Design Of High-power And Inteligent LED Power Supply

Since 21 st century, LED lighting has been developing quickly. To make LED light stability, its power supply system must be able to provide a constant DC current. At present,LED constant current drive power mostly uses the analog chips as the controller, in which the controlling circuit has a complicated structure and can be susceptible to electromagnetic environment interference and its reliability is not high, the output current cannot be changed and so on. Based on a digital control chip TMS320F28335, a full digital control LED constant current drive power supply is designed and compared to the traditional ones, it has simple circuits, high reliability, strong anti- interference ability, the advantages of large output current and especially the alterative output current which can be adapted to the use of different occasions.Firstly, the topology structures of traditional LED drive power supply are analyzed, and the advantages and disadvantages of the different structures are summed up. According to the power supply design requirements, the Saber simulation software for flyback topology has been used and the results is shown that the single traditional topology structure can not meet the design requirements. Therefore a combine structure of flyback converter and Buck circuit topology is proposed, and the Saber simulation results is shown that the power supply with the combine structure can precisely control the output current under high power and small power output.Subsequently, the hardware and software of the power supply are designed. The hardware parts include: EMI filter circuit, the protection circuit, Buck circuit, high frequency transformer, the input and output rectifier filter circuits, IGBT drive circuit, current and voltage sampling circuits and the power modules; the software parts includes: the configurations of ePWM modules and ADC modules, the selection of output current sampling point and the program of the PID algorithm.Finally, based on the combine structures of flyback and Buck circuit, a LED constant current drive power supply is finished. The output current, current rise time, current ripple under the conditions of zero- load and load and constant pressure patterns are tested respectively, and the test results is shown that the output current of the constant current power supply is stable, basically meet the design requirements of this article.