The LED illuminating material is greatly influenced by the environment, such as the rising temperature will increase the current of the LED, and the increase of the voltage will influence the current of the LED, too. If the LED solar street light is always in the condition of over current, the service time of the LEDs will be decreased greatly. And the constant current can guarantee the working current does not influenced by the changing of the temperature or voltage.
The deviation of the constant current accuracy of the solar street lights on the market can be ±8%, which exceed the demands of ±3% greatly. And the light source should be trimmed to reach the requirements of ±3%.
The recommended working voltage of the LED is 3.0-3.5 V. according to the tests t hat the working voltage of most solar street lights is 3.2V, so it will be reasonable to calculate it with 3.2V. The total voltage of the N LEDs in series equals to 3.2*N.
The rated working current of the LED is 350mA, and some factories make it to 350mA. In practical, the solar street light may radiate more heat under this current. It will be ideal to design the working current to 320mA. It will be better to decrease the heat radiation and change more electrical energy into light energy.
In order to make the input voltage of the LED solar street light in the wide range of AC 85-265V, the series and parallel method of the LEDs on the lamp panel should be appropriate. Avoid to use the wide voltage, and try to classify them into AC 220V and AC 110V to guarantee the reliability of the current source.
The current source applied nowadays is the non-isolated voltage reductive constant-current power supply, and the required voltage is 110V, and the output voltage cannot be over 70V, and the serial numbers cannot exceed 23. If the input voltage is 220V, the output voltage can be 156V, which means that the serial number cannot be over 45. The parallel number cannot be too many, or the working current will be large.
It is difficult to put the isolate current source of 15W into the power supply tube of the LED solar street light, for the large volume of the transformer. So cost effective of the isolated type is not that good. And the volume of the non-isolated type can be small, and that minimum can be 8mm high. In practical, there is no safety problems if the safety measures are taken for the non-isolated type. If the space is enough, the isolate type is OK.
Some consumers will find it difficult if they search for the power source after the design of the lamp panel. For the large current and high voltage will cause serious heat radiation and low efficiency, and vice versa. In practical, the power source can work better to choose a perfect series-parallel method to make all the LEDs have the same voltage and current. It will be better to negotiate with the power source supplier or produce power source by itself.
In the rated voltage, the small working current and low heat radiation will prolong the service time of the solar street light, and vice versa. The LED beam is sensitive to the AC volume, and if the AC volume is high, the light comfort will be bad. Generally, the electrolytic capacitor is applied to maintain the voltage to decrease the AC volume of the output voltage. The choosing of the high voltage electrolytic capacitor for the non-isolated type is the same with the isolated type, and the capacitor of the output end should choose 1 UF<6 MA. The electrolytic capacitor of the dimming LED power source should meet 1U F<0.5 MA.
Input power minus the output power, which is quite important, and the number is big means low efficiency, which means that most of the input power is transformed into heat. And if it is fixed inside the light, the heat will increase the temperature inside the light. And all the electronic parts inside the power source will be decreased with the increasing of the temperature. So the efficiency is the fundamental factor to decide the service time of the power source, and the efficiency cannot be too low. The efficiency of the non-isolated type is higher than that of the isolated type, which is over 80%, and the efficiency is influenced by the connection method of the light panel.
The main factor should be taken into consideration in the heat radiation plan, and appropriate temperature can increase the service time of the solar street light, and the aluminum alloy is good for heat radiation. So the LEDs are attached to the aluminum basis to extend the area of heat radiation.
Hot Product
Copyright © 2011-2018 by NOKIN All Rights Reserved.
