Automotive Headlamp High Power Led Cooling System and Its Effect on Junction Temperature and Light Intensity

Abstract

Halogen bulbs are sources of light of headlamps of most of the vehicles running around the world. To get better night vision, vehicle owners want to replace the conventional halogen bulbs with HPLEDs without replacing the conventional headlamp assembly. Though High Power Light Emitting Diodes (HPLED) are efficient sources of light for replacing halogen bulbs, conventional headlamps are not designed for HPLEDs and so replaced HPLEDs will fail within a short duration due to poor cooling. The aim of this work is to develop a compact cooling system for a conventional headlamp assembly to accommodate HPLEDs. An air cooled system with a compact heat sink is proposed in this work. To decide the dimensions of the compact heat sink various heatsink sizes were modeled and simulated in ANSYS. For this study, a popular SUV's headlamp is chosen and complete tests were carried out in absence of external lights on a flat black surface for about 28 meters. The light intensity is measured in terms of lux for Halogen and HPLED's horizontal passing beam at various test points. For generating the same intensity of light, it was found from the experimental results that the HPLED consumes only one third of the energy supplied to halogen bulbs. With the proposed cooling system the junction temperature was reduced by about 25% when the cooling fan is operated at laminar flow conditions. On the other hand, the luminous intensity of the HPLED improved by about 30.9% due to the decrease in junction temperature. The HPLED headlamp reflector inner wall temperature is found to be 49 % lesser than Halogen bulb headlamp reflector inner wall temperature.

Numerical investigation of the effect of different heat sink fin structures on the thermal performance of automotive LED headlights

“…The average operating life of an LED is around one hundred thousand hours when properly cooled. The LED system's luminous efficiency, measured in lumen output per watt provided, is 160% higher than the Xenon system's [22]. For these and similar reasons, this study focuses on the LED headlight.…”

“…Researchers have also focused on heat problems in-vehicle LED headlights. Recent studies on automotive LED headlights have been focused on new designs [16][17][18][19][20][21][22]. Jang and Shin [16] investigated the thermal performance of a new cooling system for a light-emitting diode headlamp module.…”

“…As a result, the proposed method always suggested feasible fin structures with optimum properties for certain LED designs. Chidambaram and Arunachalam [22] have designed a new high power automotive LED headlight and tested it at 16 W. While the junction temperature was 116 ºC under natural convection, it was reduced to 87 ºC at 1.9 m/s air velocity. Singh et al [23] offered heat pipe-based cooling solutions.…”