Industry news

2016August

Talking about the LED fluorescent lamp power supply design several key

From: www.szbako.com Data:06/08/2016

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at present, LED fluorescent lighting in the market is relatively active, LED driver power supply manufacturers are mainly divided into three types:
first is development of LED chips and LED lamp factory, homeopathic downstream penetration;
of the second kind is had to do is to do ordinary lighting factory;
the third class is completely new factories, they used to do power supply or other products or new venture. LED LED fluorescent lamp power is a very important part of the
fluorescent lamp, if the choice is not properly, LED fluorescent lamp can not play his due performance, and even may not be able to use normal lighting. Below I LED fluorescent light made some small suggestions, for your reference.
1, LED fluorescent lamp power why must the constant flow of it? LED
semiconductor characteristics determine its environmental impact is greater, such as temperature increases, LED current will increase; voltage increase, LED current will increase. Long term more than the rated current, will greatly shorten the life of the LED. And LED constant current is in the temperature and voltage and other environmental factors, to ensure that the current working current is constant.
2, LED fluorescent lamp power supply to be able to match with the light board?
some customers first design panel lights, to find the source, found it difficult to have a suitable power, or current is too large, the voltage is too small (such as I> 350mA, V <40V); or current is too small, the voltage is too high (such as I <40mA, V> 180V), caused by the result is severe fever, low efficiency, or input voltage range is not enough. In fact, choose one of the best in the series and the way, plus the voltage current on each LED is the same, and the effect of the power supply can play the best performance. The best way is to first and power manufacturers to communicate, tailored.
3, LED fluorescent lamp power supply current is how much is the most appropriate?
General led rated working current of 20 mA Pei, some factories start is used to do, 20 milliampere design, in fact, this current work fever is very serious, the multiple comparison test, designed to 17 ~ 19 Ma Pei is ideal, design recommendations for 18 milliampere.
4, LED fluorescent lamp power supply voltage is how much?
general LED recommended operating voltage is 3.0-3.5V, the test, most of the work in the 3.125V, so the 3.125V calculation is more reasonable. Series parallel and wide voltage voltage =3.125*M
M lamp series, LED lamp panel 5 is wide?
to make LED fluorescent lamp work in the input voltage range of a wide range (full voltage) AC85 ~ 265V, the light board LED series parallel way is very important. As the current power supply is generally non isolated buck power supply, in the requirements of wide voltage, the output voltage should not exceed 72V, the input voltage range can reach 85 ~ 265V. That is, a series of not more than 23 series. Parallel number not too much, otherwise the work current is too large, serious fever, recommended for 6 and /8 and /12. The total current is not more than 240 ma. There is a wide range of voltage programs, is to use the L6561/7527 to raise the voltage to 400V, and then buck, the equivalent of two switching power supply, the cost of your one times, this program is not high price, no market.
6, LED series parallel connection with the PFC power factor and the wide voltage of the relationship is what kind of?
the current market of power factor correction (PFC) have three: without special PFC circuit a, the PFC generally at about 0.65; a is with passive PFC circuit, lamp panel horse was well PFC general around 0.92; also used a is made of an active 7527/6561 circuit PFC can reach 0.99, but the cost is the second scheme is one times more expensive than. So many of the second programs. For passive PFC circuits: also known as the valley fill type PFC circuit, the operating voltage range is half of the peak of the AC input voltage. If the input is 180V, the peak is 180*1.414=254V, half of the peak voltage is 127V and then minus step-down pressure 30V, the maximum output is 90V, so the LED lamp series number 28 on. Therefore, in order to obtain the relatively large power factor, beads series number can not be too much. Otherwise, it is not up to the requirements of low voltage.
7, LED fluorescent power supply constant current accuracy is the most suitable?
market, some of the power of the constant current accuracy is too poor, like the popular PT4107/HV9910/BP2808/SMD802 program on the market, such as constant current solution, the error is up to + 8% or + 10%, constant current error is too large. General requirements in + 3% on it. According to 3% of the error, 6 parallel, each error is about 0.5%, if it is 12 parallel, each error is about 0.25%, the accuracy is enough. Accuracy is too high, the cost will be greatly increased. And in terms of LED, 17 Ma and 17.5 Ma training is not affected.
8, isolation /non isolated
in general, such as isolated power supply 15W, put in the LED tube, the transformer is a large volume, it is difficult to put into. Especially for T6/T8 tubes, almost impossible, so the general isolation can only do 15W, more than 15W, and the price is very few, and the price is very expensive. So the isolation of the price is not high, generally non isolated accounted for more mainstream, the volume can be made smaller, the minimum can achieve high 8 mm, in fact, non isolated security measures well, is not a problem.
9, LED daylight lamp power efficiency
output power (the output voltage of LED * output current /input power). This parameter is very important, if low efficiency means that the input power have a large part of the conversion of heat emitted; if it is installed in the lamp will produce a very high temperature, plus we led a luminous efficiency than the radiating heat, the stack will be produced more high temperature. And our internal power supply all electronic parts of life will be with the rise in temperature reduced. So the efficiency is decided by the life of power supply is the most fundamental factor, efficiency can not be too low or consumption in power supply of heat is too large. Generally above 80% can be, however, the efficiency and the lamp board matching connection method.
10, LED fluorescent lamp power supply size
height is the major limiting factor, generally used for T6 tube /T8 size requirement height is not too high, less than or equal to 9 mm. T10 tube height less than or equal to 15 mm. Length can be long, more easy to heat.

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