Fully understand the LED heat dissipation problem of LED lighting

Fully understand the LED heat dissipation problem of LED lighting

The most critical parts of an LED lighting product are heat dissipation, drive power, and light source. At the same time, heat dissipation is particularly important. The heat dissipation effect directly affects the life quality of lighting products, and the life of the drive power itself. And the stability of the output current and voltage also has a great impact on the overall life quality of the product. The light source is the core part of the entire product. The heat dissipation will be analyzed and explained below.

Questions and answers about heat dissipation of LED lighting fixtures

For the current common incandescent bulbs or fluorescent lamps, even if the product itself may generate thermal energy, the high heat of the components can still be effectively isolated, so that the light source and the power socket will not cause unexpected problems due to heat. However, solid-state lighting is different. Once the LED components are concentrated at a single point of high temperature operation, more positive measures must be taken for heat treatment, and at the same time, active and effective heat treatment mechanisms can be used to avoid problems with the lamps. The heat treatment of LED solid-state light source is much more complicated than traditional lamps.

Traditional light sources or lamps often have the problem of generating high heat during operation, such as halogen bulbs or incandescent bulbs. If they are in the form of incandescent lamps, the tungsten wire is heated in a specially treated lamp bulb to produce light.

In fact, the high temperature is generated on the filament rather than the lamp holder. Even though the lamp holder will indirectly generate high temperature due to the radiant heat and heat conduction of the lamp bulb glass or metal due to the tungsten filament, the generated temperature is within the acceptable safe range. Coupled with indirect contact conduction, the safety is relatively high.

However, if the lamp is replaced by a solid-state LED light source, its heat treatment may become a new application safety issue. Most people think that LED has the advantages of high energy conversion efficiency and low driving energy, and it is naturally safe to use. However, in order to achieve the purpose of daily lighting applications, LED solid-state light sources must strengthen the unit by increasing the power of a single group of components The output lumens of the device, for example, the lamp factory will adopt the integrated form of multiple LED components to enhance the output effect, and the simultaneous operation of multiple components can also improve the problem of the LED solid-state light source light type biased point light source, so that the LED solid-state light source technology can produce lamps like bulb Surface light effect.

If you want to strengthen the output lumens of the unit, you must have a higher current to make the PN junction of the LED chip produce more lumens, but the higher current will also make the temperature of the single-point LED component increase and more difficult to handle, even for Improving the light performance and luminous efficiency of the lamps and adopting the combination of multiple components will also aggravate the high temperature problem of the LED lamps and make the heat dissipation problem more difficult to deal with.

Looking at the current development trend of the LED lamp market, most manufacturers of LED light sources will first dominate the market, because of the high unit price and high profit, they can also quickly enter the development of more advanced LED light source markets through technological differences. For example, for Downlights, wall lights, and ceiling lights for interior decoration and situational lighting applications have become a more common design form of LED light source lamps. The power saving benefits of replacing traditional lamps are also the most concerned by related companies.

LED light source lamps must focus on the thermal management design. In the case of recessed lamps, wall lamps and ceiling lamps that may be used in closed or semi-closed life cycles, they pose more stringent challenges. Lamp developers must focus on materials, product configurations, and main / Passive heat dissipation mechanism, driver chip design and other aspects to invest more resources to avoid product problems. In particular, LED embedded lamps are small in size, and often adopt multi-component integration, and the heat dissipation design of the module is more difficult. The embedded lamp housing adopts aluminum extrusion or heat sink design, which can play the role of self-heat dissipation. But this is not enough.

LED thermal management: NTC continuous operating temperature maintains the safety of LED lights

If the LED lamps are not equipped with sufficient thermal management design, the life of the lamps may be drastically reduced due to frequent high heat operation during the use process, resulting in the trouble of frequent replacement of faulty LED lamps. Serious cases may even cause accidents due to high temperatures. Cause the line or surrounding decoration to burn!

In the product development stage, intelligent LED lighting control technology can be used to actively monitor the temperature performance of the LED lamps and the overall light source module to simplify the thermal management of the device. At the same time, when the temperature of the lamps and surroundings rises to the section, The lamp must reduce the electric power and reduce the LED brightness output, so as to improve the safety of the LED solid light source lamp.

Consider the simpler design form of the LED ceiling lamp housing. If the driver function used by the lamp itself is more focused on power conversion and LED component driving, there is no built-in temperature control microprocessor and heat dissipation processing module. The cost of LED lamps can be integrated with NTC (NegaTIve Temperature Coeffient) negative temperature coefficient ThermistorSensors electricity, which is a relatively cost-effective safety design solution.

The so-called NTC electricity is designed to monitor the temperature of the LED module lamps through electronic backing, through the default temperature warning or corresponding automatic processing of driving conditions, and the method of turning off the LED solid-state light source module to improve the safety of LED lamps. At the same time, NTC electricity can also reduce the complexity of the design.

Because the temperature coefficient of NTC electricity is very large, it can detect and detect small temperature changes, and is widely used in related electrical designs that require measurement, control, and temperature compensation. NTC electricity is basically used in the design of LED light source modules. The above is to measure the surrounding temperature change of LED solid-state light source lamps and lanterns. As for the measurement status, the current status of the voltage will change with the NTC, and the corresponding relationship between the voltage and the temperature of the NTC electricity is directly measured.

When the temperature of NTC and peripheral power or the entire module rises, the resistance of NTC power will decrease immediately, and the product can feedback the relevant safety control mechanism according to this dependency, such as reducing the driving current of LED light-emitting components or directly forcibly turning off the lighting of the lamp. After the temperature problem is improved, the lighting status is automatically restored, thereby obtaining the safety of the lamp.

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