外文翻译开关电源半桥和全桥变换器拓扑(适用于毕业论文外文翻译_第1页
外文翻译开关电源半桥和全桥变换器拓扑(适用于毕业论文外文翻译_第2页
外文翻译开关电源半桥和全桥变换器拓扑(适用于毕业论文外文翻译_第3页
外文翻译开关电源半桥和全桥变换器拓扑(适用于毕业论文外文翻译_第4页
外文翻译开关电源半桥和全桥变换器拓扑(适用于毕业论文外文翻译_第5页
全文预览已结束

下载本文档

版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领

文档简介

W功率因数校正开关电源的研究与设计外文翻译SWITCHINGPOWERSUPPLYDESIGN开关电源设计CHAPTER3HALFANDFULLBRIDGECONVERTERTOPOLOGIES31INTRODUCTIONHALFBRIDGEANDFULLBRIDGETOPOLOGIESSTRESSTHEIRTRANSISTORSTOAVOLTAGEEQUALTOTHEDCINPUTVOLTAGENOTTOTWICETHISVALUEASDOTHEPUSHPULLSINGLEENDEDANDINTERLEAVEDFORWARDCONVERTERTOPOLOGIESTHUSTHEBRIDGETOPOLOGIESAREUSEDMAINLYINOFFLINECONVERTERSWHERESUPPLYVOLTAGEWOULDBEMORETHANTHESWITCHINGTRANSISTORSCOULDSAFELYTOLERATEBRIDGETOPOLOGIESAREALMOSTALWAYSUSEDWHERETHENORMALACINPUTVOLTAGEIS220VORHIGHERANDFREQUENTLYEVENFOR120VACINPUTSANADDITIONALVALUABLEFEATUREOFTHEBRIDGETOPOLOGIESISTHATPRIMARYLEAKAGEINDUCTANCESPIKESFIGURES21AND210AREEASILYCLAMPEDTOTHEDCSUPPLYBUSANDTHEENERGYSTOREDINTHELEAKAGEINDUCTANCEISRETURNEDTOTHEINPUTINSTEADOFHAVINGTOBEDISSIPATEDINARESISTIVESNUBBERELEMENT32HALFBRIDGECONVERTERTOPOLOGY321BASICOPERATIONHALFBRIDGECONVERTERTOPOLOGYISSHOWNINFIGURE31ITSMAJORWADVANTAGEISTHATLIKETHEDOUBLEENDEDFORWARDCONVERTERITSUBJECTSTHE“OFF”TRANSISTORTOONLYVDCANDNOTTWICETHATVALUETHUSITISWIDELYUSEDINEQUIPMENTINTENDEDFORTHEEUROPEANMARKETWHERETHEACINPUTVOLTAGEIS220VFIRSTCONSIDERTHEINPUTRECTIFIERANDFILTERINFIGURE31ITISUSEDUNIVERSALLYWHENTHEEQUIPMENTISTOWORKFROMEITHER120VACAMERICANPOWEROR220VACEUROPEANPOWERTHECIRCUITALWAYSYIELDSROUGHLY320VRECTIFIEDDCVOLTAGEWHETHERTHEINPUTIS120ORFIGURE31HALFBRIDGECONVERTERONEENDOFTHEPOWERTRANSFORMERPRIMARYISCONNECTEDTOTHEWJUNCTIONOFFILTERCAPACITORSC1C2VIAASMALLDCLOCKINGCAPACITORCBTHEOTHERENDISCONNECTEDTOTHEJUNCTIONOFQ1Q2WHICHTURN“ON”AND“OFF”ONALTERNATEHALFCYCLESWITHS1INTHECLOSEDPOSITIONTHECIRCUITISAVOLTAGEDOUBLERINTHEOPENPOSITIONITISAFULLWAVERECTIFIERINEITHERCASETHERECTIFIEDOUTPUTISABOUT308TO336VDC220VACITDOESTHISWHENSWITCHS1ISSETTOTHEOPENPOSITIONFOR220VACINPUTORTOTHECLOSEDPOSITIONFOR120VACINPUTTHES1COMPONENTISNORMALLYNOTASWITCHMOREOFTENITISAWIRELINKTHATISEITHERINSTALLEDFOR120VACORNOTFOR220VACWITHTHESWITCHINTHEOPEN220VACPOSITIONTHECIRCUITISAFULLWAVERECTIFIERWITHFILTERCAPACITORSC1ANDC2INSERIESITPRODUCESAPEAKRECTIFIEDDCVOLTAGEOFABOUT1412202OR308VWHENTHESWITCHISINTHECLOSED120VACPOSITIONTHECIRCUITACTSASAVOLTAGEDOUBLERONEHALFCYCLEOFTHEINPUTVOLTAGEWHENAISPOSITIVERELATIVETOBC1ISCHARGEDPOSITIVELYVIAD1TOAPEAKOF1411201OR168VONAHALFCYCLEWHENAISNEGATIVEWITHRESPECTTOBCAPACITORC2ISCHARGEDPOSITIVELYVIAD2TO168VTHETOTALVOLTAGEACROSSC1ANDC2INSERIESISTHEN336VITCANBESEENINFIGURE31THATWITHEITHERTRANSISTOR“ON”THE“OFF”TRANSISTORISSUBJECTEDTOTHEMAXIMUMDCINPUTVOLTAGEANDNOTTWICETHATVALUESINCETHETOPOLOGYSUBJECTSTHE“OFF”TRANSISTORTOONLYVDCANDNOT2VDCTHEREAREMANYINEXPENSIVEBIPOLARANDMOSFETTRANSISTORSTHATCANSUPPORTTHENOMINAL336DCVPLUS15UPPERMAXIMUMOF386VTHUSTHEEQUIPMENTCANBEUSEDWITHEITHER120OR220VACLINEINPUTSBYMAKINGASIMPLESWITCHORLINKAGECHANGEASSUMINGANOMINALRECTIFIEDDCVOLTAGEOF336VTHETOPOLOGYWORKSASWFOLLOWSFORTHEMOMENTIGNORETHESMALLSERIESBLOCKINGCAPACITORCBASSUMETHEBOTTOMENDOFNPISCONNECTEDTOTHEJUNCTIONOFC1ANDC2THENIFTHELEAKAGESINC1C2AREASSUMEDTOBEEQUALTHATPOINTWILLBEATHALFTHERECTIFIEDDCVOLTAGEABOUT168VITISGENERALLYGOODPRACTICETOPLACEEQUALBLEEDERRESISTORSACROSSC1ANDC2TOEQUALIZETHEIRVOLTAGEDROPSNOWQ1ANDQ2CONDUCTONALTERNATEHALFCYCLESWHENQ1IS“ON”ANDQ2“OFF”FIGURE31THEDOTENDOFNPIS168VPOSITIVEWITHRESPECTTOITSNODOTENDANDTHE“OFF”STRESSONQ2ISONLY336VWHENQ2IS“ON”ANDQ1“OFF”THEDOTENDOFNPIS168VNEGATIVEWITHRESPECTTOITSNODOTENDANDTHEEMITTEROFQ1IS336VNEGATIVEWITHRESPECTTOITSCOLLECTORTHISACSQUAREWAVEPRIMARYVOLTAGEPRODUCESFULLWAVESQUAREWAVESHAPESONALLSECONDARIESEXACTLYLIKETHESECONDARYVOLTAGESINTHEPUSHPULLTOPOLOGYTHESELECTIONOFSECONDARYVOLTAGESANDWIRESIZESANDTHEOUTPUTINDUCTORANDCAPACITORPROCEEDEXACTLYASFORTHEPUSHPULLCIRCUIT322HALFBRIDGEMAGNETICS3221SELECTINGMAXIMUM“ON”TIMEMAGNETICCOREANDPRIMARYTURNSITCANBESEENINFIGURE31THATIFQ1ANDQ2ARE“ON”SIMULTANEOUSLYEVENFORAVERYSHORTTIMETHEREISASHORTCIRCUITACROSSTHESUPPLYVOLTAGEANDTHETRANSISTORSWILLBEDESTROYEDTOMAKESURETHATTHISDOESNOTHAPPENTHEMAXIMUMQ1ORQ2“ON”TIMEWHICHOCCURSATMINIMUMDCSUPPLYVOLTAGEWILLBESETAT80OFAHALFPERIODTHESECONDARYTURNSWILLBECHOSENSOTHATWTHEDESIREDOUTPUTVOLTAGESAREOBTAINEDWITHAN“ON”TIMEOFNOMORETHAN08T/2AN“ON”TIMECLAMPWILLBEPROVIDEDTOENSURETHATTHE“ON