However, DC control approach involves some problems to solve which are the thermal management of
components heating and its low energetic efficiency. On the other hand, we could improve LEDs
performances with the PWM control which uses a signal whose frequency varies between 100 and 1000
Hz to bring the LED in ON or OFF mode [1, 2]. This technique is very helpful for minimizing energy
consumption and lowering operating temperature of the device and it is under development by our
research group.
In this paper, we will present our study results based on DC current regulation of LEDs luminaries and
which can be directly applied to solar lighting systems [3, 4]. Our designed DC driver is using a
conventional electronic regulator LM317T having a TO-220 package (Figure 1-b) that has three (03) pins.
Its output voltage (VOUT) varies from 1.2V to 37V and has a maximum output current of 1.5A. For a well
functioning of the LM317 voltage regulator, the values of (VIN-VOUT) must stay in the interval from 1V to
3V [5]. If all of these conditions are respected then the LM317 regulator assures that (VOUT - VADJ) =
1.25V all the time. Then, in order to assure a regulation of current, we must insert a resistance (R1)
between the pin VOUT and VADJ. An optional capacitor can be connected between the output and ground to
give more stability to the regulator.
However, DC control approach involves some problems to solve which are the thermal management ofcomponents heating and its low energetic efficiency. On the other hand, we could improve LEDsperformances with the PWM control which uses a signal whose frequency varies between 100 and 1000Hz to bring the LED in ON or OFF mode [1, 2]. This technique is very helpful for minimizing energyconsumption and lowering operating temperature of the device and it is under development by ourresearch group.In this paper, we will present our study results based on DC current regulation of LEDs luminaries andwhich can be directly applied to solar lighting systems [3, 4]. Our designed DC driver is using aconventional electronic regulator LM317T having a TO-220 package (Figure 1-b) that has three (03) pins.Its output voltage (VOUT) varies from 1.2V to 37V and has a maximum output current of 1.5A. For a wellfunctioning of the LM317 voltage regulator, the values of (VIN-VOUT) must stay in the interval from 1V to3V [5]. If all of these conditions are respected then the LM317 regulator assures that (VOUT - VADJ) =1.25V all the time. Then, in order to assure a regulation of current, we must insert a resistance (R1)between the pin VOUT and VADJ. An optional capacitor can be connected between the output and ground togive more stability to the regulator.
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