Top 10 LED Street Lights Technical Features

OFweek Lighting Reuters LED lighting industry lighting lighting project, not only affected by the global environment, but also its industry-specific. The LED street lamp power supply is precisely the most important thing in the development of LED. For the related design of LED technology, there are already many kinds of schemes and unique design methods. Let’s get to know one by one and tell you secretly.

1. Why does a LED street lamp power supply must have a constant current?

The characteristics of LED lighting materials determine that they are affected by the environment. For example, if the temperature changes, the LED current will increase, the voltage will increase, and the LED current will increase. Long-term operation beyond the rated current will greatly shorten the LED lamp life. The constant current of the LED is to ensure that the operating current value does not change when the environmental factors such as temperature and voltage change.

2, LED street lamp power supply constant current accuracy accuracy of some of the power supply on the market is poor, like the market's popular recommended solutions such as constant current program, the error reached ± 8%, constant current error is too large. The general requirement is ±3%. Press 3% of the design plan. The power supply must be fine-tuned to achieve ±3% error.

3. The working voltage of the LED street lamp power supply The recommended working voltage of the LED is 3.0-3.5V. After testing, most of the work is at 3.2V, so the 3.2V calculation formula is reasonable. Total voltage of N beads in series = 3.2* N

4, LED lamp power supply operating current is what is the most appropriate, such as LED rated operating current 350 mA, some factories use it to start, design 350 mA, in fact, the current work under the current heat is very serious, After several comparison tests, designing 320 mA is ideal. Minimize the amount of heat and allow more electricity to become visible light.

5, LED street light power board series and parallel and wide voltage to how wide?

To make the LED street light power work in a wide range of input voltage AC85-265V, the LED series parallel connection of the lamp panel is very important. Try not to use a wide voltage, which can be divided into AC220V, AC110V classification as possible, so as to ensure the reliability of the power supply. Since the current power supply is generally a non-isolated buck constant current power supply, the output voltage should not exceed 70V when the required voltage is 110V, and the number of series connections should not exceed 23 strings. When the input voltage is 220V, the output voltage can reach 156V. That is, the number of concatenations does not exceed 45 strings. Do not add too many parallel connections. Otherwise, the operating current will be too high and the power supply will become extremely hot. There is also a wide voltage scheme, APFC active power compensation is to use L6561/7527 to raise the voltage to 400V, and then step down, the equivalent of two Switching Power Supply. This program is only used under certain conditions.

6, isolation / non-isolated General isolated power supply such as made of 15W, placed in the LED street lamp power supply tube, the transformer is very large, it is difficult to put in. Mainly depends on the spatial structure depending on the specific circumstances, the isolation can only be done generally 15W, rarely more than 15W, and the price is very expensive. Therefore, the cost-effectiveness of isolation is not high. Generally, it is non-isolated and occupies more mainstream. The volume can be made smaller. The minimum can be up to 8 mm. In fact, non-isolated security measures are done well, and there is no problem. Space allows it to do isolated power.

7. How can LED street lamp power supply match the lamp bead board?

Some customers first designed the lamp board, looked for the power supply, and found that it was difficult to have a suitable power supply, either the current was too high, the voltage was too low (such as 7X1WI>350mA, or V<20V); or the current was too low, and the voltage was too high (such as I<200mA or V>25V) results in severe heat generation, low efficiency, or insufficient input voltage range. In fact, choosing the best series and parallel connection method, the voltage and current applied to each LED is the same, and the power supply's effect can exert the best performance. The best way is to first communicate with the power supply manufacturers, tailor-made. Or own production power.

8. Series parallel connection of LED and PFC power factor Isolated input AC220V high-pressure end electrolytic capacitor capacity generally input power 1W = 1UF, AC110V1W = 2UF There are three kinds of power supply PFC on the market: One is without PFC no power factor compensation For a dedicated circuit, the PF value is generally around 0.65; the two are passive power factor compensation PFC circuits, that is, passive power factor compensation lamps, also called flow-through circuit boards are currently the most widely used reliability, PF The value is generally about 0.92; also use three kinds of active active 7527/6561 circuit to do, that is, active power factor compensation, called APFC circuit AC220V, AC110V can use the same capacity of electrolytic capacitors, use 1W = 1.5UF. The PF value can reach 0.99, but the cost of this solution is slightly less expensive than the second solution. So the second program is used more often. For a passive PFC circuit, also known as a valley-filled PFC circuit, its DC operating voltage range is half of the AC input voltage peak. If the input is 220V, its peak value is 220*1.414=312V, and half of the peak voltage is 156V. On the non-isolated basis, the output wave is no lower half of the upper half wave.

Therefore, it is advisable that the number of LED street lamp power beads be up to 45 strings in series. Therefore, in order to obtain a relatively large power factor, the number of concatenations of the lamp beads should not be too small. Otherwise, the optimal working state cannot be achieved. The number of series connections on the isolated power supply is related to the number of turns of the secondary winding and must be achieved. The power supply must meet the output power. The smaller the working current of the electronic component in the rated voltage working range is, the longer the life is at the end of heating and the shorter the service life is. The LED street lamp power beads are very sensitive to the AC parts, and the higher the AC part weight, the worse the light comfort. Generally use electrolytic capacitors to maintain the voltage, as much as possible to reduce the output voltage AC parts, the bottom electrolytic capacitor capacity can not be too small, the ratio of capacity and output current is 1UF <1.5MA or LED will flash. Non-isolated input high-voltage electrolytic capacitor selection and isolation, the output capacitor selection 1UF <6MA. Dimming LED power supply in the output electrolytic capacitor to meet 1UF <0.5MA.

9, LED street lamp power supply power input power minus output power value, this parameter is particularly important, the greater the value the lower the efficiency, it means that a large part of the input power is converted into heat; if it is installed in the lamp This produces a very high temperature, plus the heat generated by one of our LED's is more superimposed to generate higher temperatures. The lifetime of all the electronic components inside our power supply will be shortened as the temperature increases. Efficiency is the most fundamental factor in determining the life of a power supply. The efficiency cannot be too low, otherwise the heat consumed on the power supply is too high. Non-isolated efficiency is higher than the isolated type, generally more than 80% can be, but the efficiency and the lamp board matching connection 10, LED street lamp power cooling solution is the main factor LED street lamp power beads in the use of under the heat conditions Can greatly extend the life, generally use aluminum alloy, easier to heat. That is, the LED street lamp power bead is attached to the aluminum substrate, and the external heat dissipation area is maximized.

The face of such a vast LED market is indeed full of vitality, the main scientific development, can achieve a leading position in a number of technical areas, I believe that China's LED companies will become more powerful.