Research And Design Of High-power UV LED Power Supply System

Ultraviolet Light Emitting Diode(UV LED)has the advantages of high efficiency,energy saving and environmental protection,and is gradually replacing the traditional high-pressure mercury lamp.It is getting more and more attention and application in the optoelectronic solid market.In the UV LED curing system,the driving power supply is an important part,which deserves more attention and research.This research focuses on the current high power UV LED driver's low power density,poor dimming accuracy,light load operation instability and other problems.The main work and research methods are as follows:(1)Aiming at the problem of low power density and reliability of high-power UV LED driver at the kilowatt level,the characteristics of volume,cost and reliability of the existing drive schemes are analyzed and summarized.On this basis,the overall power supply architecture of three-phase independent input and two-stage multi-channel independent output is designed.Considering EMC,power factor correction,power efficiency and other factors,the circuit scheme of the front AC/DC is determined to be EMI filter circuit,Boost PFC circuit,LLC resonant circuit.Considering such factors as power,efficiency and Buck scheme,the poststage DC/DC scheme is determined to be a constant current Buck circuit.(2)To solve the problem of poor dimming accuracy of UV LED power supply,based on the design of the rear constant current driving power supply,a double closed-loop dimming scheme of Buck closed-loop constant current control on the hardware and PWM wave duty cycle on the software was completed.In the hardware aspect of the post-stage power supply,the parameter index is analyzed,and the parameter design and device selection of the Buck power circuit are completed.After analyzing and comparing several control chips,NCP1034 is determined as the control loop scheme of Buck converter,and the circuit parameters around the control chip are designed.In order to realize the functions of dimming,protection and communication,each functional unit circuit is designed.In the software aspect of the rear power supply,the program is designed based on MCU control board,and the closed-loop output PWM wave is realized.(3)In order to improve the output performance of UV LED rear stage power supply,the design and optimization method of MOS drive scheme was given.The driving resistance parameters were optimized by combining the specific MOS tube,and the correctness of the optimization method was verified by Saber simulation of the driving circuit under different parameters.The mechanism of how to run stably under very low load is studied,and two factors,PWM delay and loop parameters,are analyzed.In order to optimize the loop parameters,a small signal model was established for the post-stage converter,and the PI control parameters were analyzed and calculated.The rationality of the loop parameters and the good dynamic performance of the converter were verified by simulation.On the basis of the above research,a three-phase input and 15-channel output high-power supply system with a rated power of 4.5KW is built.The correctness of the scheme and the rationality of the parameters are verified by experiments.The research results of this topic have reference significance for the design of high power UV LED driving power with high power density,high precision dimming and stable operation under light load...