Research Of LED Headlamp Thermal Management Based On EHD

Automotive lighting system, as a significant part of a car, consumes a lot among the total energy cost in daily driving. As a result, an efficient, low-energy-consumption,safe and reliable automotive lighting technology is obvious significant. As the "green light-source" of the 21 th century, LEDs are affirmtive to be widely utilized and will inevitablely be the trend of automotive lighting technology. However, high power LEDs are all faced with the problem of high junction temperature, which lead to the alternation of the wavelength, the decrease of the optical efficiency even the shortenness of life span. Thus, the heat dissipation problem is one of the main reasons that affect the application of LEDs. An efficient, reliable refrigerating technology is really a tough problem to be solved in LED industry.A thermal managing method of LED headlamps based on the EHD is presented aiming at the shortages of current cooling methods. The EHD refrigerating test system was designed and built to lead the test on LED headlamp.The research shows that:(1) Corona discharge phenomenon and electrical properties are preliminary studied, which laid the theoretical foundation for the follow-up experiments. Negative corona discharge is more quiet, steady than positive corona discharge, generating higher corona current at the same voltage; the threshold voltage of negative corona is lower than that of positive corona, corona current and the voltage meet Townsend discharge relation, namely the square root of corona current is linear change relationship with the discharge voltage. The negative corona discharge refrigerate LED chips at lower voltage,obtaining a better heat dissipation performance,compared with positive corona.(2)Effects of discharge voltage, electrode polarity, LED chip input power, net electrode number, electrode array and discharge gap on the heat dissipation performance of the device are studied through the test comparison; the structure of EHD device is optimized to obtain the optimal scheme of heat dissipation device;The system achieves the best heat dissipation performance while the discharge distance is 10 mm, the corona power is 1.5W, with the 1 x 11 array #20 net and negative corona discharge.(3)Optimal heat dissipation scheme is applied on the cooling test in simulated automobile headlamp working conditions, and the possibility of EHD cooling method is verified through the comparison with piezoelectric fan. EHD cooling system achieved a better cooling performance close to the piezoelectric fan. EHD cooling device has the advantages of no vibration, low noise, high efficiency, energy saving, reliable and durable, compared with the currant heat radiation methods.