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1、SwitchingPowerSupplySwitchingpowersupplyisavoltageconversioncircuit,themainworkisthestep-upandstep-down,arewidelyusedinmodernelectronicproducts.Alwaysworkbecausetheswitchingtransistorintheonandoffstate,socalledswitchingpowersupply.Switchingpowersupplyinrealtermsisanoscillatorcircuit,theconversionofe
2、lectricalenergynotonlyusedinpowercircuit,thecircuitinotherapplicationsarealsocommon,suchasLCDbacklightcircuits,suchasfluorescentlamps.Switchthesourcecomparedwiththetransformerhighefficiency,goodstability,smallsizeandotheradvantages,disadvantagesistherelativelysmallpower,andhigh-frequencyinterference
3、onthecircuit,circuitcomplexity,suchaseasymaintenance.Talkingaboutswitchingpowersupplybeforeyoufamiliarwiththefeedbackoscillatorcircuittransformer,canproducearegularpulsecurrentorvoltageofthecircuitiscalledoscillationcircuit,transformerfeedbackoscillatorcircuitisabletomeettheseconditionsthecircuit；it
4、inthebasicamplifiercircuitwithafeedbackloopcomposedofC2,L1electiontoformaparallelresonantfrequencycircuit,theinstantaneouspowerinthecircuitturn-VT,thistimeintheC2,L1,composedofparallelresonantcircuitshaveaveryrichharmonic,whentheplusparallelresonancefrequencyandthenaturalfrequencyofthesamecircuit,th
5、ecircuittoenterastateofoscillation,andVTthroughL3feedbacktofurtherenlargethebase,andultimatelytheformationofaregularpulsecurrentorvoltageoutputtotheloadRL.Switchingpowersupplyisaroundthetransformerandthefeedbackoscillatorcircuitdesign,butthebasisoftheoriginalincreaseinthenumberofprotectionandcontrol
6、circuits,analysisofouroscillationcircuitcanbeusedtoanalyzethemethodofswitchingpowersupply.SwitchingPowerSupplyvibrationbywayofsub-swingcanbedividedintoself-excitedanditexcitedthetwo,sincethereisnoneedforplus-excitedself-oscillationsignalsource,sincetheexcitationcanseeitasafeedbackoscillatorcircuittr
7、ansformer,anditisexcitedistotallydependentontheoutsidetomaintaintheoscillation,inthepracticalapplicationofself-excitationofacomprehensiverangeofapplications.Accordingtothestructureofincentivessignalclassification；canbedividedintopulse-width-modulatedpulseamplitudemodulationandtwopulse-width-modulate
8、dsignaltocontrolthewidth,thatis,frequency,pulseamplitudemodulationcontrolsignalofthemagnitudeoftheroleofthetwothesamesothatoscillationfrequencyismaintainedatwithinacertainrange,totheeffectofvoltagestability.Windingtransformercanbedividedintothreetypesingeneral,agroupinvolvedintheprimarywindingoftheo
9、scillation,agroupistomaintaintheoscillationofthefeedbackwinding,thereisagroupoftheloadwindings.Householdappliancesusedinswitchingpowersupply,aftertheACto220Vbridgerectifier,convertedintoabout300VDC,filterintothetransformerisaddedaftertheswitchtohigh-frequencyoscillationsofthecollector,feedbackwindin
10、gbacktothebasetomaintaintheoscillationcircuit,loadsensorwindingsoftheelectricalsignal,byrectification,filtering,theDCvoltageregulatorhasbeentoprovidepowertotheload.Windingintheprovisionofelectricpowerload,butalsotakeupthecapacityofvoltagestability,thetheoryisthenacircuitvoltageoutputvoltagesamplingd
11、evicestomonitortheoutputvoltagechanges,timelyfeedbacktoadjusttheoscillationfrequencyoscillatorcircuittoachievethevoltagestabilityThepurposeofthecircuitinordertoavoidinterference,thefeedbackvoltagetotheoscillatorcircuitwillbeisolatedoptocoupler.Mostswitcheshaveastandbypowercircuit,switchingpowersuppl
12、yinstandbymodestilloscillating,butthefrequencyofnormalworkinghoursthanlower.Someswitchingpowersupplyarecomplex,numerouscomponents,manyprotectionandcontrolcircuit,intheabsenceoftechnicalsupport,maintenanceisaheadachewiththematter.Ifacethiskindofsituationis,firstofall,Iwillfindtheswitchanditsparticipa
