Research And Realization Of LED Drived Power Supply Based On PFC

Along with the rapid development of computer technology and power electronics,power supply equipment become more and more popular. On one hand,a huge numberof electronic equipments in the AC power grid constantly switch on and off, resulting inlarge amount of harmonic order. In order to control the harmonic pollution, power factorcorrection (PFC) technique is added into the circuits to reduce the input currentharmonics, thus the harmonic pollution on the grid is greatly improved. On the otherhand, due to growing efficiency requirements, many power supply manufacturers diverttheir energy to PFC topology study. In general, the PFC circuit can reduce conductionloss by decreasing the amount of semiconductor components in line current path.Overall, because of good performance and lowly cost, PFC technology is widely used,with good market prospects as well. Meanwhile, a variety of power factor correctiontechnology is further developed.With the emergence of new applications, PFC technology research is still facingmany challenges, LED illumination is a typical case. In line with the trend of energysaving and environmental protection, LED illumination has characteristics and uniquerequirements as below: long lifetime, high reliability, SCR phased dimming,single-stage electrical isolation, optical dimming and so on.This paper introduces human lighting history, analyzing the prospects LED. Basedon basic characteristics and advantage, several driving modes of LED are summarizedand compared. Then, research on LED drive power supply unit is introduced. Afterprofound analyzing characteristics and topology of the LED drive power supply,classification and application of LED switching power supply are presented in detail,constituting the main body of the paper. PFC technology can improve the AC/DCconverter input power factor and reduce harmonic pollution, LED drive power based onPFC design and implementation is of great significance in terms of energy conservation,resource conservation and environmental protection, meanwhile, demonstrating thevalue and practical significance of this thesisThis paper discusses a kind of LED drive power using PFC circuit by comparing and analyzing its control methods and classifications. Finally, a CRM mode of PFCdesign is raised after introduction of pin definitions and features of L6562and L6565,including preceding stage power factor correction, lightning surge protection, EMIcircuit, final stage DC/DC converter for voltage conversion, to meet the requirements ofthe constant current regulation input voltage and maintain constant current output, torealize normal operation of LED. Protecting function is set according to thecharacteristics of LED. In this paper, design methods and procedures are presented,including key technology and solutions in the program. Meanwhile, deficit of the thesisanalyzed and thesis design experiences shared. All the experiment data listed showingthat experiment meet application requirements and testify all the theory analysis. Finally,future research direction is figured out, including life period, reliability and human ofpower supply.