The Research Of High Power LED Street Light Power Supply Based On LLC Resonance

Street lights are the public infrastructures of city civilization. Recent years, LED street lights stand out beyond many traditional ways of street lighting, and be promoted more and more widely. However, according to the volt-ampere characteristic of LED, it needs a special power supply equipment to convert the mains supply into stable DC power to drive LED glowing stably, instead of being powered by the mains power supply directly. The life and efficiency of the drive power supply become the bottleneck of restricting the LED street lights comprehensive promotion. A highly efficiency and stable LED street light driver power supply is needed to fundamentally solve the problem.A two-state distributed power system structure was used to the LED street light driver power supply researched in this paper. It was made up by front-end converter whose output was a constant voltage and load converter whose output was a constant current. A two-state Boost PFC+DC/DC structure was applied to the front-end converter to meet the requirements of the power factor. The high efficiency half bridge LLC resonant converter was selected as the main topology. In order to calculate and design better, the working principle of the two ZVS work region was analyzed in this paper. Then the FHA model was built, and the DC gain characteristic was analyzed. The conclusion was that the peak gain was the guarantee of half bridge LLC resonant converter normal operation. Under the limit of the peak gain, different k numerical values corresponded to different LLC resonant cavity parameters. Simulation circuit was built on the Saber simulation software, and simulations were implemented respectively when k=4,k=7and k=12. Four different cases, rated input and full load,minimum input and full load, maximum input and full load, maximum input and no load, were simulated for each parameter. By analyzing of the simulation waveforms, recording the data parameters and comparing, the final LLC resonant cavity parameters were determined. LLC integrated transformer was designed according to the requirements of the resonant cavity parameters.LED street light driver power supply circuit was consisted of front-end converter and load converter. The front-end converter was designed around the control chip PLC810PG. The input was85V～265V general mains power supply, and the output was48V constant bus voltage. The load converter was designed around the step down and constant current control chip TPS92510. The input was the bus voltage, and the output was1.05constant current. Each load was consisted of301W white LED, the load structure was3in parallel and10in series. A200W front-end converter could drive at least six load converters to constitute a power supply system. Front-end converter and load converter all had perfect protection functions, which could completely meet the circuit protection requirements of LED drive power supply. Verified by actual test and analysis, the LED driver power supply system designed in this paper could meet the requirements of the output parameters, efficiency and protection.