Why does the LED drive power supply need aluminum electrolytic capacitors?

[Ancient China Aluminum Network] An important reason for the low life of LED driver power supply is the insufficient life of the aluminum electrolytic capacitor required for driving the power supply. The main reason is that the ambient temperature inside the LED lamp is high during long working hours, resulting in aluminum electrolytic capacitors. The electrolyte is quickly depleted and its life is greatly reduced. Generally, it can only work for about 5,000 hours. The life of the LED light source is 50,000 hours, so the working life of the aluminum electrolytic capacitor becomes a short rib of the life of the LED driving power supply.
Now some vendors have solved this problem by inventing a LED driver solution without aluminum electrolytic capacitors. However, not all LED driver power suppliers agree with this approach. Chen Hao pointed out: "There is currently no one in the LED lighting drive power supply that is currently in mass production. The drive scheme for electroless capacitors is used because without it, many test standards cannot be passed, such as EMI test and flicker-free test."
The use of aluminum electrolytic capacitors LED drive power scheme is easily the above test, if replaced by film capacitors and ceramic capacitors or tantalum capacitors, what is the situation? The film capacitor must reach the same capacitance (usually 100-220uF), the volume will be very large, and the cost is too high, the ceramic capacitor is generally too small, such as the use of multiple ceramic capacitors to achieve such a large capacity, the board area And the cost is too large, tantalum capacitor to have such a large capacity, one is too expensive, but the pressure is too low to meet the requirements, so replaced by any other kind of capacitor, is basically not too bulky, or too expensive, If these disadvantages are replaced by capacitors with small capacitance, the effect of eliminating ripples is not so good. Many of the strict certification test indicators required for export products cannot pass. Therefore, high-quality LED driving power is still commonly used in aluminum electrolytic capacitors. .
Many suppliers claim that the electrolytic capacitor-less LED driver power supply solution is likely to only remove the aluminum electrolytic capacitor at the AC input, and the aluminum electrolytic capacitor at the constant current output should be difficult to remove or replace.
NXP has introduced a TRIAC dimmable 13W LED bulb with an embedded driver power supply. The SSL2102-based driver solution uses aluminum electrolytic capacitors. When I asked about the working life of the lamp, the working life of the aluminum electrolytic capacitor will definitely affect the life of the entire LED bulb, but you can take some physical methods to alleviate this problem, such as the aluminum electrolytic capacitor on the pcb close to the lamp At the end, in general, the temperature of the part closer to the LED light source is higher and can reach 100-200° C. The heat dissipation metal shell part is secondarily, generally about 100° C., and the tail part is relatively low, generally about 70° C. The location of the aluminum electrolytic capacitor close to the lamp tail, its life will not decay too much. Our experiments show that its life span can reach about 10,000 hours, which is equivalent to 10 years of use time. This is basically acceptable for general home users.
From the perspective of the LED drive power supply structure, Chen Hao said that Japan and the United States will mainstream non-isolated solutions because their power grid input voltage is only 110V. In China and Europe, an isolated solution will be the mainstream, because their grid input voltage is as high as 220V, and the security of the isolation scheme is guaranteed, although the cost may be higher.

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