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1、本科毕业设计基于SG6848开关电源的设计32摘要开关电源是应用于广泛领域的一种电力电子装置。它具有电能转换效率高、体积小、重量轻、控制精度高和快速性好等优点，而传统的线性电源需要体积大且笨重的工频变压器和滤波器，而且其电源效率很低一般只有45%左右，还会产生大量的热量，所以在小功率范围内开关电源基本取代了线性电源，并迅速向大功率范围推进，在很大程度上取代了晶闸管相控整流电源。可以说，开关电源技术是目前中小功率直流电能变换装置的主流技术。为了设计高效率、高密度、高可靠性，重量轻的开关电源，就要去掉体积笨重的电
2、容、散热器和变压器，而集成IC的发展让设计理想的开关电源成为了可能。本文介绍了基于SG6848芯片的一种小功率开关电源的设计，将输入为90-270V、50/60Hz的交流电输入转换成5V、2A的直流电输出，用于对小功率电气的供电。本设计采用先进单片开关电源芯片SG6848，整个开关电源有控制电路，主电路拓扑，输入电路和输出电路构成。而控制电路采用PWM脉宽调制，主电路采用单端反激式开关电源。采用SG6848开关集成电路设计开关电源，缩小了开关电源的体积，简化了开关电源外围电路的设计，提高了开关电源的效率，降低
3、了开关电源的损耗，同时也使得开关电源更信息化，网络化。关键词：开关电源；PWM；SG684832AbstractSwitchingpowersupplyisusedinabroadrangeofpowerelectronicdevices.Ithashighenergyconversionefficiency,smallsize,lightweight,highcontrolprecisionandfastandgood,butthetraditionallinearpowersupplyrequiresbu
4、lkyandheavytransformerandfilterfrequency,anditspowerefficiencyisverylowgenerallyonly45%,butalsoproducelargeamountsofheat,sointhecontextoflowpowerswitchingpowersupplyreplacedthelinearpowersupply,andquicklyadvancingtohighpowerrange,toalargeextentreplacedtheth
5、yristorphase-controlledrectifierpowersupply.Itcanbesaid,switchingpowersupplytechnologyisthesmallandmedium-powerDCpowerconversiondeviceofthemainstream.Inordertodesignefficient,highdensity,highreliability,lightweightswitchpower,willremovethevolumeofcapacitor,
6、radiatorandcumbersome,andintegrationofICtransformerfordesignidealswitchpowerbecamepossible.ThispaperintroducesakindofSG6848chipsbasedonthedesignofsmallpowerswitchpowersupply,theinputfor90-270V,50/60Hzofalternatingcurrentinputconvert5Vdcoutput,and2Ausedforsm
7、allpowerelectricpowersupply.ThisdesignUSEStheadvancedmonolithicswitchingpowersupply,theswitchpowerSG6848chipshavecontrolcircuit,themaincircuittopology,inputcircuitandtheoutputcircuitconstitutes.AndcontrolcircuitusingPWMpulsewidthmodulation,themaincircuitUSE
8、Stheoclflybacktypeswitchpowersupply.UsingSG6848switchICdesignswitchingpowersupply,narrowedthevolumeofswitchpowersupply,simplifiesthedesignofbuffercircuitswitchpower,improvingtheefficiencyofswitchpowers
