Top 10 Knowledge Points of Led Street Lights
October 17, 2022
The lighting project of LED lighting professional light is not only affected by the global environment, but also has its own specificity. And Led Street Light power supply is the top priority of LED development. Regarding the related planning of LED technology, there are already a variety of plans and common planning methods. Let's take a look at them one by one. 1. Why must the LED street light power supply be constant current?
The characteristics of LED lighting materials determine that it is greatly affected by the environment. For example, if the temperature changes, the current of the LED will increase, and the voltage of the LED will increase. Excessive current operation for a long time will greatly shorten the service life of LED lamp beads. The LED constant current is to ensure that its operating current value remains unchanged when environmental factors such as temperature and voltage change. 2. LED street lamp power constant current accuracy
The constant current accuracy of some power supplies in the market is poor. For constant current plans such as the popular recommendation plan on the market, the error reaches ±8%, and the constant current error is too large. The general requirement is ±3%. According to the 3% planning plan. The production power supply needs to be fine-tuned to achieve ±3% error. 3. Operating voltage of LED street light power supply
The recommended operating voltage of the general LED is 3.0-3.5V. After testing, most of the operations are performed at 3.2V, so the calculation formula of 3.2V is more reasonable. The total voltage of N lamp beads in series = 3.2*N 4. What is the most suitable operating current of the LED street light power supply?
For example, the additional operating current of LED is 350 mA. Some lighting design factories use up 350 mA at the beginning. In fact, the operation heat is very serious under this current. After many comparison experiments, it is more ideal to design 320 mA. of. Minimize heat generation and allow more electrical energy to become visible light energy. 5. How wide should the series-parallel and wide voltage of the LED street light power board be?
In order to make the LED street light power supply work in the range of AC85-265V with a relatively wide input voltage range, the series-parallel method of the LEDs of the light board is very important. Try not to use wide voltage, can divide AC220V, AC110V as much as possible, so as to ensure the reliability of the power supply. Because the current power supply is generally a non-blocking step-down constant current power supply, when the required voltage is 110V, the output voltage should not exceed 70V, and the number of series connections should not exceed 23 series. When the input voltage is 220V, the output voltage can reach 156V. That is to say, the number of concatenations does not exceed 45 strings. The number of parallel connections should not be too many, otherwise the operating current will be too large, and the power supply will heat up severely. There is also a wide voltage plan, APFC active power compensation is to first use L6561/7527 to raise the voltage to 400V, and then step down, which is equivalent to two switching power supplies. This plan is only used under certain conditions. 6. Barrier/non-barrier
Generally, the blocking power supply is made into 15W and placed in the power tube of the LED street light. The transformer is very large and difficult to put in. It mainly depends on the spatial structure and depends on the specific situation. Generally, the barrier can only achieve 15W, and there are very few exceeding 15W, and the price is very expensive. Therefore, the cost-effectiveness of the barrier is not high. Generally, the right and wrong barriers account for more mainstream, and the volume can be made smaller, and the minimum height can be 8 mm. In fact, there is no problem with non-blocking safety measures. . Space permits can also be used to block the power supply. 7. How can the LED street lamp power supply be matched with the lamp bead board?
Some customers plan the light board first, then find the power supply, and find that it is difficult to have a suitable power supply, either the current is too large and the voltage is too small (such as 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 severe heat generation, low power, or poor input voltage range. In fact, choose an optimal series-parallel connection method, the voltage and current applied to each LED are the same, and the power supply can play the best function. The best way is to first communicate with the power supply manufacturer and customize it. Or produce your own power supply. 8. LED series and parallel connection and PFC power factor
Barrier input AC220V high-voltage side electrolytic capacitor capacity is generally based on input power 1W=1UF, AC110V1W=2UF There are three types of power supply PFC in the market: One is without PFC and no power factor compensation special circuit, and its PF value is generally around 0.65; The second type is the passive power factor compensation PFC circuit, that is, the passive power factor compensation lamp, also known as the flow-by-current circuit board, which is the most widely used and has the best reliability, and the PF value is generally around 0.92; There are also three types of lighting projects using active automatic 7527/6561 circuits, that is, active power factor compensation, which is called AC220V in APFC circuits, and AC110V can use electrolytic capacitors of the same capacity, 1W=1.5UF. The PF value can reach 0.99, but the cost of this plan is twice as expensive as that of the second plan, and the reliability is slightly worse. So the second plan is used more. About passive PFC circuit: also known as valley-filling PFC circuit, its DC operating voltage range is half of the peak value of the AC input voltage. If the input is 220V, the peak value is 220*1.414=312V, half of the peak voltage is 156V, and the output wave is the upper half wave without the lower half wave on the basis of non-blocking. Therefore, the maximum number of LED street lamp power beads in series is less than 45 strings. Therefore, in order to obtain a relatively large power factor, the number of series connection of lamp beads should not be too small, otherwise the optimal working condition will not be achieved. The power supply power should be satisfied with the output power. The smaller the operating current of electronic components within the operating range of extra voltage, the longer the heat generation and the longer the life, otherwise the life will be shorter. LED street light power beads are very sensitive to the amount of communication, and the higher the amount of communication, the worse the light comfort. Generally, electrolytic capacitors are used to maintain the voltage, and the voltage communication weight of the output terminal should be reduced as much as possible. The capacity of the electrolytic capacitor at the bottom voltage terminal should not be too small, and the capacity and output current share should be 1UF<1.5MA, otherwise the LED will flash. The selection of high-voltage electrolytic capacitors at the input end of the non-blocking type is the same as that of the blocking type, and the selection of the capacitor at the output end is 1UF<6MA. The electrolytic capacitor at the output end of the dimming LED power supply should satisfy 1UF<0.5MA.
9. LED street light power supply power
Input power minus output power value, this parameter is particularly important, the larger the value, the lower the power, which means that a large part of the input power is converted into heat and emitted; if it is installed in the lamp, a very high temperature will occur , coupled with the heat emitted by a luminous efficiency ratio of our LED, a higher temperature will be superimposed. And the life of all electronic parts inside our power supply will be shortened as the temperature rises, so the power determines the life of the power supply. The most basic factor is that the power cannot be too low, otherwise the heat consumed on the power supply will be too large. The power of the non-blocking type is higher than that of the blocking type, generally more than 80%. However, the power is related to the matching connection method of the lamp board. 10. LED street light power dissipation
The main element of the heat dissipation plan is that the use of LED street lamp power beads can greatly extend the life under the condition of not overheating. Generally, aluminum alloy is used, which is easier to dissipate heat. That is, the LED street lamp power supply beads are attached to the aluminum substrate, and the external heat dissipation area is expanded as much as possible. Faced with such a broad LED market, it is really full of vitality, mainly through scientific development, and can gain a leading position in certain technical fields. I believe that my country's LED enterprises will become stronger and stronger. The above content is provided by WOSEN. WOSEN is a professional manufacturer and supplier of Led Flood Light, Led Street Light, Led Solar Light, etc. For more information, please visit https://www.wosenled.com/ or contact admin@wosenled.com or WhatsApp +86-13425434349
