Influence of Ambient Temperature on Optical Characteristics and Power Consumption of LED Lamp for Automotive Headlamp

Abstract

In this study, the authors propose a method for evaluating the influence of ambient temperature (Ta) on the optical characteristics and power consumption of a LED lamp used for the automotive headlamp, which helps the designer to figure out the acceptable range of the ambient temperature for the LED lamps to work well in the practical case. The LED lamp was fixed on the test holder and placed in a fixed position in the air circulation temperature control oven to measure the illuminance, spectrum in three different directions, and power consumption under various Ta. The experimental results indicate that Ta has little effect on the correlated color temperature (CCT), chromaticity coordinates, and angular distribution of the emitting light. In contrast, Ta has a significant effect on the lamp’s resistance, thus affecting illuminance and power consumption. When the Ta increased from 30 °C to 60 °C, the illuminance of the low beam and high beam decreased on average by 16.6% and 21.7%, respectively, while the power consumption of the low beam and high beam decreased on average by 21.4% and 22.2%, respectively. The drop in the luminous flux output indicates the probability of originally qualified automotive LED headlamps becoming unqualified in high Ta.

Operation of Electronic Devices for Controlling Led Light Sources When the Environment Temperature Changes

“…The dependence of LEDs relative current change for LED lamp on the relative network voltage change can be written as follows [11,16]…”

“…This was explained by the fact that despite the ability of ВР2863 chip to stabilize the output current also when the environment temperature changes, as it follows from its technical characteristics, the luminous flux of LEDs at current constant value still de- The luminous flux of the lamp decreases by 5% with increasing temperature (Figure 17), but not so significantly as it happens in the lamps with linear driver without current stabilization. This was explained by the fact that despite the ability of BP2863 chip to stabilize the output current also when the environment temperature changes, as it follows from its technical characteristics, the luminous flux of LEDs at current constant value still decreases with increasing temperature [11]. The current through LEDs, as well as the luminous flux of Premier-10 lamp, contains slight high-frequency pulsation (Figure 18).…”

“…To achieve these goals, we will provide a study of the characteristics of LEDs that can be used to assess the effect of temperature environment on the light and electrical parameters of the LED device, namely: the dependence of the forward voltage of the LED Ud on the temperature Tc at a constant (nominal) value of the current and the dependence of the relative value of the luminous flux of the LED F/F0 from the temperature T c [11].…”

Modelling and Thermographic Measurements of LED Optical Power

“…Heat transfer analysis can support the investigations of optical phenomena. In the literature, there are numerous thermal analyses of LED structures based on different modelling approaches, such as 3D-FEM (finite element method), analytical conjugate analyses, and compact simplified models [ 4 , 9 , 10 , 11 , 12 , 13 ]. In this research, a heat transfer analysis using compact 3D-FEM modelling was performed to validate the obtained experimental results.…”