LED lighting quality and drive power relationship
LED is the English "LIGHTEMITTINGDIODE" abbreviation, the Chinese abbreviation of light-emitting diodes, because it has environmental protection, long life, high photoelectric efficiency (the current light efficiency has reached 100LM / W), seismic and many other advantages in recent years in various industries to develop rapidly , Theoretically, the LED life of 100,000 hours or so, but in the practical application process, some LED lighting designers on the LED drive power or lack of choice or improper pursuit of low cost, the results of LED lamp product life greatly shortened, Poor LED lamps life of less than 2000 hours, and some even lower, the results of the advantages of LED lamps can not get a good play.
Due to the special nature of LED manufacturing, resulting in different manufacturers and even a manufacturer in the same batch of products produced by the LED current and voltage characteristics are greater individual differences. Is a high-power 1W white LED typical specifications, for example, in accordance with the LED current and voltage changes to do a brief description of the general application of 1W white light forward voltage of 3.0-3.6V or so, that is, when the nominal 1W LED In the flow of 350 mA current, it may be at both ends of the voltage at 3.1V, may also be 3.2V or 3.5V may also be other values, in order to ensure the life of 1WLED, LED manufacturers generally recommend lamp factory with 350mA Drive, when through the LED at both ends of the forward current to 350 mA, the LED at both ends of the increase in the forward voltage is very small, will make a significant increase in LED current forward, so that the LED temperature in a straight line to accelerate the LED light failure , So that LED life shortened, even when the bad burn LED. As the LED voltage, current changes in the particularity, so the power supply to the LED put forward stringent requirements.
LED drive power is the key to LED lighting, it is like a person's heart, to create high-quality, for lighting LED lamps must give up constant pressure way to drive LED.
Many high-power LED packaging plants now combine a number of individual LEDs in parallel and in series to produce a single 20W, 30W or 50W or 100W or higher power LED, although these individual LEDs Are strictly selected and matched, but because of the internal number of dozens of small, as many as hundreds of single LED, so after packaging high-power LED products in the voltage and current is still very different, and phase Than a single LED (generally single white, green, blue working voltage at 2.7-4V, single red, yellow, orange light working voltage in the 1.7-2.5V) parameter difference is greater!
At present, many manufacturers of LED lamp products (such as fence, lamp cup, projection lamp, garden lights, etc.), the use of resistance, capacity step-down, and then add a regulator diode regulator, to the LED power supply, There is a great drawback, first of all low efficiency, in the buck resistor on the consumption of large amounts of electricity, and even may exceed the power consumption of the LED, and can not provide high current drive, because the greater the current, the power consumption in the buck resistor The greater the failure to ensure that the LED current does not exceed its normal working requirements, the design of the product will be used to reduce the voltage across the LED to drive, so at the expense of the expense of LED brightness. The use of resistance, capacity step-down way to drive LED, LED brightness can not be stable, when the power supply voltage is low, LED brightness becomes dark, power supply voltage is high, LED brightness brightened. Of course, resistance, capacity and step-down way to drive the biggest advantage of LED is low cost, so there are still some LED lighting enterprises in this way.
Some manufacturers, in order to reduce the cost of the product, the use of constant voltage drive LED, also brought the production of each LED light intensity uneven, LED can not work in the best condition and a series of questions
Constant current source drive is the best way to LED drive, the use of constant current source drive, do not have the output circuit in series current limiting resistor, LED current flowing through the outside power supply voltage changes, ambient temperature changes, and LED parameter dispersion Affect, so as to maintain a constant current, give full play to the various excellent LED characteristics.
LED constant current power supply to the LED lamp power supply, due to power during the work will automatically detect and control the current flowing through the LED, so do not have to worry about the moment in the power there is too high current through the LED, do not have to worry about the load short-circuit burn Bad power supply.
Using constant current drive mode, it can avoid the LED forward voltage changes caused by current changes, while constant current to LED brightness stability, but also easy to implement LED lighting factory to ensure high-volume production consistency, so many manufacturers have Fully aware of the importance of the drive power, many LED lighting manufacturers have to give up constant pressure, and the use of a high cost of constant current way to drive LED lamps.
Some manufacturers worry that the power supply board selection of electrolytic capacitors will affect the life of the power supply, in fact, is a misunderstanding, such as: If the choice of 105 degrees, life of 8000 hours of high-temperature electrolytic capacitors, according to the passage of electrolytic capacitor life estimation " , Life expectancy is doubled ", then it is working in the 95-degree environment for 16,000 hours, in the 85-degree environment working life of 32000 hours, 75 degrees in the working life of 64,000 hours, if the actual working temperature is lower, Then the life will be longer! From this, as long as the choice of high-quality electrolytic capacitors on the drive power life is no impact!
There are a bit worthy of LED lighting business Note: As the LED process will release a lot of heat, so that the die junction temperature rise rapidly, LED power higher, the greater the heat effect.LED chip temperature will lead to light-emitting device performance And the luminous flux drops by 3%, so LED lighting must pay attention to the LED light source itself, the heat dissipation work, in the case of possible, the LED light source itself, Try to increase the LED light source's own cooling area, try to reduce the LED's own operating temperature, if conditions permit, it is best to power part and the light source part of the separation, blindly pursue a small volume and ignore the lamp and power supply operating temperature is not desirable of.