Research And Design Of LED Driver For Street Lighting

With the global energy crisis and environmental problems exacerbated, theconcept of energy saving and emission reduction has been firmly established. Themeaning of developing efficient and environmental green lighting products isself-evident. As the technology on LED become more and more robust, LEDlighting technology has become the most promising lighting system, especially inroad lighting system. The LED driver is an important guarantee for thedevelopment of LED product. In the process of promoting LED lighting, however,there are some problems: the power factor problem, driving mode, arrangement ofLEDs, the fault diagnosis and control strategies. Based on this problem this essaymakes a study of some problems in LED driver technology. Then design a120Wdigital LED SMPS.The topologica of LED SMPS contains two power structure: power factorcorrection and DC-DC converter. First, the paper analyzes the principle of powerfactor correction techniques, makes a detailed analysis of the critical conductionmode of Boost circuit.Then complete the calculation of circuit parameters and thedesign of the controller based on MC33262. Secondly, the paper analyzes the LCresonant converter, then establishes the model of LED load. On this basis, thispaper use fundamental method to analysis the circuit and discusse theimplementation of the soft-switching conditions. Also, complete the calculation ofthe passive parameters and the design of controller. To the open-circuit fault ofLEDs, we propose a open-circuit auto-detection circuit. The output current of thedriver can be adjusted according to the number of the strings in the open-circuitstate. Then the current of a single LED ring can keep a constant value even whenthe number of working LED strings is changed.The input voltage is85Vac~265Vac. The output voltage is47V-50V andouput current is a constant current of2.64A when in full load. The experimentalresults verify the control method proposed in the paper. The design of theprototype has a good dynamic performance and stability.