This paper mainly due to the presence of existing LED street light drive circuit electrolytic capacitors and shorten its life shortcomings , we propose a non-electrolytic capacitor LED driver circuit design. The program to extend the life of the circuit as the theme to switching power supply combined with a linear basis , exceed the full use of their respective advantages, because the switching power supply with high efficiency of energy conversion characteristics of the linear power supply has no output ripple characteristics, the designs take advantage of their respective strengths to replace electrolytic capacitor filter , effective solution to the existing LED drive circuit of short service life . The LED driver circuit without a large -capacity electrolytic capacitor , a small capacitor can be used for film capacitors, long-life capacitive elements , it has a long life , high efficiency, small ripple current characteristics, and has high safety and stability .
LED (light emitting diode ) is a new generation of green lighting , energy saving, environmental protection, high brightness, long life and other advantages . Not only is it the new darling of lighting , but also with much related to people's lives . Therefore , the development of long-life drive power, build high- efficiency, low cost , high power factor and is the LED light quality and overall performance is the key , but also the needs of the development of LED lighting technology . According to incomplete statistics, the existing incandescent bulb life LED lights less than about 40 times . Because not only the light emitting diode direct current driven device , but also media converter, a photoelectric conversion function. Its main function is the current flowing through the electrical energy into light energy , so its advantage is energy-saving light source than the general efficiency and working life to be higher . However, the LED drive power rectifier and filter circuit generally requires the use of large-capacity electrolytic capacitor. Electrolytic capacitor life is generally l05 ℃ / 2000h, that is when the capacitor rises to 105 ℃ ambient temperature when its life is only 84 days , even when operating at a temperature of 85 ℃ environment, the service life of only 332 days , so the electrolytic LED driver circuit capacitor life is impeding the main reason . In order to improve drive power of life , it is necessary to remove the electrolytic capacitor , as this paper , we propose a non-electrolytic capacitors , high-brightness LED driver power supply.
Circuit topology using flyback topology circuit , a PWM switching frequency is controlled so that the output constant current and voltage drive LED street light. Including: former level protection circuit , EMI filter circuit , the rectifier circuit , RCD clamp circuit , synchronous rectification circuit, a power conversion circuit , the output filter circuit, the feedback circuit, control circuit.
To make the circuit less subject to electromagnetic interference , EMI filter circuit is connected to the first level protection circuit, the circuit through which the higher harmonic filter and the circuit of the surge .
Part of the input rectifier , respectively, by the bridge rectifier circuit and the π -type filter circuit , because the diode with a single conduction characteristics , so the bridge rectifier circuit converts AC power to DC unidirectional , and then in the π -type filter circuit under the effect of stable output DC voltage.
Then by the control circuit adjusts and controls the output reaches the design value , and finally through the output filter circuit reduces the output ripple current into direct current , and finally use the DC output to the LED .
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