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Ten key talks LED fluorescent lamp power supply design - (AddTime :2013-01-09)

At present, the 200W led Flood light market is more active, LED drive power supply manufacturer mainly divided into three types:

Do the first kind is the development of LED chips or LED lights factory, to the downstream, the LED power supply circuit knowledge and 200W led Flood light power knowledge is not much;

The second type is the original do do ordinary lighting factory, everyone into a new products field, a little knowledge of LED power supply circuit, but not much;

The third kind is completely new factory, before they do power supply or other products or new venture, for the LED power supply some understanding, some is not very understanding.

200W led Flood light power supply is one of the 200W led Flood light in very important parts, if improper selection, 200W led Flood light play out his proper performance, and even may not normal lighting use. Below I will 200W led Flood light lighting made some small suggestion, for your reference.

1, why must be constant current 200W led Flood light power supply? Characteristics of LED semiconductor determines its greatly influenced by the environment, such as the temperature increases, the LED current will increase; The increase of the voltage, the current LED will also increase. More than rated current job for a long time, can greatly shorten the service life of the LED. And the LED constant current is in environmental factors such as temperature and voltage change, to ensure the working current is constant.
2, 200W led Flood light power to to be matching with the board? Some customers to design light board, power supply again, find it difficult to have the right power supply, voltage or current is too big, too small (such as I > 350 ma, V < 40 V); Voltage or current is too small, too high (such as I < 40 ma, V > 180 V), the result is caused by heat, low efficiency, or the input voltage range. Actually, choose one of the best string and mode, and the voltage on each LED current is the same, the effect of the power supply, but it can play the best performance. The best way is to communicate with power supply manufacturer, customized.
3, 200W led Flood light current of the power supply is how many is the most appropriate? General LED the rated current of 20 ma, some factories use from the start, design 20 ma, actually the electricity to flow fever is very serious work, by the contrast test many times, designed to 17 ~ 19 ma is ideal, recommend design for 18 ma.
4, how much is the working voltage of the 200W led Flood light power supply? General LED the recommend working voltage is 3.0-3.5 V, the test, and most of the work in 3.125 V, so according to the 3.125 V calculation formula is reasonable. M a lamp bead series the total voltage = 3.125 M Of
5, led lights series with wide voltage more wide? To make the 200W led Flood light work in input voltage range is wide range (all) AC85 ~ 265 v, the light plate LED series way is very important. Due to the power supply is not isolation type of power supply, when demand wide voltage, output voltage not over 72 v, the input voltage range is can reach 85 ~ 265 v. That is, the serial number is not more than 23 string. Parallel number don't too much, otherwise the working current is too big, fever, recommended for 6 and 8 / and / 12 and. The total current is not more than 240 ma as well. Have a wide voltage scheme, which is first with the L6561/7527 voltage up to 400 v, and then step down, equivalent to two switching power supply, cost twice as expensive, this solution ratio is not high, no market.
6, the series of LED and power factor and the relationship between the wide voltage PFC is what kind of?
Of power supply on the market at present there are three kinds of PFC: one kind is without special PFC circuit, the PFC general around 0.65; One with passive PFC circuit, light board horse well prepared, PFC general around 0.92; Still use a is made of an active active 7527/6561 circuit, PFC can reach 0.99, but the cost is more expensive than the second kind of plan of the project. So the second kind of plan. For passive PFC circuit: also called valley type PFC circuit, the working voltage range is half the peak of the ac input voltage. Such as input is 180 v, the peak is 180 * 1.414 = 254 v, half of the peak voltage is 127 v, minus pressure type of differential pressure 30 v, the maximum output is 90 v, so the LED lamp bead series number 28 string. Therefore, to want to get larger power factor, the lamp bead of serial number is not too much, otherwise, just less than the requirements of the low voltage.
7, 200W led Flood light power constant current accuracy how many is the most appropriate? Some poor precision of constant current power supply, on the market like the market popular PT4107 / HV9910 / BP2808 / SMD802 scheme of constant current, + 8% or + 8% error, error of constant current is too large. General requirement in + 3% is ok. According to the error of 3%, and in parallel, each error is about 0.5% of the road, if it is 12 road in parallel, each error about + 0.25%, the precision is enough. Accuracy is too high, the cost will increase greatly. And for the LED, and ma and 17.5 ma.
8, isolation/non - segregation
Commonly isolated power supply such as made 15 w, put inside the LED tube, the transformer size is very big, it is difficult to put in. Especially for T6 / T8 tubes, almost impossible, so the isolation of 15 w, can only do little more than 15 w, and the price is very expensive. So, isolation of not high performance to price ratio, is commonly isolated accounted for more mainstream, can do smaller volume, minimum can be 8 mm high, in fact, not separate safety measures ready, there is no problem.
9, 200W led Flood light power supply efficiency
The power output (LED the * output current/voltage input power). This parameter is very important, if the low efficiency means that a large part of the input power is converted into heat; If it is installed inside the tube can produce a very high temperature, plus we LED a efficacy than the send out quantity of heat, can produce higher stack temperature. And we all the power of the internal electronic parts will as the rise of the temperature and shorten the service life. So the efficiency is to determine the power of life is the most fundamental factor, efficiency can't too low, otherwise the cost on the power supply of heat is too big. In more than 80% is ok, however, efficiency and lamp plate matching the relevant law.
10, 200W led Flood light power supply size Height is limited, the main factors are used for the size of the T6 tube/T8 height can't demanding than 9 mm. The height of the T10 tube more than 15 mm. Length can be slightly long, easier to heat dissipation.