LED power several small secrets
LED lighting industry lighting engineering, both by the global environment, but also has its industry specificity. LED street lamp power is precisely the current development of the most important LED, LED technology for the relevant design, there are a variety of programs and unique design practices, we come to one by one to understand.
1, LED street lamp power supply Why must constant current?
LED lighting characteristics of the material determines its impact by the environment, such as the temperature rise, LED current will increase, the voltage increases, LED current will increase.
Long-term work than the rated current, will greatly shorten the LED lamp beads life. The LED constant current is the temperature and voltage and other environmental factors change, to ensure that its current value of the same.
2, LED street lamp power supply constant current accuracy
On the market some of the power of constant current accuracy is poor, as popular in the market recommended programs such as constant current program, the error of ± 8%, constant current error is too large.
General requirements in ± 3% on it. According to 3% of the design. The production of power to be fine-tuned to achieve ± 3% error.
3, LED street lamp power supply voltage
General LED recommended operating voltage is 3.0-3.5V, the test, most of the work in the 3.2V, 3.2V calculated by the formula is reasonable. The total voltage of N lamp beads in series = 3.2 * N
4, LED street lamp power supply power supply current how much is the most appropriate?
Such as LED rated current 350 mA, and some factories used to start to do, the design 350 mA, in fact, this current is very serious fever, the repeated comparison test, the design is 320 mA is ideal . To minimize heat, so that more energy into visible light energy.
5, LED street lamp power supply board series and parallel and wide voltage to more wide?
LED street lamp power supply to work in the input voltage range of a wide range AC85-265V, the light board of the LED string and parallel mode is very important. Try not to use a wide voltage, can be divided into AC220V, AC110V classification as much as possible, so as to ensure power supply reliability.
As the current power supply is generally non-isolated step-down constant current power supply, the required voltage 110V, the output voltage should not exceed 70V, the series number does not exceed 23 strings. When the input voltage is 220V, the output voltage can reach 156V. That is, the concatenation number does not exceed 45 strings.
Parallel number not too much, otherwise the working current is too large, the power fever serious.
6, Isolated / non-isolated
Isolated power supply, such as general made 15W, on the LED lights power tube, the transformer volume is very large, very difficult to put in. Mainly depends on the specific structure of the space, the isolation can only be done in general 15W, more than 15W very little, and the price is very expensive.
Therefore, the cost of isolation is not high, generally non-isolated more mainstream, the volume can be done smaller, the minimum can be high 8 mm, in fact, non-isolated security measures well, there is no problem. Space can also be done to do isolated power supply.
7, LED street lamp power supply how can we do with the lamp beads board match?
Some customers first design a good light board, and then find the power and found it difficult to have the right power, or the current is too large, the voltage is too small (such as 7X1WI> 350mA, or V <20V);
Either the current is too small and the voltage is too high (eg I <200mA or V> 25V), resulting in severe heating, low efficiency, or insufficient input voltage range.
In fact, choose one of the best string and parallel connection, plus the voltage and current on each LED is the same, while the power supply effect is able to play the best performance. The best way is to communicate with the power supply manufacturers, tailored. Or self-produced power.
8, LED series-parallel and PFC power factor
Electronic components in the rated voltage range of work the smaller the working current heating the more the longer the end of life, otherwise life will be shorter. LED street lamp power beads are very sensitive to the exchange of weight, the higher the amount of exchange of light the more comfortable the worse.
Generally use the electrolytic capacitor to maintain the voltage, usually choose long-life electrolytic capacitors, the output voltage AC as much as possible to reduce the weight of the end of the electrolytic capacitor capacity can not be too small, the capacity and output current ratio of 1UF <1.5MA LED otherwise Flashes.
Non-isolated input high-voltage electrolytic capacitor selection and isolation of the same, the output capacitor select 1UF <6MA. Dimming LED power supply in the output electrolytic capacitor to meet 1UF <0.5MA.
9, LED street lamp power supply efficiency
Input power minus the 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 into heat emitted; if it is installed in the lamp will produce a very high temperature , Coupled with our LED a light effect than the distribution of heat, it will stack produce a higher temperature.
And our internal power supply all electronic parts life will be shortened with the temperature rise.So that efficiency is to determine the most fundamental factor in power supply life, efficiency can not be too low, otherwise the heat consumed in the power supply is too large.
Non-isolated efficiency is higher than isolation, generally more than 80% can be, but the efficiency and light board matching connection.
10, LED street lamp power cooling
Cooling program is the main factor in LED street lamp beads in the heat, but under conditions of use can greatly extend the life of the general use of aluminum, more easy to heat. That is, LED lights power beads attached to the aluminum plate, the external cooling area as much as possible.
Faced with such a vast LED market is full of vitality, the main scientific development, a few technical areas can achieve a leading position, I believe that China's LED business will become more powerful.