Ten technical characteristics of LED street light
LED lighting industry lighting engineering, both affected by the global environment, but also its industry-specific. The LED street lamp power supply is precisely the most important development of the LED, LED technology for the relevant design, there are already a variety of programs and unique design techniques, we come to understand one by one, secretly tell you.
1, LED street lamp power supply why must constant current?
The characteristics of LED lighting materials determine its environmental impact, such as temperature changes, LED current will increase, the voltage increases, LED current will increase. Long-term over rated current work, will greatly shorten the LED lamp life. The LED constant current is the temperature and voltage changes in environmental factors, to ensure that the current value of its work.
2, LED street lamp power supply constant current accuracy
Some of the market power supply constant current accuracy is poor, such as the recommended program on the market constant current program, the error of ± 8%, constant current error is too large. The general requirements of ± 3% on it. By 3% design. Production power to be fine-tuning in order to achieve ± 3% error.
3, LED street lamp voltage
General LED's recommended operating voltage is 3.0-3.5V, tested, most of the work at 3.2V, so calculated by 3.2V more reasonable. N total number of lamp beads in series = 3.2 * N.
4, The most appropriate current for LED street lamps
For example, LED rated current of 350 mA, some factories started to use, design 350 mA, in fact, this current working fever is very serious, after many comparative tests, designed 320 mA is ideal . Minimize the heat, let more electricity into visible light energy.
5, LED street lamp power strip series and wide voltage to be wider?
LED street lamp power supply to work in the input voltage range of a wide range of AC85-265V, LED light board series and parallel connection is very important. Try not to use a wide voltage, can be divided into AC220V, AC110V as much as possible in order to ensure the reliability of the power supply. Due to the current power supply is generally non-isolated step-down constant current power supply, the required voltage of 110V, the output voltage should not exceed 70V, the number of series does not exceed 23 strings. When the input voltage is 220V, the output voltage can reach 156V. In other words, the number of series does not exceed 45 strings. Not too much parallel number, or operating current is too large, the power supply heat is serious. There is also a wide voltage program, APFC active power compensation is the first to use L6561 / 7527 voltage up to 400V, and then buck, equivalent to two switching power supply. This program is only used under certain conditions.
6, isolated / non-isolated
General isolation of power, such as made of 15W, placed on the LED lamp power tube, the transformer is large, it is difficult to put in. The main space structure depends on the specific circumstances, the general isolation can only do 15W, less than 15W, and the price is expensive. Therefore, the isolation of the cost is not high, the general non-isolated more mainstream, the volume can be made smaller, the minimum can do high 8 mm, in fact, non-isolated safety measures well, there is no problem. Space allows isolation power can also be done.
7, LED street lamp power supply how to do with the lamp bead plate match?
Some customers design a good light board, find the power and find it difficult to have a suitable power supply, or the current is too large, the voltage is too small (such as 7X1WI> 350mA, or V <20v); or current is too small, the voltage is too high i <200ma or v> 25V), the result is serious fever, low efficiency, or the input voltage range is not enough. In fact, choose a best string and then connected to the voltage and current added to each LED is the same, but the power of the results can play the best performance. The best way is to communicate with the power supply manufacturers, tailor-made. Or own production of power.
8, LED series and parallel PFC power factor
Isolated AC220V high-voltage electrolytic capacitor capacity is generally the input power 1W = 1UF, AC110V1W = 2UF power PFC currently on the market there are three cases: one is without PFC power factor compensation circuit, the PF value is generally 0.65 ; Two kinds of passive power factor compensation PFC circuit, that is, passive power factor compensation lamp, also known as by-flow circuit board is currently the most widely used reliability, PF value is generally around 0.92; also used three Is active active 7527/6561 circuit to do, that is, active power factor compensation, known as APFC circuit AC220V, AC110V electrolytic capacitors can use the same capacity, choose 1W = 1.5UF. PF value can reach 0.99, but the cost of this program is more than double the reliability of the second solution slightly worse. So the second option is more. For passive PFC circuits: also known as valley-fill PFC circuits, the DC operating voltage range is half the peak 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 basis of non-isolated output wave for the first half of the wave without the second half wave.
Therefore, the maximum number of LED street lamp power beads 45 series is appropriate. Therefore, in order to get a relatively large power factor, the number of lamp beads in series can‘t be too small, otherwise not up to the best working condition, the number of isolated series power supply on the number of windings and the number of secondary windings must be done Power supply to meet the output power. Electronic components in the rated voltage range of work current is smaller the more heat the end of life, the longer the life expectancy will be shorter. LED street lamp power beads are very sensitive to the exchange of shares, the higher the share of light, the more comfortable the light. Generally use electrolytic capacitors to maintain the voltage, as much as possible to reduce the output voltage AC share, electrolytic capacitors at the end of the capacitor capacity can’t be too small, the capacity and output current ratio of 1UF <1.5ma otherwise led will appear flashing. Non-isolated high-voltage electrolytic capacitors at the input selection and isolation of the same type, the output capacitor selection 1uf <6ma. Dimmable led power supply electrolytic capacitors at the output to meet 1uf <0.5ma.
9, LED street lamp efficiency
Input power minus the output power value, this parameter is particularly important, the higher the value the lower the efficiency, it means that a large part of the input power into heat emitted; if it is installed in the lamp will have a high temperature, Plus one of our LED's luminous efficiency than the heat, it will generate a superposition of higher temperatures. And the life of all the electronic components inside our power supply will be shortened as the temperature rises. Therefore, efficiency is the most fundamental factor that determines the power life, efficiency can’t be too low, otherwise consume too much heat on the power supply. Non-isolated efficiency is higher than isolated, generally more than 80% can be, but the efficiency and light board matching connection
10, LED street lamp power supply heat
Cooling solution is the main factor LED street lamp beads in the use of power conditions can greatly extend the life expectancy, the general use of aluminum, more easy to heat. That is, LED lamp power beads attached to the aluminum substrate, the external try to expand the cooling area.
To face of such a vast LED market is full of vitality, the main scientific development, a few technical fields to obtain a leading position, I believe that China's LED business will be more and more powerful.