　出处：《中国科学院长春光学精密机械与物理研究所》2017年博士论文

【摘要】：发光二极管(LED)是新一代照明光源,已被广泛应用于各照明领域。目前的LED寿命测试主要基于IES推荐标准进行,LED照明产品的测试时间不少于6000小时,这样的测试时长无法适应市场需求。对LED产品加载高于使用条件的环境应力是缩短寿命试验时间的有效手段。LED灯具在不同的应用环境中所受到的环境应力不同,但是温度应力和电应力是始终存在的共性应力,因此研究LED灯具在温度应力和电应力条件下的加速寿命试验方法对实现LED灯具的快速寿命评估和可靠性分析具有重要意义。本文研究了基于Bayes估计的LED灯具电应力加速寿命测试方法。首先搭建电应力加速老化测试系统,分别采用Bayes估计法和中位秩法计算累积失效概率,对比威布尔分布的参数最小二乘估计精度,选用精度更高的Bayes估计法结合逆幂律模型对LED灯具在正常使用条件下的寿命和可靠性进行评估,在失效概率为1%,5%,10%和63.2%时,样品灯具的寿命分别为5677小时,8612小时,10353小时和18407小时。分析了在电应力老化过程中输出电流变化,结果表明输出电流的变化对光通量变化的影响小于0.35%,可以忽略驱动电路老化的因素。研究了LED灯具电-热双应力加速寿命测试方法。首先采用短周期的双应力交叉步进试验确定加速应力极限,并选取合适的应力组合进行老化试验;其次,选用“小电流”正向电压法测试LED样品灯具在各加速应力组合下的结温;再次,采用多元线性回归分析进行艾林模型的参数估计,并根据参数估计结果评估了样品灯具的可靠性。结果表明,在失效概率为1%,5%,10%和63.2%时,寿命值分别为5824小时,8692小时,10375小时和18032小时,与电应力加速试验对比,误差分别为2.59%,0.93%,0.21%和2.04%。最后对样品的颜色退化进行分析表明,荧光粉发光效率的退化是该样品失效的主要因素。根据灯具光通量的e指数衰减,给出了在失效概率50%时,260V电压和300V电压下光衰速率和结温之间的阿伦纽斯方程。研究了加速寿命测试中在线测试和非在线测试的差异。提出一种模拟电应力加速寿命测试中在线测量和非在线测量的方法,采用与积分球内灯具座连接的可调稳压电源实现光色度学参数在线测试和非在线测试的转换,分析两种测试对可靠性预测的影响。结果表明,在大部分情况下,在线测量得到的光通量衰减数据更符合e指数模型,同时,在线测量时的光通量衰减总是略小于非在线测量。失效概率1%,5%,10%,时,预测寿命的相对误差分别为5.8%,4.2%,3.5%。基于t检验的方法,研究了LED灯具样本的相关色温变化和色漂移在两种测试中的差异,在线测试的色温总是大于非在线测试的色温,但是二者的色温变化率和色漂移Du'v'没有显著差异。本文对LED灯具进行了电应力和电-热双应力加速寿命测试,取得了一定的进展,对以后其他种类LED灯具的快速寿命评估和可靠性分析具有一定的指导作用。
[Abstract]:Light-emitting diode (LED) is a new generation of lighting source, which has been widely used in various lighting fields. At present, the life test of LED is mainly based on the recommended standard of IES, and the testing time of LED lighting products is not less than 6000 hours. The length of the test is not suitable for the market. Loading environmental stress above the operating conditions on LED products is an effective means of shortening life test time. Led lamps are subjected to different environmental stresses in different application environments. But the thermal stress and the electric stress are the common stresses that always exist. Therefore, it is very important to study the accelerated life test method of LED lamps under the condition of temperature stress and electric stress to realize the rapid life evaluation and reliability analysis of LED lamps. This paper studies the LED lamps' electrical response based on Bayes estimation. Force accelerated life test method. Firstly, an electric stress accelerated aging test system is built. The cumulative failure probability is calculated by Bayes estimation method and median rank method, and the accuracy of parameter least square estimation of Weibull distribution is compared. The higher precision Bayes estimation method combined with the inverse power law model is used to evaluate the life and reliability of LED lamps under normal service conditions. When the failure probability is 10% and 63.2% respectively, The lifetime of the sample lamps is 5677 hours, 8612 hours, 10353 hours and 18407 hours, respectively. The output current changes during electric stress aging are analyzed. The results show that the effect of the output current on the flux change is less than 0.35, and the aging factor of the driving circuit can be ignored. The accelerated life test method of electric-thermal double stress for LED lamps is studied. First, the short period double stress intersection is adopted. The accelerated stress limit is determined by the fork step test. The appropriate stress combination is selected for aging test. Secondly, the "small current" forward voltage method is used to test the junction temperature of LED sample lamps under each accelerated stress combination. Thirdly, the parameter estimation of Arryn model is carried out by multivariate linear regression analysis. The reliability of the sample lamps is evaluated according to the results of parameter estimation. The results show that when the failure probability is 10% and 63.2%, the life expectancy is 5824 hours / 8692 hours / 10375h and 18032 hours respectively, which is compared with the electric stress accelerated test. The error is 2.590.93% and 2.044.At last, the analysis of the color degradation of the sample shows that the degradation of luminous efficiency of phosphor is the main factor of the failure of the sample. According to the e exponent attenuation of luminous flux of luminaire, The Arrhenius equation between light decay rate and junction temperature at 260V voltage and 300V voltage at 50 failure probability is given. The difference between on-line and off-line measurement in accelerated life testing is studied. A simulated electric stress acceleration is proposed. Methods of online and off-line measurement in life testing, An adjustable power supply connected with the lamp seat in the integral sphere is used to realize the conversion between on-line and off-line testing of optical chromaticity parameters, and the influence of the two tests on reliability prediction is analyzed. The results show that, in most cases, The luminous flux attenuation data obtained by on-line measurement are more in line with the e exponent model, and the flux attenuation in on-line measurement is always slightly smaller than that in the off-line measurement. The failure probability is 1 / 5 / 10, and the relative error of predicting lifetime is 5.842 / 3.5. based on the method of t test, In this paper, the difference of the color temperature variation and the color drift between the samples of LED lamps and lanterns is studied. The color temperature of on-line testing is always larger than that of off-line testing. However, there is no significant difference between the color temperature change rate and color drift Duv'. In this paper, electric stress and electric-thermal double stress accelerated life test of LED lamps have been carried out, and some progress has been made. It can be used to evaluate and analyze the reliability of other kinds of LED lamps.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM923.34

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