小功率开关电源设计

小功率开关电源设计论文-1-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小功率开关电源设计论文-2-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:SwitchingPowerSupply,DutyCycle,PulseWidthModulation小功率开关电源设计论文-3-目录1.绪论........................................................................................................................-5-1.1开关电源的概念和分类..............................................................................-5-1.1.1开关电源的概念................................................................................-5-1.1.2开关电源的分类................................................................................-6-1.2开关电源的发展趋势..................................................................................-7-2.开关电源的设计基础............................................................................................-8-2.1开关电源中的电力电子电路......................................................................-8-2.1.1非隔离型电路....................................................................................-8-2.1.2隔离型电路......................................................................................-10-2.2软开关技术................................................................................................-12-2.2.1软开关的基本概念..........................................................................-12-2.2.2零电压开关和零电流开关..............................................................-14-2.2.3常见软开关电路..............................................................................-14-2.3谐振式电源................................................................................................-20-2.3.1谐振变换电路的原理及分类..........................................................-20-2.3.2谐振式电源原理..............................................................................-20-2.3.3谐振开关的动态过程分析..............................................................-21-3.开关电源元器件的选用......................................................................................-26-3.1二极管........................................................................................................-27-3.1.1开关二极管......................................................................................-27-3.1.2稳压二极管......................................................................................-27-3.1.3快速恢复及超快速恢复二极管......................................................-28-3.2开关晶体管................................................................................................-28-3.2.1功率开关MOSFET.........................................................................-28-3.2.2绝缘栅双极型晶体管......................................................................-30-3.3自动恢复开关............................................................................................-30-3.4热敏电阻....................................................................................................-31-3.5光电耦合器................................................................................................-32-3.6软磁铁软体磁芯........................................................................................-34-小功率开关电源设计论文-4-3.6.1磁性材料的基本特性............................................................................-34-3.6.2磁芯的选用及结构..............................................................................-35-4.开关电源设计......................................................................................................-35-4.1开关电源集成控制器................................................................................-35-4.1.1芯片管脚排列及说明......................................................................-36-4.1.2芯片的基本特性.............................................................................-37-4.1.3芯片工作原理....................................................