1. Introduction:
In the factory's energy consumption, lighting energy consumption occupies a certain weight. For example, in a factory building of 40,000 square meters, the lighting power load is about 400KW. Therefore, how to achieve energy saving and environmental protection in the selection of factory lighting is an important topic for factory designers. In addition to energy saving and environmental protection, the lighting fixture based on the new LED light source has the advantages of long life, fast response time, and pure light color. In recent years, it has been widely favored by consumers.
2. Key technology of LED lighting design
New technologies, new materials and new processes have been continuously applied to the design of high-power LED light sources, laying a solid foundation for the design of high-power LED lamps. Because the same LED light source applications are very different, their design, testing and other standards The introduction of LED lamps has a certain lag, which leads to poor interchangeability of products produced by different manufacturers in terms of structure and performance. At the same time, LED lighting products themselves are an integration of mechanical, optical, and electrical factors, and their design is even more involved. Technologies in many fields.
3, LED high bay light design
3.1 Power selection
Traditional high bay lamps are mostly 250W or 400W high pressure sodium lamps and metal halide lamps. Compared with the characteristics of new LED lamps, there are obvious differences, see the following table:
Considering the problems of high pressure sodium lamp and metal halide lamp decay and secondary light emission in actual use, the actual luminous efficiency is much lower than 80lm/W, which often fails to reach the nominal 70%. Based on this, the power of the LED high bay light we developed for the first time is set to about 120W. Once the lighting effect meets expectations, it will save more than 50% of energy than traditional lamps.
3.2 Light source selection
At present, the more well-known brands of high-power LED light sources on the market are: CREE, OSRAM, NICHIA, Lumileds (the earliest LED), in addition to Taiwanese manufacturers Epistar, Addison, and domestic packaging manufacturers Shenzhen Wanrun, Zhuhai Ruifeng, Jiangxi Lianchuang, etc. are also popular brands.
In order to ensure the stability of the product, we use the most well-known CREE light source for this industrial and mining lamp.
3.3 Heat dissipation design:
In high-power LEDs, heat dissipation is a big problem. For example, if a 10W white light LED has a photoelectric conversion efficiency of 20%, 8W of electrical energy is converted into heat. If no heat dissipation measures are taken, the core temperature of the high-power LED will rise rapidly, when its junction temperature (TJ) When the temperature rises above the maximum allowable temperature (usually 150°C), the high-power LED will be damaged due to overheating. Therefore, heat dissipation design is also our most important content. In the following, we will discuss heat dissipation design from the combination of aluminum substrate and heat sink.
3.3.1 Board selection
In the application of LED products, it is usually necessary to assemble multiple LED light sources on a circuit substrate. In addition to the circuit substrate playing the role of carrying the LED module structure, on the other hand, as the output power of the LED becomes higher and higher, the substrate must also play the role of heat dissipation to transfer the heat generated by the LED crystal. Therefore, the material selection Must take into account the requirements of structural strength and heat dissipation. For the substrate, we compared FR4, ceramic substrate and MCPCB respectively.
(1) The thermal conductivity of FR4 is about 0.36W/m•K, which cannot meet the heat dissipation requirements of high-power LED lighting;
(2) Ceramic thermal conductivity is greater than 80W/m•K, which is expensive and poor in processability, and cannot be used in a large area;
(3) MCPCB thermal conductivity is greater than 2.0W/m•K, moderate price, strong processability, mature technology and mass production.
3.3.2 Radiator design
The role of the radiator is to absorb the heat transferred from the substrate or chip, and then dissipate it to the outside environment to ensure that the temperature of the LED chip is normal. Most radiators are carefully designed to be suitable for natural convection and forced convection. Namely active radiator and passive radiator. Their respective performance characteristics are shown in the following table:
Considering cost and stability, we choose passive cooling. Passive radiators are classified into Al Extrusion radiators and Al Die-Casting radiators according to their materials. The respective characteristics are as follows:
Regarding the use of Heatpipe&Fin&Vapor-Champer on the Heat sink, after testing, the emitter temperature does not drop much. According to the stability requirements of the engineering lamp, it is not considered for use.
3.4 Mechanism design
Mechanism design involves not only the mechanical structure of the entire lamp, but also the beautiful appearance of the lamp. Next, we carry out the specific design of the die-casting radiator from the following four aspects.
A. Best Look
Regarding the appearance, we envisioned the following two forms.
C. Best Thermal
The heat dissipation performance of the radiator is largely determined by the mechanical design of the radiator. The material is the same as ADC-12 die-cast aluminum. When the heat sink has different parameters such as the outer diameter, the height of the fin, and the density of the fin, the heat dissipation performance may be far different. During the design process, we selected four different radiators with different structures, and simulated their heat flow, as shown in the figure below
Through heat flow simulation, we found that Case4 has the best thermal performance. The following table:
At the same time, we can draw the following conclusions:
(1) Reduce the height of Fin while increasing the outer diameter of the Heat sink to get a more effective heat dissipation effect.
(2) For the Heat sink of the same weight, increasing the height can achieve a more effective heat dissipation effect than increasing the diameter of the radiator.
(3) Case4 Thermal is the best, we increase the outer diameter of the radiator by reducing the height of Fin, and get the best radiator under the condition of the same cost.
4, LED high bay light verification results
In order to ensure the quality of the lamps, we have carried out a series of tests on light distribution, Thermal, electrical safety, and reliability before mass production and shipment. The following are the verification results of each test.
5. Cost and benefit evaluation
As we all know, compared to high-pressure sodium lamps or metal halide lamps for plant lighting, the initial investment cost of LED high bay lamps is obviously much higher than that of traditional lamps. However, because the LED light source has the characteristics of high luminous efficiency, and when it is made into a lamp, the advantage of the strong directivity of the LED light source is easily reflected. The efficiency of the LED lamp is much higher than that of the traditional lamp, so its energy-saving characteristics can be Obviously manifested. The following table is an investment benefit analysis of our 120WLED high bay lamp and traditional 400W high pressure sodium lamp.
6. Conclusion
This LED high bay light has undergone many modifications and improvements from the initial design stage to mass production shipment. Among them, through timely communication and close cooperation between R&D engineers and business departments, the product quality and appearance have been better recognized by the market. There are also many design details, such as the selection of Grease, the treatment of the waterproof ring, the improvement of the PC cover, the selection of the power supply, etc., are always in continuous improvement. As for a more reasonable and exquisite design plan, readers are also welcome to let us know. Thank you
