Technical questions and answers about LED street lamp
The lighting engineering of LED lighting industry is not only influenced by the global environment, but also has its industry particularity. LED street lamp power supply is the most important part of the current led development. There are many schemes and unique design methods for the relevant design of LED technology. Let's have a look at them one by one.
1. Why should LED street lamp power supply be constant current?
The characteristics of LED lighting materials determine that they are greatly affected by the environment. For example, with the increase of temperature, the current of LED will increase; with the increase of voltage, the current of LED will also increase. Long term operation over rated current will greatly shorten the service life of LED lamp beads. The constant current of LED is to ensure that the working current value is constant when the environmental factors such as temperature and voltage change.
2. LED street lamp power supply constant current accuracy
The constant current accuracy of some power sources on the market is poor, with an error of ± 8%. The constant current error is too large. The general requirement is ± 3%. According to 3% design plan. The production power supply needs to be adjusted to achieve ± 3% error.
3. Working voltage of LED street lamp power supply
Generally, the recommended working voltage of LED is 3.0-3.5v. After testing, most of the LEDs work at 3.2V, so it is reasonable to calculate as 3.2V. Total voltage of N beads in series = 3.2 * n
4. What is the most appropriate working current of LED street lamp power supply
For example, the rated working current of LED is 350 Ma, which is used up in some factories at the very beginning. In fact, the working heat is very serious under this current. After many comparative tests, it is ideal to design it as 320 ma. Reduce the heat as much as possible, and make more electric energy into visible light energy.
5. How wide is the series parallel connection and wide voltage of LED street lamp power board?
In order to make the LED street lamp power supply work in a wide range of input voltage AC85-265V, the LED series parallel connection mode of the lamp board is very important. Try not to use wide voltage. It can be divided into AC220V and AC110V, so as to ensure the reliability of power supply. As the current power supply is generally non isolated step-down constant current power supply, when the required voltage is 110V, the output voltage shall not exceed 70V, and the number of series connection shall not exceed 23. When the input voltage is 220V, the output voltage can reach 156v. That is to say, the serial number shall not exceed 45. The number of parallel connection should not be too much, otherwise the working current is too large and the power supply is heated seriously. There is also a wide voltage scheme, APFC active power compensation is to use L6561 / 7527 to raise the voltage to 400V, and then reduce the voltage, equivalent to two switching power supplies. This plan is only used under certain conditions