小功率开关电源设计1

兰州交通大学博文学院毕业设计（论文）摘要随着电力电子技术的发展，开关电源逐渐取代了线性电源，称为当今电源的主流形式，在电力、电器等领域中得到广泛应用。本论文是通过开关电源集成控制芯片M51995AFP设计制作的一种降压型开关电源，输出电压5VDC。此开关电源是通过脉宽调制技术控制接通占空比来调整输出电压，达到稳定输出目的的。论文主要完成了以下内容：(1)根据需要选择开关电源拓扑结构；(2)基于M51995AFP设计开关电源的控制核心部分；(3)设计整流滤波电路，减小输出纹波；(4)建立开关电源的电路模型并分析；(5)选择控制模型并仿真分析，确定系统参数。本论文根据控制芯片内各部件的工作原理，设计了合理的辅助电路，通过计算和仿真分析，得到了系统优化参数。掌握了开关电源设计的核心技术，并对设计过程做了详细阐述。关键词：开关电源占空比脉宽调制兰州交通大学博文学院毕业设计（论文）ABSTRCTWiththedevelopmentofpowerelectronicstechnology,switchingpowersupplyisgraduallyreplacedbyalinearpowersupply,knownasthemainstreamformoftoday'spowersupply,andiswidelyusedinelectricity,electronicsandotherfields.ThispaperisaswitchingpowersupplyintegratedthecontrolchipM51995AFPdesignastep-downswitchingpowersupply,theoutputvoltageof5VDC.Thisswitchingpowersupplyisondutythroughpulsewidthmodulationcontroltoadjusttheoutputvoltagetoachieveastableoutputpurposes.Thethesis,completedthefollowing:(1)Needtoselecttheswitchingpowersupplytopology;(2)BasedonthedesignofswitchingpowersupplycontrolcoreM51995AFPpart;(3)Designrectifierfiltercircuitreducestheoutputripple;(4)Theestablishmentoftheswitchingpowersupplycircuitmodelandanalysis;(5)Selectthemodelandsimulationanalysistodeterminethesystemparameters.Thisthesisisbasedontheworksofthevariouscomponentswithinthecontrolchipdesignreasonableauxiliarycircuit,calculationandsimulationanalysis,systemtuningparameters.Masteredthecoretechnologyoftheswitchingpowersupplydesign,andthedesignprocesselaborate.Keywords:SwitchingPowerSupplyDutyCyclePulseWidthModulation兰州交通大学博文学院毕业设计（论文）目录1.绪论.................................................................................................................................11.1开关电源的概念和分类............................................................................................11.1.1开关电源的概念..............................................................................................11.1.2开关电源的分类..............................................................................................22.开关电源的设计基础.........................................................................................................42.1开关电源中的电力电子电路....................................................................................42.1.1非隔离型电路..................................................................................................42.1.2隔离型电路......................................................................................................62.2软开关技术................................................................................................................82.2.1零电压开关和零电流开关..............................................................................82.2.2常见软开关电路..............................................................................................92.3谐振式电源................................................................................................................92.3.1谐振变换电路的原理及分类..........................................................................92.3.2谐振式电源原理............................................................................................103.开关电源元器件的选用...................................................................................................113.1二极管......................................................................................................................113.1.1开关二极管....................................................................................................113.1.2稳压二极管....................................................................................................113.1.3快速恢复及超快速恢复二极管....................................................................123.2开关晶体管..............................................................................................................123.2.1功率开关MOSFET.......................................................................................123.2.2绝缘栅双极型晶体管....................................................................................143.3自动恢复开关..........................................................................................................143.5光电耦合器..............................................................................................................153.6软磁铁软体磁芯......................................................................................................173.7磁芯的选用..............................................................................................................174.开关电源设计...................................................................................................................184.1开关电源集成控制器..............................................................................................184.1.1芯片管脚排列................................................................................................18兰州交通大学博文学院毕业设计（论文）4.1.2芯片的基本特性............................................................................................184.1.3芯片工作原理................................................................................................194.2开关电源电路分析.......................