Circuit Design-high-power tunnel lighting LED light source

The forward voltammetry characteristics of LED and ordinary diodes are similar, plus a slight change in the forward voltage, the forward current will have a great change, resulting in a rapid rise in LED internal loss and heating, seriously affecting the normal operation and life of LED. In order to prevent this from happening, high-power leds generally must be powered by constant current. In order to improve the efficiency of the current source as much as possible and reduce heating, the input voltage of the current source must be reasonably controlled, so that its maximum value is the same as the current after deducting the internal voltage drop, and also matches the total voltage required by the LED. The internal loss is small, the reliability of the current source can be guaranteed.

Tunnel lighting generally requires a large number of lamps, power consumption is huge, in order to save energy and reduce the “pollution” of the power grid, the driver of LED tunnel lights also requires its power factor and harmonic generation must meet the relevant standard requirements, and give due consideration to electromagnetic interference and electromagnetic compatibility.

(1) The use of high conversion efficiency, high stability of the power supply, the conversion efficiency is greater than 87%, the power factor is greater than 95%, and the switching power supply (96~264V) with strong resistance to external power grid voltage fluctuations, is equipped with constant current circuit design, and the LED light source is driven by constant current to ensure the service life of the LED.

(2) The control circuit suitable for tunnel lighting is used to adjust the power of the lamps according to different lighting segments and different time periods of the tunnel, so as to achieve good lighting effects and energy saving purposes. The introduction section, adaptation section, transition section and exit section of the tunnel inlet section are driven by different currents to make them as close as possible to the requirements of the tunnel lighting curve and achieve the best lighting effect. The tunnel inlet and outlet section adopts a timing adjustment function, adjusts the output current through PWM dimming or uses dual power supply, and at night it is powered by a single power supply, so that its power is reduced to 50% of the daytime lighting, both in the day and night, effectively reducing the “bright hole” and “black hole” phenomenon

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