How to reduce the temperature rise of high power LED flood lighting?
Environmental issues have become a top priority in the economic development of various countries, so the LED lighting with energy saving and power saving has become the “new darling” of the lighting industry.
Because LEDs have higher luminous efficiency and lower manufacturing costs, their application prospects and markets are very large. However, the heat dissipation problem of high-power LED lamps limits the development of the LED lighting industry, and the heat dissipation problem cannot be solved, which will increase the temperature of the LED lamps, resulting in a decrease in luminous efficiency and a shortened service life.
This paper proposes methods and techniques for reducing the temperature rise and temperature control of high-power LED lamps from two aspects of the design of lamps and drivers, effectively reducing and limiting the temperature rise of high-power LED lamps.
1 Reduce the temperature rise
At present, the heat dissipation methods of LED lamps mainly include natural convection heat dissipation, installation of fan forced heat dissipation, heat pipe and loop heat pipe heat dissipation.
1.1 Power supply and lamp body separation
Since the power source itself generates a certain amount of heat, the source of heat on the LED lamp increases. At the same time, the integrated design of the power supply and the lamp makes the overall illumination of the LED lamp uneven, and these factors will cause fatigue and early failure of the luminaire, which will affect its life.
Figure 1 shows the curve of LED lamp temperature with working time. In the figure, T1 is the temperature at which the power supply is placed, T2 is the temperature away from the power supply, and T3 is the center temperature of the lamp body. It can be seen from the figure that with the increase of working time, T1 in Fig.
1(a) is much larger than T2 and T3; in Fig. 1(b), the two curves T1 and T2 coincide, and T3 is slightly larger than T1 and T2. It can be seen that after separating the power supply, the temperature distribution of the whole lamp is very uniform.
1.2 Select high quality LED module
The choice of LED modules also plays a more important role in reducing temperature rise. Selecting an LED lamp bead that is encapsulated in a material with high thermal conductivity and uniformity can improve internal thermal diffusivity.
The metal substrate with high thermal conductivity and high heat dissipation is used as the wick board to make the temperature distribution of the heat sink uniform, so that the heat dissipation effect is maximized.
1.3 Increase the heat dissipation area
There is a gap at the interface between the aluminum substrate and the heat sink, and the thermal conductivity of the air is small, only about 0.03 W/m·K, so that the contact surface can be coated with a gel-like thermal grease having a high thermal conductivity to increase Actual contact area. At the same time, the heat dissipation area of the heat sink is increased, and the structure of the heat sink is deformed to facilitate heat dissipation.
2 temperature control system
When the heat generated by the LED lamp at rated power exceeds its heat dissipation capacity, this paper also uses temperature control technology to limit the temperature rise while enhancing heat dissipation.
At high temperatures, the temperature control system starts to work, appropriately reducing the output of the driver, reaching the limit and reducing the temperature rise; when the temperature is lowered, the original working state is restored. The following two ways to drive the LED light are selected.
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