Analysis of LED lamp power deviation

Recently, various media frequently reported incidents of unqualified quality of LED light sources and LED lamps by national and local quality inspection departments. The high incidence of "quality gate" incidents seriously damaged the image of the company and the brand image of my country's LED industry on the international stage. The situation is alarming.

In the unqualified test items, the actual test power of the lamp and the declared power of the product do not meet a large proportion. As early as 2010, my country has issued the national standard GB/T24908-2010 "Performance Requirements for Self-ballasted LED Lamps for General Lighting" Article 5.3 requires "When the lamp is working at rated voltage and rated frequency, its actual power consumption and rated The difference in power should not be greater than 15% or 0.5W", the International Electrotechnical Commission also requires in paragraph 7 of IEC62722-1 that "the deviation between the nominal value and the actual value of the electrical parameters of the lamp should not be greater than 10%."

The author believes that the reasons for product power deviation are as follows:

First, due to cost pressures, the production process cut corners and cut corners, eliminating the necessary product testing procedures, and the unqualified products were not eliminated in the factory and flowed to the market as shoddy products.

Second, the LED lamp bead has insufficient heat dissipation design margin, the deviation of the assembly process and the incoming materials causes the lamp bead to overheat, and the forward voltage drop (Vf) drops out of control, causing the actual power of the lamp to deviate from the lower limit.

Thirdly, the thermal stability of the optional driving power supply of the lamp is poor, and the temperature drift of the output current is large, which directly causes the lamp power to deviate in a large range.

Fourth, in order to reduce the cost of purchasing LED lamp beads, the lamp bead purchase did not select the LED Vf distribution BIN according to the design requirements, which caused the actual LED power consumption to deviate from the design center value.

Fifth, the optional drive power supply has low constant current accuracy (generally 5%-8%), and cannot be adapted to the various Vf BINs of lamp beads.