Positive thinking on how to improve the reliability of LED road lighting
Xinyuan Sheng Technology Co., Ltd. Technical Director Guan Xinning Ph.D.
In recent years, under the global environmental protection trend, the LED lighting industry has risen rapidly. Many technology companies have invested in this emerging industry. However, due to the failure of the LED lighting reliability performance standards to be set and properly regulated, a large number of products cannot pass the test and severe light. The main reason for the decline is that no theoretical research is designed to examine the pillars, thus causing doubts about the use of the owners, and thus delaying the opportunity for industrial development. LED lighting solutions supplier, Xinyuan Sheng Technology (Thermalking), provides high-performance LED street light components to the lighting system's important technical pointer specifications data for industry reference.
The key technology of LED chip and package component luminous efficiency, the key technology of LED chip and package component, European, Japanese and Japanese manufacturers have mass production breakthrough light efficiency of 100~120lm/W, surpassing the traditional highest efficiency HID light source (lighting efficiency) 90~110lm/W), solve the problem that the current LED light efficiency is less than 45lm/W, meet the long life of road lighting, low light decay, meet the international standard average illumination, up to 25~40Lux specifications and energy saving 30~60%.
LED lighting efficiency, temperature rise and life specification key technical indicators, view CREE or Osram LED and other data published by the industry, the chip PN junction operating temperature Tj <75 ~ 85 ° C, to ensure that working above 85% light efficiency The life span is 50,000 hours, and the temperature rise of the chip PN junction to its own thermal pad (Tjs) is between ΔT=6~15°C. In addition, the LED light efficiency is inversely proportional to the operating temperature. Each increase of 10°C will result in The serious consequences of light decay of 3~6% and half of life, and the general propaganda LED can work at 100~125 °C for more than 100,000 hours, but ignore the light efficiency loss under this condition 25~30 The concept of % is a far cry.
LED street light system heat transfer cooling environment temperature key technical part, the operating temperature of such lamp system should not be higher than 85-10=75 °C; Taiwan LED road lamp specification CNS15233, durability test environment temperature is 50 °C, so street lamp cooling system The temperature rise must be less than ΔT ≦ 25 ° C. Taking Xinyuansheng Technology 150W LED street lamp as an example, the heat transfer system temperature rise test is as low as ΔT≦13°C, and its thermal resistance value is Tr=0.08°C/W, while most industry manufacturers design system temperature rise test ΔT≒30~ At 40 °C, the thermal resistance value Tr=0.2~0.26°C/W is calculated. Under the same conditions, the products of Xinyuansheng Technology will increase the life of the products by 2 times and the brightness by more than 15%. In addition, with the Xinyuan Sheng Technology 350W LED luminaire test, the temperature rise of the heat dissipation system can still reach ΔT=15°C, and the thermal resistance value Tr=0.04°C/W.
The key technology of heat transfer and heat dissipation of LED street lamp system, the heat transfer and heat dissipation method of electronic equipment are suitable for low-power natural heat dissipation method. At present, MR16/PAR30 is from 1~70W, and the system temperature rise has reached 30~40°C. If more than 100W still uses the natural heat dissipation method, just like most products on the market, a large amount of aluminum alloy material must be used to increase the thermal conductivity and the large heat exchange area. The volumetric weight is 2, 30Kg, which not only increases the cost of the lamp but also adds the light pole. The risk of safe suspension of the luminaire. The law of natural heat dissipation is to reduce the temperature by using a metal material with a heavier area. The better the effect, but the cost of aluminum alloy material is increased by NT$60-200/kg. Some manufacturers claim that the heat pipe or loop heat pipe can be used. The heat dissipation effect only solves the heat conduction. Whether it is a heat pipe or a loop heat pipe, it has only the function of heat conduction and does not have the function of heat dissipation. To achieve good heat dissipation, it is necessary to use an effective heat dissipation area with a relative wattage, that is, a large area of ​​metal material must be added. To do heat exchange; otherwise, you must use the active forced cooling method used by high-end and high-power products such as industrial-grade high-reliability air-conditioner air conditioners and computer CPUs. The high-efficiency and military-sized small fan life guarantees 70,000 hours. IP65 waterproof and dustproof grade, plus appropriate originals such as heat pipe and heat-dissipating aluminum fins and reasonable mechanism design, the temperature rise of the tested lamp system can be as low as ΔT≦12~15°C, compared with the natural heat-dissipation method. °C, the life will increase by 2 times and the light efficiency brightness will increase by 10~15%.
