基于SG3525的半桥式开关电源变换器

I摘要电力电子及开关电源技术因应用需求不断向前发展，新技术的出现又会使许多应用产品更新换代，还会开拓更多更新的应用领域。要求电子元件体积更小，耗能更低。开关电源作为电子设备中不可或缺的组成部分也在不断的改进，高频化、高效率、高可靠、低耗、低噪声、抗干扰和模块化等，成了开关电源的发展方向，这也标志着这些技术将不断地发展而变得越来越成熟和稳定，同时实现高效率用电和高品质用电的相互结合。脉宽调制器SG3525具有欠压锁定、系统故障关闭、软起动、延时PWM驱动等功能，因而得到广泛应用。本设计介绍了一种基于SG3525的半桥式开关电源变换器，对其各电路工作原理进行了分析，并设计了过流保护电路。为了提高效率，辅助电源采用了UC3843为主控芯片的反激变换器。为了减低输入电磁干扰，输入端设置了EMI滤波电路。对各参数进行了计算，通过实物制作与调试证明了方案的可行性。该电源结构简单，思路清晰，运行稳定性好，有效降低了成本。关键词半桥SG3525过流保护IIAbstractTechnologyforpowerelectronicsandswitchingpowersupplyisgoingaheadcontinuouslyinpractice．Theemergenceofnewtechnologywillmakereplacementinmanyapplicationproductsaswellasopenupmoreandmorenewfields．Atthesametimecomponentsarerequiredtohavethesmallervolumeandlowerlosses，asanimportantpartsofelectronicdevicespowersupplyisgettingsomeimprovements，forhigh-frequency，forhighefficiency，forhighreliability，forlowlosses，forsmallnoise，foranti-interference，formoduleandsoon．Thesearebecomingadevelopmentdirectionforpowersupply，whichshowthatthesetechnologieswillbecomemorematureandstable，itwillachievethecombinabilitybetweenhigh-efficiencyandhighqualitytouseelectricenergy.ThepulsewidthmodulatorSG3525hasbeenusedinvariousareasforitsfunctionssuchaslockingforthelackofpressure,closingsystemfault,softstarting,delayingPWMdriveandsoon.Thisdesignintroducesahalf-bridgebasedonSG3525switchpowerconverte-r,theworkingprincipleofthecircuitisanalyzedanddesignedover-currentprotec-tioncircuit.Inordertoimproveefficiency,auxiliarypowerforthemainchipusedUC3843flybackconverter.Toreducetheinputofelectromagneticinterference,EMIinputfiltercircuitisset.eachparameterwascalculated,throughtheproducti-onandcommissioningphysicalproofthefeasibilityoftheproject.Thepowerstructureissimple,clear,runningstability,andeffectivelyreducingthecostofit.Keywords:half-bridgeSG3525overcurrentprotectionIII目录摘要.....................................................................................................................IAbstract.................................................................................................................II第1章绪论....................................................................................................11.1本课题研究的目的和意义..........................................................................11.2国内外技术发展概况..................................................................................11.321世纪开关电源的发展展望......................................................................21.4本设计的主要内容和目标..........................................................................41.5方案论证与总体设计..................................................................................41.5.1方案论证...............................................................................................41.5.2硬件总体结构设计...............................................................................6第2章半桥变换器拓扑分析.............................................................................72.1半桥变换器工作原理..................................................................................72.2半桥变换器的漏感问题..............................................................................8第3章控制芯片的介绍....................................................................................93.1SG3525工作特性分析.................................................................................93.2UC3843工作原理分析..............................................................................12第4章电路设计..............................................................................................164.1EMI滤波电路设计.....................................................................................164.2整流滤波电路设计....................................................................................184.3半桥电路设计............................................................................................194.4控制电路分析............................................................................................194.5驱动电路与过电流保护电路原理分析.....................................................204.5.1驱动电路设计.....................................................................................204.5.2过电流保护电路分析.........................................................................214.6辅助电源设计分析....................................................................................21第5章参数计算及主要元器件选择...............................................................23IV5.1主电路拓扑参数计算................................................................................235.1.1半桥变压器计算.................................................................................235.1.2电感的计算.........................................................................................255.1.3驱动变压器和电流互感器.................................................................285.2辅助电源变压器计算................................................................................285.3其他电路参数计算....................................................................................315.4主要芯片及元器件选择............................................................................33第6章测试数据与分析.................................