Long life - outdoor LED lighting driver power supply design China lighting network

Outdoor lighting, especially for street light, tunnel light maintenance is difficult, high cost, so the LED driver power supply for these applications need not only high reliability and high protection grade, it will be a long service life, the lamps and lanterns can run for at least 5 years. This article introduces how to make sure the LED drive power long life. LED driver is composed of semiconductor, capacitor, potting glue, PCB, magnetic device consisting of hundreds of components such as products, including electrolytic capacitor is considered to be the weakest link. Therefore, when calculating the LED the life of the drive, we should find A, B and C capacitor in the life of the shortest one. Below is a formula calculating the service life of electrolytic capacitor k is by the capacitance of the RMS ripple current and working voltage decision factor, it can serve as a value, also can be used as a function. L0 is provided in the specification of the life value. Ts for capacitor rated shell temperature, average is 105 ℃. Tc is the working temperature of condenser. Maybe there are other need to compute formula, but this is the easiest way to illustrate the relationship between the life and the several key factors. Then according to the theory, we need to do the following several key steps to do a long life of the drive power supply. Select long-life capacitor, ensure L0 good enough. Utility power of choice is 10000-12000 hours @ 105 ℃ NCC and Rubycon brand service life. Choose Japanese capacitance, long life, high quality, in a cold environment also can keep good work performance, even under - 40 ℃ could keep good work performance. High efficiency, good thermal conductivity. When the temperature lower 10 ℃, the capacitors of life by a factor of 2. To reduce the power consumption of the LED driver power supply means less heat. Assuming power loss is the same, so the quantity of heat through the air or exits through the lamps and lanterns is very important. Most of the heat is by pouring sealant and shell conduction, which is why these LED drive power supply adopts the high thermal conductivity glue and thick aluminum shell. Ripple current. When people talk about life, ripple current is always be ignored, but it plays a key role in the calculation. When we examine a capacitance of the specification, we see is the life of a 10000 - hour @ 105 ℃ and specify the ripple current. The ripple current, the greater the capacitor itself more heat. Therefore, if the ripple current is larger, internal temperature of the condenser will be much higher than the shell temperature, life will reduce. Compared with competitors, these larger capacitance is used to achieve lower current ripple. This is why these LED the life of the drive power supply in 75 ℃ can reach 100000 hours. After knowing how to design long life LED driver, we need to know how to use it. This is a typical lifespan and shell temperature curve, we from the icon under different shell temperature can be calculated in the power of life. There is a very important of the definition of 'life end', we think that 10% failure rate is usually 'life end. Below is the NCC capacitance in the manual about the curve of failure rate and time. To sum up, the design of long life LED drive power supply is not so simple. High quality components and experienced engineer's excellent design is the key factor for achieving this goal.

YanZhiXiang

utility power supply