”TIMECANNEVERBEGREATERTHAN08T/2UNDERFAULTORTRANSIENTCONDITIONSTHECOREISSELECTEDFROMTHETABLESINCHAPTER7MENTIONEDEARLIERTHESETABLESGIVEMAXIMUMAVAILABLEOUTPUTPOWERASAFUNCTIONOFOPERATINGFREQUENCYPEAKFLUXDENSITYCOREANDIRONAREASANDCOILCURRENTDENSITYWITHACORESELECTEDANDITSIRONAREAKNOWNTHENUMBEROFPRIMARYTURNSISCALCULATEDFROMFARADAYSLAWEQ117USINGTHEMINIMUMPRIMARYVOLTAGEVDC/21ANDTHEMAXIMUM“ON”TIMEOF08T/2HERETHEFLUXEXCURSIONDBINTHEEQUATIONISTWICETHEDESIREDPEAKFLUXDENSITY1600GBELOW50KHZORLESSATHIGHERFREQUENCYBECAUSETHEHALFBRIDGECOREOPERATESINTHEFIRSTANDTHIRDQUADRANTSOFITSHYSTERESISLOOPUNLIKETHEFORWARDCONVERTERSECTION239WHICHOPERATESINTHEFIRSTQUADRANTONLY3222THERELATIONBETWEENINPUTVOLTAGEPRIMARYCURRENTANDOUTPUTPOWERIFWEASSUMEANEFFICIENCYOF80THENPIN125POTHEINPUTPOWERATMINIMUMSUPPLYVOLTAGEISTHEPRODUCTOFMINIMUMPRIMARYVOLTAGEANDAVERAGEPRIMARYCURRENTATMINIMUMDCINPUTATMINIMUMDCINPUTTHEMAXIMUM“ON”TIMEINEACHHALFPERIODWILLBESETAT08T/2ASDISCUSSEDABOVEANDTHEPRIMARYHASTWOCURRENTPULSESOFWIDTHW08T/2PERPERIODTATPRIMARYVOLTAGEVDC/2THEINPUTPOWERIS125POVDC/2IPFT08T/TWHEREIPFTISTHEPEAKEQUIVALENTFLATTOPPEDPRIMARYCURRENTPULSETHENIPFTHALFBRIDGE313P0/VDC313223PRIMARYWIRESIZESELECTIONPRIMARYWIRESIZEMUSTBEMUCHLARGERINAHALFBRIDGETHANINAPUSHPULLCIRCUITOFTHESAMEOUTPUTPOWERHOWEVERTHEREARETWOHALFPRIMARIESINTHEPUSHPULLEACHOFWHICHHASTOSUPPORTTWICETHEVOLTAGEOFTHEHALFBRIDGEPRIMARYWHENOPERATEDFROMTHESAMESUPPLYVOLTAGECONSEQUENTLYCOILSIZESFORTHETWOTOPOLOGIESARENOTMUCHDIFFERENTHALFBRIDGEPRIMARYRMSCURRENTISIRMSIPFTANDFROMEQ31IRMS279PO/VDC32AT500CIRCULARMILSPERRMSAMPERETHEREQUIREDNUMBEROFCIRCULARMILSISCIRCULARMILSNEEDED500279PO/VDC1395PO/VDC333224SECONDARYTURNSANDWIRESIZESELECTIONINTHEFOLLOWINGTREATMENTTHENUMBEROFSECONDARYTURNSWILLBESELECTEDUSINGEQS21TO23FORTON08T/2ANDTHETERMVDC1WILLBEREPLACEDBYTHEMINIMUMPRIMARYVOLTAGEWHICHISVDC/21THESECONDARYRMSWCURRENTSANDWIRESIZESARECALCULATEDFROMEQS213AND214EXACTLYASFORTHEFULLWAVESECONDARIESOFAPUSHPULLCIRCUIT323OUTPUTFILTERCALCULATIONSTHEOUTPUTINDUCTORANDCAPACITORARESELECTEDUSINGEQS220AND222ASINAPUSHPULLCIRCUITFORTHESAMEINDUCTORCURRENTRAMPAMPLITUDEANDDESIREDOUTPUTRIPPLEVOLTAGE324BLOCKINGCAPACITORTOAVOIDFLUXIMBALANCETOAVOIDTHEFLUXIMBALANCEPROBLEMDISCUSSEDINCONNECTIONWITHTHEPUSHPULLCIRCUITSECTION225ASMALLCAPACITORCBISFITTEDINSERIESWITHTHEPRIMARYASINFIGURE31RECALLTHATFLUXIMBALANCEOCCURSIFTHEVOLTSECONDPRODUCTACROSSTHEPRIMARYWHILETHECOREISSETMOVESINONEDIRECTIONALONGTHEHYSTERESISLOOPDIFFERSFROMTHEVOLTSECONDPRODUCTAFTERITMOVESINTHEOPPOSITEDIRECTIONTHUSIFTHEJUNCTIONOFC1ANDC2ISNOTATEXACTLYHALFTHESUPPLYVOLTAGETHEVOLTAGEACROSSTHEPRIMARYWHENQ1IS“ON”WILLDIFFERFROMTHEVOLTAGEACROSSITWHENQ2IS“ON”ANDTHECOREWILLWALKUPORDOWNTHEHYSTERESISLOOPEVENTUALLYCAUSINGSATURATIONANDDESTROYINGTHETRANSISTORSTHISSATURATINGEFFECTCOMESABOUTBECAUSETHEREISANEFFECTIVEDCCURRENTBIASINTHEPRIMARYTOAVOIDTHISDCBIASTHEBLOCKINGCAPACITORISPLACEDINSERIESINTHEPRIMARYTHECAPACITORVALUEISSELECTEDWFIGURE32THESMALLBLOCKINGCAPACITORCBINSERIESWITHTHEHALFBRIDGEPRIMARYFIGURE31ISNEEDEDTOPREVENTFLUXIMBALANCEIFTHEJUNCTIONOFTHEFILTERCAPACITORSISNOTATEXACTLYTHEMIDPOINTOFTHESUPPLYVOLTAGEPRIMARYCURRENTCHARGESTHECAPACITORCAUSINGADROOPINTHEPRIMARYVOLTAGEWAVEFORMTHISDROOPSHOULDBEKEPTTONOMORETHAN10THEDROOPINPRIMARYVOLTAGEDUETOTHEOFFSETCHARGINGOFTHEBLOCKINGCAPACITORISSHOWNASDVASFOLLOWSTHECAPACITORCHARGESUPASTHEPRIMARYCURRENTIPFTFLOWSINTOITROBBINGVOLTAGEFROMTHEFLATTOPPEDPRIMARYPULSESHOWNINFIGURE32THISDCOFFSETROBSVOLTSECONDSFROMALLSECONDARYWINDINGSANDFORCESALONGER“ON”TIMETOACHIEVETHEDESIREDOUTPUTVOLTAGEINGENERALITISDESIRABLETOKEEPTHEPRIMARYVOLTAGEPULSESASFLATTOPPEDASPOSSIBLEINTHISEXAMPLEWEWILLASSUMEAPERMISSIBLEDROOPOFDVTHEEQUIVALENTFLATTOPPEDCURRENTPULSETHATCAUSESTHISDROOPISIPFTINEQ31THENBECAUSETHATCURRENTFLOWSFOR08T/2THEREQUIREDCAPACITORMAGNITUDEISSIMPLYCB34CONSIDERANEXAMPLEASSUMINGA150WHALFBRIDGEOPERATINGAT100KHZFROMANOMINALDCINPUTOF320VAT15LOWLINETHEDCINPUTIS272VANDTHEPRIMARYVOLTAGEIS272/2OR136VATOLERABLEDROOPINTHEFLATTOPPEDPRIMARYVOLTAGEPULSEWOULDWBE10ORABOUT14VTHENFROMEQ31FOR150WANDVDCOF272VIPFT313150/272173AANDFROMEQ34CB173085106/14049FTHECAPACITORMUSTBEANONPOLARIZEDTYPE325HALFBRIDGELEAKAGEINDUCTANCEPROBLEMSLEAKAGEINDUCTANCESPIKESWHICHARESOTROUBLESOMEINTHESINGLEENDEDFORWARDCONVERTERANDPUSHPULLTOPOLOGYAREEASILYAVOIDEDINTHEHALFBRIDGETHEYARECLAMPEDTOVDCBYTHECLAMPINGDIODESD5D6ACROSSTRANSISTORSQ1Q2