Исследование изменений характеристик светодиодных матриц бортового светильника при токовых испытаниях.

Abstract

The paper presents the results of studies of changes in the characteristics of LED COB matrices of the GW P9LR31.EM - DURIS S 8 type as part of a LED luminaire when tested under the direct current in a continuous mode and in an electrocycling mode. The arrays consist of eight InGaN/GaN LED dies connected in series, coated with a phosphor. Calculation in the Comsol Multiphtsics environment of the temperature field of the luminaire at the rated operating current and free convection heat transfer showed that the maximum overheating of the matrices does not exceed 46 K, and the difference in their temperatures is 2 K. At the same time, the experimental values of the thermal resistances of the matrices of a real lamp vary from 42 to 58 K/W. Before testing, the I-V characteristics of the matrices differ markedly in the level of leakage current in the voltage range from 14 V to 19 V, and the LEDs in the luminaire matrices have a significant spread in the brightness of emission in the microcurrent mode. The degree of this scatter within each matrix was estimated by measuring the luminescence brightness of each die of the matrix and calculating the coefficient of variation γ. It was found that the coefficient of variation of the emission brightness of the COB matrix dies measured at a current of 100 nA strongly correlates with the leakage current. When testing a luminaire under the direct current, the most significant changes in the electrophysical and optical characteristics of COB matrices are observed in the range of microcurrents: the distribution of the emission brightness of the matrix dies at a current of 100 nA becomes more uniform. The greatest changes in matrix characteristics were observed after the first 700 hours of testing, that is, at the running-in stage. At the same time, no correlation was found between the degree of change in the characteristics of the matrices during tests and their thermal resistances.