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Environmental issues have become a extremely important thing in the economic development of every country. LED lighting because of energy-saving feature has become new favorite in the lighting industry. We all know LED lighting features with high efficiency, long lifespan and cost-effective. LED lighting has a broad application prospect and market.
However, the problem of heat dissipation of high-power LED luminaires such as stadium flood light, large plaza flood light, airport tarmac flood light and Port cargo center flood light etc limits the development of high power LED lighting industry. If the problem of heat dissipation is not solved, the temperature of LED lighting fixtures will rise, leading to the decrease of its light efficacy and service life. We will cover the method and technology of reducing the temperature rise of high-power LED flood lights and temperature control from two aspects, lighting fixture itself and driver selection in this paper.
1. Reduce the temperature rise
Currently heat dispatch methods of led flood light mainly include natural convection heat dissipation, blower dissipation, heat pipe and loop heat pipe etc.
1) Separate power driver from led flood light
Because power driver originally will generate a certain amount of heat itself, which will increase the quantity of heat inside led luminaires. Adding up the heat that spill out of led lighting fixtures themselves, the temperature inside lighting fixture will be up to a quite high degree. At the same time, designing power driver and lamp all in one will make entire led lamp in an uneven temperature environment for long time. That is the end that close to the power driver will hotter than the end away from the driver. All these factors will lead to damage and early light decay of luminaires, which will affect the service life of lighting fixture.
The following picture shows the variation curve of temperature inside of led flood light with working time. T1 is the temperature at the place where driver is placed; T2 is the temperature at the place far away from driver; and T3 is the temperature at the center of light.
When light and driver are all in one, T1 is far higher than T2 and T3 , that is , the temperature around driver is far higher than the temperature of light center and place where far away from power driver as working time goes on.
While lamp separates from power driver, the curves of T1 and T2 coincide.in other words , the temperature around the driver is the same as that of place far away from driver. T3 is slightly higher than T1 and T2 and the difference between them are not significant. The whole lamp, we mean inside of fixture, is in a stable, low and relatively even temperature state. This shows, the temperature distribution of the whole lamp is very uniform when light and power driver are installed separately.
2) Choose high quality LEDs
The selection of LEDs also plays a key role in reducing the temperature rise. LEDs encapsulated by a material with high thermal conductivity and consistency can improve the internal heat dissipation property. adopting metal substrate with high thermal conductivity and high heat dissipation as the base tab of LEDs make heat dissipation symmetrical so that can maximize the performance of heat dispatch.
3)enlarge the heat radiating area
In addition, we can also increase the heat dissipation area of the heat sink, design a heat sink with better heat dissipation performance, and deform the structure of the heat sink to enhance the heat conduction efficiency.
2. Control temperature via power driver selection
When led flood light is working at rated power, the generating heat exceeds its heat dissipation capacity. Besides the method we mention above, we also can select temperature controlled power driver to limit the temperature rise. When the temperature reach some tipping point ,the temperature control system of power driver starts to work to appropriately reduce the output of the driver to achieve the purpose of limiting and reducing the temperature rise.when the temperature decreases, led flood light restores the original working state.
1) The theory of constant current power drive controlling temperature rise
Constant current power driver realize the temperature control of the LED flood light by controlling the output current of the drive .the following picture show the theory of temperature control. The constant current is output to the high power led flood light through the power driver. The heat generated by LEDs is conducted to heat sink by good thermal conductive materials and finally dissipates into air .
when environment outside goes against the heat dissipation , the temperature of LEDs will gradually reach the setup temperature of the temperature control system. The constant current power driver of led flood light will reduce current output after getting feedback, so that achieve the goal of limit and decrease the temperature rise of LEDs.
2) The theory of constant voltage power drive controlling temperature rise
The constant voltage power driver controls the output voltage of the driver to realize the control of LED flood light.It is roughly similar to the constant current driver. the difference is the controlled factor and temperature control system circuit .
In the circuit signal transmission system, Rs is a positive temperature coefficient temperature sensitive resistor; R1, R2, Rx are ordinary resistors. And they work together to adjust the output voltage of power driver to achieve purpose of reducing temperature rise. The circuit signal transmission system is placed closely to LEDs to sense the temperature.
Through two methods above, we can effectively reduce the temperature rise of high power LED flood light. Once the temperature rise surpassing the set temperature, the power driver will reduce current or voltage output under the condition of not affecting use so that avoid lighting decay happening by the overheat and service life shortening.
More led flood light information here: https://www.agcled.com/products/led-flood-light/?from=blog