ASSUMINGQ1IS“ON”THELOADANDMAGNETIZINGCURRENTSFLOWTHROUGHITANDTHROUGHTHEPRIMARYLEAKAGEINDUCTANCEOFT1THEPARALLELEDT1MAGNETIZINGINDUCTANCEANDTHESECONDARYLOADIMPEDANCESTHATAREREFLECTEDBYTHEIRTURNRATIOSSQUAREDINTOTHEPRIMARYTHENITFLOWSTHROUGHCBINTOTHEC1C2JUNCTIONTHEDOTENDOFNPISPOSITIVEWITHRESPECTTOITSNODOTENDWHENQ1TURNS“OFF”THEMAGNETIZINGINDUCTANCEFORCESALLWINDINGPOLARITIESTOREVERSETHEDOTENDOFT1STARTSTOGONEGATIVEBYFLYBACKACTIONANDIFTHISWERETOCONTINUEITWOULDPUTMORETHANVDCACROSSQ1ANDCOULDDAMAGEITALSOQ2COULDBEDAMAGEDBYIMPOSINGAREVERSEVOLTAGEACROSSITHOWEVERTHEDOTENDOFT1ISCLAMPEDBYDIODED6TOTHESUPPLYRAILVDCANDCANGONOMORENEGATIVETHANTHENEGATIVEENDOFTHESUPPLYSIMILARLYWHENQ2IS“ON”ITSTORESCURRENTINTHEMAGNETIZINGWINDUCTANCEANDTHEDOTENDOFNPISNEGATIVEWITHRESPECTTOTHENODOTENDWHICHISCLOSETOVDC/2WHENQ2TURNS“OFF”THEMAGNETIZINGINDUCTANCEREVERSESALLWINDINGPOLARITIESBYFLYBACKACTIONANDTHEDOTENDOFNPTRIESTOGOPOSITIVEBUTISCAUGHTATVDCBYCLAMPDIODED5THUSTHEENERGYSTOREDINTHELEAKAGEINDUCTANCEDURINGTHE“ON”TIMEISRETURNEDTOTHESUPPLYRAILVDCVIADIODESD5D6译文第三章半桥和全桥变换器拓扑31概述半桥和全桥拓扑开关管的稳态关断电压等于直流输入电压,而不像推挽、单端正激或交错正激拓扑那样为电压的两倍。所以桥式拓扑广泛用于直接电网的离线式变换器。而对推挽等拓扑来说,两倍的电网整流电压将超过其开关管的安全耐压容限。为此,输入网压为220V或更高的场合几乎都使用桥式拓扑。当输入网压为120V时也有使用桥式拓扑的情况。桥式拓扑的另一优点是,能将变压器初级侧的漏感尖峰电压(如图21和图210所示)箝位于直流母线电压,并将漏感储存的能量归还到输入母线,而不是消耗于电阻元件。32半桥变换器拓扑321工作原理半桥变换器拓扑结构如图31所示。其主要优点是,开关管关断时承受电压为VDC(与双端正激变换器相同),而不是像推挽拓扑或是单端正激变换器那样为2VDC。因此,该拓扑在网压为220V的欧洲市场设备中得到W广泛应用。首先看图31中的输入整流和滤波部分。当要求设备适应不同的网压(120VAC(美国)或220VAC欧洲)时,这是一种普遍采用的方案。不管输入网压是120VAC还是220VAC,该电路整流得到的直流电压均为320V。当输入网压为220VAC时,S1断开;为120VAC时,S1闭合。事实上S1并不是实际的开关,而是一个根据不同输入而闭合或断开的接点。S1断开时,输入为220V交流电压,电路为全波整流电路,滤波电容C1和C2串联,整流得到的直流电压峰值约为141X2202308V;当S1闭合时,输入为120V交流电压,电路相当于一个倍压整流器。在输入电压的正半周,A点相对于B点为正,电源鼶1给C1充电,C1电压为上正下负,

温馨提示

  • 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
  • 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
  • 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
  • 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
  • 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
  • 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
  • 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

评论

0/150

提交评论