LED street lamp system reliability, durability environment adaptability test indicators, general LED lamp product design does not consider the dust protection system, outdoor road lamps must completely prevent sandstorms, colloidal suspended matter, gravity dust accumulation in the heat dissipation structure, To avoid the problem of causing the LED to overheat and burn. If the heat dissipation structure faces the surface of the sky and causes dust accumulation, the heat accumulation cannot be dissipated, and LED light decay and burnout may occur. To solve the above problems, it is possible to design a heat dissipation structure to face the ground. Other anti-salt fog tests, etc., Xinyuan Sheng Technology's existing products after 20,000 hours of outdoor testing time, light failure <10%, in good condition. The optical design of the main road lighting can also reach the world standard, that is, the 10 meter high pole must illuminate the long surface of the banner 40 meters on average, and solve the difficult optical lens design to achieve the aspect ratio of 1:4. In addition, the core wick technology module has also achieved light weight, and does not need to rely on the lamp housing as a heat sink. Therefore, the external design of the lamp can be arbitrarily changed in shape to achieve the aesthetic characteristics of each city.
As a high-tech energy-saving lighting industry practitioners must recognize that good lighting heat dissipation includes heat transfer, temperature uniformity, heat exchange and other complex heat transfer traditions based on hard theory, not the LED lights are cold light. Fever, but also seek to solve with a single original or special materials such as noble nanotechnology or aerospace technology. When the terminal customers look at the fog, they must face up to the performance of the LED street lamp. It must have scientific data, theoretical support, perfect system design method as the guideline, good process basis, and finally the test report in the third fair unit. Based on this, it will not happen again and again the vicious circle of light decline goods hindering the development of the industry. Taiwan Xinyuansheng Technology is willing to share the research results and patented technology with the world's peers for many years, including forced heat dissipation and downward heat dissipation. Invention patents such as liquid heat dissipation and dozens of new patents work together to illuminate the world.
In addition, the development of related technologies: current LED chip and packaging technology continue to improve Tj can withstand temperatures up to 100 ° C, life can reach more than 50,000 Hr.... but never change the physical properties of silicon crystal materials "luminous efficiency and Tj temperature rise In inverse proportion, the higher the temperature rise of Tj, the lower the light efficiency. (See Annex 2. Pdf) Cree is marked with 100% light efficiency at Tj=25°C; light efficiency is reduced to 85% when Tj=75°C; When Tj=125°C, the light efficiency is attenuated to 70% (meaning that the newly completed lamps have reached L70 and the light decay is 30%), so the light efficiency and life can not be confused, and the LED factory deliberately emphasizes that their Tj has Can work at 125 ° C life up to 50,000Hr but do not prompt the lighting factory designer to use Tj = 125 ° C as a parameter, immediately lead to 30% light loss, so the world is now committed to breaking through the "heat transfer cooling" key technology for the job Zhi, the lower the temperature drop of Tj, the higher the light efficiency, the longest life under this condition, and the greatest competitiveness.
references:
1. Taiwan LED street light standard CNS15233
2. http://vipweb.url.com.tw/michael.chiang/CREE%20XLamp%20Presentation.pdf
(Annex 46.PDF)
Condition: Blue LED Spec...
L70 (light decay 30%) Tj=65°C Life Time=60,000 Hr.
Tj=85°C Life Time=26,000 Hr.
Tj=70--75°C Life Time=40,000--50,000 Hr.
3. Japan's electronic machine heat countermeasure design Guofeng Shangshu
4. CREE--090211--XLampXP-E 3
5. Arrhenius Law, Arrhenius Law, Law of the Law
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