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提出了一种利用质心波长联合半高全宽表征白色LED结温的新方法。首先搭建LED光谱分布测试平台,在忽略脉冲电流热效应的前提下测量在不同环境温度、不同窄脉冲电流下LED的光谱分布。再根据光谱分布计算出质心波长和半高全宽。接着获得双光谱参数与温度和驱动电流的关系曲线图,然后利用实际点灯时的光谱数据,结合关系曲线图,估算出对应的结温。最后考虑脉冲电流的热效应,利用电流-结温修正系数,对先前估算的结温进行修正,得到更加精确的LED结温。研究表明,一般地,LED电流-结温修正系数为-4~-6℃/A,平均为-5℃/A。与正向电压法相比,本设计采用的方法测得的结温最大误差为2.3℃,最小误差为0.8℃,平均误差为1.6℃。因此,采用质心波长联合半高全宽这种非接触型测量方法表征白色LED结温准确可靠。
A new method for characterizing the junction temperature of white LED using centroid wavelength combined with full width at half maximum is proposed. Firstly, the LED spectrum distribution test platform is set up to measure the spectral distribution of LED under different ambient temperature and different narrow pulse current while ignoring the pulse current thermal effect. Calculate the centroid wavelength and FWHM based on the spectral distribution. Then, the relationship between the dual spectral parameters and the temperature and the driving current is obtained, and then the corresponding junction temperature is estimated according to the spectral data of the actual lighting and the relation curve. Finally, considering the thermal effect of the pulse current, the current-junction temperature correction coefficient is used to correct the previously estimated junction temperature to obtain a more accurate LED junction temperature. Studies have shown that, in general, LED current - junction temperature correction coefficient of -4 ~ -6 ℃ / A, with an average of -5 ℃ / A. Compared with the forward voltage method, the maximum error of the junction temperature measured by this design method is 2.3 ° C, the minimum error is 0.8 ° C, and the average error is 1.6 ° C. Therefore, using the non-contact measurement method of centroid wavelength combined with full width at half maximum to characterize the white LED junction temperature is accurate and reliable.