Thermal Analysis of LED Arrays for Automotive Headlamp with a Novel Cooling System

Jang, Sun Ho; Shin, Moo Whan

doi:10.1109/tdmr.2008.923455

Cited by 7 publications

(9 citation statements)

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“…A common system error is LED source variability. The optical properties of different LEDs such as color, radiation pattern, and radiant (or luminous) flux may vary due to thermal variations and errors in the manufacturing process [12][13][14]. The change of performance is around the average values given in the technical data sheets.…”

Section: Random Variations Of Light Flux Among Leds Of the Same Arraymentioning

confidence: 99%

Far-field condition for light-emitting diode arrays

2009

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In practice, any cluster of light-emitting diodes (LEDs) can be modeled or measured as a directional point source if the detector is far enough away from the cluster. We propose a far-zone condition for measuring or modeling propagation of light from an LED array. An equation gives the far-field distance as a function of the LED radiation pattern, array geometry, and number of LEDs. The far field is shorter for high packaging density clusters, and the far field considerably increases with increasing beam directionality of LEDs. In contrast with the classical rule of thumb (5 times the source size), the near zone of an array with highly directional LEDs can extend to more than 60 times the array size. We also analyze the effect of introducing random variations of light flux among LEDs of the array, which shows that far-field variability is low in high packaging density arrays.

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Section: Random Variations Of Light Flux Among Leds Of the Same Arraymentioning

confidence: 99%

Far-field condition for light-emitting diode arrays

2009

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“…Previous researches most often focused on the optimization of packaging materials, geometry configuration, and cooling mechanism of high-power LEDs [8]- [10]. Relatively few studies have been done on transient thermal response.…”

Section: Numerical Model and Transient Thermal Analysismentioning

confidence: 99%

Thermal Stability of High-Power LEDs Analyzed With Efficient Nondestructive Methodology

Lee

Chou

Tseng

2013

IEEE Trans. Device Mater. Relib.

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With the continuing advancement in light-emitting efficiency of high-power light-emitting diodes (LEDs), a nondestructive evaluation on thermal reliability, especially regarding the operating temperature and thermal resistance, which directly affect their lifetime and luminous characteristics, is needed. In this paper, we develop a methodology of using a 3-D numerical simulation for transient thermal-conduction analysis, which is combined with the electrical test method to evaluate the junction temperature of a variety of LEDs. As a result, the simulated temperature for LEDs was found to increase with time, whereas the slug temperature showed the same trend for the simulation and the experiment. The measured results indicate that the thermal resistance of AlGaInP-material-based red and amber LEDs reveals higher variability than that of InGaN-material-based white and green LEDs. Via the luminous flux experiment, we have found that the thermal resistance of the LEDs is not the major determination factor of their luminous flux decay. In contrast, the luminous flux decay of the LED is dependent on the chip material being used. Notably, the slug temperature, observed from the pulsed-driven experiment, of the LED appeared to be lower than that observed in the normal steady operation. It is demonstrated that the lifetime and reliability of high-power LEDs can be improved by decreasing the junction and slug temperatures of the devices. This is important as the slug temperature can be controlled by external cooling techniques. In practice, the developed methodology is not restricted to analyze particular LED packaging forms and can be used to investigate various kinds of multichip LED modules as well.

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“…Furthermore, it possesses longer life cycle, faster dynamic response, smaller device volume and higher color rendering index. LED lighting equipments are widely used for automobiles [1][2][3][4], indoor lightings [5], outdoor lights [6,7], and street lamps recently. LED lighting equipments are look upon as the main lighting equipment in the future.…”

Section: Introductionmentioning

confidence: 99%

Design of High Efficiency Illumination for LED Lighting

Chang

Cheng

Kuo

2013

International Journal of Photoenergy

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A high efficiency illumination for LED street lighting is proposed. For energy saving, this paper uses Class-E resonant inverter as main electric circuit to improve efficiency. In addition, single dimming control has the best efficiency, simplest control scheme and lowest circuit cost among other types of dimming techniques. Multiple serial-connected transformers used to drive the LED strings as they can provide galvanic isolation and have the advantage of good current distribution against device difference. Finally, a prototype circuit for driving 112 W LEDs in total was built and tested to verify the theoretical analysis.

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Thermal Analysis of LED Arrays for Automotive Headlamp with a Novel Cooling System

Cited by 7 publications

References 0 publications

Far-field condition for light-emitting diode arrays

Far-field condition for light-emitting diode arrays

Thermal Stability of High-Power LEDs Analyzed With Efficient Nondestructive Methodology

Design of High Efficiency Illumination for LED Lighting

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