Ten main points of LED street lamp power design: Yangzhou Chuang Chuang photoelectric Group Co., Ltd.

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Ten main points of LED street lamp power design

2020/4/29 11:15:56 Click:
  
Throughout the 2011, under the shadow of the financial crisis, with the European debt crisis, the United States and other multinational credit rating was downgraded and the emerging market Guo Jia inflation intensified, the international environment is facing new uncertainties and complexity. At the same time, the state puts the price control in the first place in the economic work. Under this request, a series of measures such as raising the rate of deposit reserve, raising interest rates, limiting the purchase of housing, and appreciating the renminbi are coming. Many small and medium-sized enterprises are facing the pressure of capital, market shrinkage and product De stocking. As a new industry, the lighting industry of LED lighting industry is affected by the global environment as well as the particularity of its industry.
  
and LED street lamp The power supply is the most important part of the development of LED at present. For the related design of LED technology, there are many schemes and unique design techniques.
  
1, why does LED street lamp power supply must have constant current?
  
The characteristics of LED lighting materials determine that they are greatly influenced by the environment. For example, the temperature changes will increase, the current of LED will increase, the voltage will increase, and the current of LED will also increase. Long term operation over rated current will greatly shorten the service life of LED lamp beads. The LED constant current is to ensure that its current value remains unchanged when the environment factors such as temperature and voltage change.
  
2. LED street lamp Constant current accuracy of power supply
  
In the market, the constant current accuracy of some power supply is poor, such as the constant current recommendation scheme that is popular on the market. The error is up to + 8%, and the constant current error is too large. The general requirement is at + 3%. Press 3% design. The production power should be fine tuned to achieve an error of + 3%.
  
3. Working voltage of LED street lamp power supply
  
The recommended voltage for general LED is 3.0-3.5V. After testing, most of the work is in 3.2V, so the 3.2V formula is more reasonable. The total voltage of N beads connected in series is =3.2* N
  
4. How much is the working current of LED street lamp power supply?
  
For example, the rated working current of LED is 350 Ma, some factories are used at the very beginning, and the design is 350 ma. In fact, the heat generated by the current is very serious. It is ideal to design 320 Ma after many tests. Minimize the heat and make more electric energy visible light.
  
5. How wide is the series parallel connection and the wide voltage of the LED street lamp power board?
  
To make the power of LED street lamp work in a wide range of input voltage AC85-265V, the LED serial and parallel mode of the lamp board is very important. Try not to use a wide voltage, can be divided into AC220V, AC110V classification as far as possible, so as to ensure the reliability of power supply. Since the current power supply is generally a non isolated buck type constant current power supply, when the voltage is 110V, the output voltage should not exceed 70V, and the series number should not exceed 23 strings. When the input voltage is 220V, the output voltage can reach 156V. That is to say, there are no more than 45 strings in series. The number of paralleling is not too much, otherwise the working current is too large and the power supply is very serious. There is also a wide voltage scheme. The APFC active power compensation is to raise the voltage to 400V by L6561/7527 and then to lower the voltage, which is equivalent to two switching power supplies. This scheme is used only under certain conditions.
  
6, isolated / non isolated general isolated power supply, such as 15W, is placed in the LED street lamp power supply. The transformer is very large and difficult to put in. Mainly depends on the spatial structure depending on the specific circumstances, isolation can only be 15W, less than 15W, and the price is very expensive. Therefore, the cost performance of isolation is not high. Generally, non isolation is the mainstream, and the volume can be smaller. * small can achieve a height of 8 millimeters. In fact, there is no problem with the safety measures that are not isolated. Space can also be used as an isolated power source.
  
7, how can LED street lamp power supply match with the bead board?
  
Some customers first design the lamp board, then look for the power supply, and find it difficult to have the right power supply, or the current is too large, the voltage is too small (for example, 7X1WI > 350mA or V < 20V), or the current is too small and the voltage is too high (such as I < 200mA or V > 25V). The result is serious fever, low efficiency, or insufficient input voltage range. In fact, the selection of an excellent serial connection mode is the same as the voltage and current on each LED, but the effect of the power supply can achieve good performance. The best way is to communicate with power suppliers and tailor them. Or self produced power.
  
8, LED series parallel and PFC power factor.
  
Isolated input AC220V high voltage end electrolytic capacitor capacity in general input power 1W=1UF, AC110V1W=2UF current market power PFC has three situations: one is no PFC without power factor compensation special circuit, its PF value is generally around 0.65; the two is passive power factor compensation PFC circuit, that is, passive power factor compensation lamp, also known as the current circuit board is currently made. * * wide reliability * good, PF value is generally around 0.92; also used three kinds of active active 7527/6561 circuit, that is, active power factor compensation, known as APFC circuit AC220V, AC110V can use the same capacity of electrolytic capacitors, choose 1W=1.5UF. The PF value can reach 0.99, but the cost of this solution is twice as expensive as that of the second solutions. So the second schemes are used more. For passive PFC circuits, also known as valley filling PFC circuits, the DC operating voltage range is half of the peak value of AC input voltage. If the input is 220V, the peak value is 220*1.414=312V, half of the peak voltage is 156V. On the non isolated basis, the output wave is the upper half wave without the second half wave.
  
Therefore, LED street lamp power supply beads series number is more than 45 strings below is appropriate. Therefore, in order to get a relatively large power factor, the number of bulbs can not be too small, otherwise it will not be able to work well. The number of series connected to the isolated power supply is related to the number of turns of the secondary winding. The power supply must meet the output power. In the range of rated voltage, the smaller the working current, the longer the life and the longer the life. LED street lamp power beads are very sensitive to the amount of communication. The higher the amount of communication, the poorer the light comfort. Generally, it is necessary to maintain the voltage with electrolytic capacitors, minimize the AC voltage of the output terminals, and the capacity of the bottom voltage terminals can not be too small. The ratio of the capacity to the output current is 1UF < 1.5MA, otherwise the LED will appear flicker. The high voltage electrolytic capacitors of the non isolated input terminals are the same as those of the isolated ones, and the output capacitance is 1UF < 6MA. The electrolytic capacitor of the dimming LED power supply at the output terminal should meet 1UF < 0.5MA.
  
9. LED street lamp Power supply efficiency
  
The input power minus the output power, this parameter is particularly important, the greater the value, the lower the efficiency, which means that a large part of the input power is converted to heat emission. If it is installed in the lamp, it will generate a very high temperature, coupled with the luminous efficiency of our LED. It will superimpose a higher temperature. The life of all electronic components in our power supply will shorten with the increase of temperature. So efficiency is the fundamental factor determining the life of the power supply. The efficiency can not be too low, otherwise the heat consumed on the power supply is too large. The non isolation efficiency is higher than the isolation type. Generally, it is more than 80%. However, the efficiency and the matching method of the lamp board are related to 10 and LED street lamp power dissipation.
  
The main reason of the heat dissipation plan is that the power supply beads of LED street lamps can extend life greatly under the condition of no overheating. That is, the LED street lamp power beads are attached to the aluminum substrate, and the external area is maximally expanded.
  
Facing such a vast LED market is really full of vitality, mainly scientific development, a number of technical areas can be a superior position, I believe our LED enterprises will become more powerful.
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