13、tionintheexternaloscillationcircuit,itseparatedfromthecircuittoseeifitmettheconditionsforoscillation,suchasdetectionbiasandwhetheritisnormal,whetherpositivefeedbackfailure,aswellasitsownswitches,switchingpowersupplyhasverylargeprotection,afterexclusionoftheprosecutionandloadcontrolandprotectioncircu
14、it.thecontrolcircuitwhileoutputfromthesample,withthesetstandards,thencontrolledinverter,changeitsfrequencyorpulsewidthoutputachievestability,ontheotherhand,accordingtotestdataprovidedbythecircuitbycircuitprotectionidentification,Controlcircuitfortheunitforvariousprotectionmeasures.SMPSdevelopmentsan
15、dtrendsintheUnitedStatesin1955Roje(GH.Roger)inventionoftheself-excitedoscillationpushredeemtransistorsingletransformerDCconverters,high-frequencyconversionisthebeginningofcontrolcircuit,1957UnitedStatesinvestigationtournament(JenSen)sincetheinventionofthepush-pulldoubleFlybacktransformers,1964Americ
16、anscientistsproposestoabolishthefrequencytransformerseriesswitchingpowersupplyscenario,Thispowertotherightsizeandweightofthedeclinewasafundamentalway.Tothe1969high-powersilicontransistorbecausethepressureincreasediodereverserecoverytimeshortened,andothercomponentsimprove,andfinallyturnedintoa25kHzsw
17、itchingpowersupply.Currently,switchingpowersupplytosmall,Lightvolumeandthecharacteristicsofhighefficiencyhasbeenwidelyusedinelectroniccomputer-drivenvarietyofterminalequipment,Communicationsequipmentalmostallelectronicequipment,theelectronicinformationindustryindispensabletotherapiddevelopmentofapow
18、ermode.Currentlythemarketforsaleintheswitchingpowersupplyusingbipolartransistorsmadeof100kHz.usemadeof500kHzMOSpower,thoughpractical,butitsfrequencytobefurtherenhanced.Toimprovetheswitchingfrequency,itisnecessarytoreducetheswitchingloss,andtoreducetheswitchingloss,youneedtohavehigh-speedswitchingdev
19、ices.However,theswitchingspeed,willbeaffectedbythecircuitinductanceandcapacitancediodeorstoredchargearisingfromtheimpactofthesurgeornoise.Thiswillnotonlyaffectthesurroundingelectronicequipment,butalsogreatlyreducethereliabilityofthepowersupplyitself.Amongthem,withtheswitchtopreventKai-closedbythevol
20、tagesurge,itisR-CorL-CCompositebumpers,andthestoragechargebythediodecurrentsurgecausedbytheusemadeofamorphouscoressuchasmagneticbumper.However,thehighfrequencyof1MHzandabove,usingresonantcircuit,Switchtoenablethevoltageorcurrentthroughtheswitchwasasine,whichcouldreducetheswitchingloss,Thiscanalsocon
21、trolthesurgeoccurred.Switchessuchasresonantmodeswitching.CurrentlysuchSMPSofveryactive,becausethismeansnosignificantincreaseswitchingspeedcantheoreticallyputswitchinglossfalltozero.andthenoiseissmall,isexpectedtobecomehigh-frequencyswitchingpowersupplyofoneofthemainways.Atpresent,manycountriesinthew
22、orldareworkingonseveraltrillionHzconverterpracticalresearch.開關(guān)電源開關(guān)電源是一種電壓轉(zhuǎn)換電路，主要的工作內(nèi)容是升壓和降壓，廣泛應(yīng)用于現(xiàn)代電子產(chǎn)品。因?yàn)殚_關(guān)三極管總是工作在“開”和“關(guān)”的狀態(tài)，所以叫開關(guān)電源。開關(guān)電源實(shí)質(zhì)就是一個振蕩電路，這種轉(zhuǎn)換電能的方式，不僅應(yīng)用在電源電路，在其它的電路應(yīng)用也很普遍，如液晶顯示器的背光電路、日光燈等。開關(guān)源與變壓器相比具有效率高、穩(wěn)性好、體積小等優(yōu)點(diǎn)，缺點(diǎn)是功率相對較小，而且會對電路產(chǎn)生高頻干擾，電路復(fù)雜不易維修等。在談開關(guān)電源之前，先熟悉一下變壓器反饋式振蕩電路，能產(chǎn)生有規(guī)律的脈沖電流或電壓的電
23、路叫振蕩電路，變壓器反饋式振蕩電路就是能滿足這種條件的電路；它于基本放大電路與一個反饋回路組成，其中C2、L1組成一個并聯(lián)諧振選頻電路，在電路通電的瞬間VT導(dǎo)通，此時在C2、L1組成的并聯(lián)諧振電路上產(chǎn)生非常豐富的諧波，當(dāng)外加頻率和并聯(lián)諧振電路的固有頻率相等時,電路進(jìn)入振蕩狀態(tài)，并通過L3反饋到VT的基極進(jìn)一步放大，最終形成有規(guī)律的脈沖電流或電壓輸出到負(fù)載RL上。開關(guān)電源就是圍繞變壓器反饋式振蕩電路而設(shè)計(jì)，只不過在原來的基礎(chǔ)上增加了一些保護(hù)和控制電路，我們可以用分析振蕩電路的方法來分析開關(guān)電源。開關(guān)電源振按蕩方式分，可以分為自激式和它激式兩種，自激式是無須外加信號源能自行振蕩，自激式完全可以把它
24、看作是一個變壓器反饋式振蕩電路，而它激式則完全依賴于外部維持振蕩，在實(shí)際應(yīng)用中自激式應(yīng)用比較廣泛。根據(jù)激勵信號結(jié)構(gòu)分類；可分為脈沖調(diào)寬和脈沖調(diào)幅兩種，脈沖調(diào)寬是控制信號的寬度，也就是頻率，脈沖調(diào)幅控制信號的幅度，兩者的作用相同都是使振蕩頻率維持在某一范圍內(nèi)，達(dá)到穩(wěn)定電壓的效果。變壓器的繞組一般可以分成三種類型，一組是參與振蕩的初級繞組，一組是維持振蕩的反饋繞組，還有一組是負(fù)載繞組。在家用電器中使用的開關(guān)電源，將220V的交流電經(jīng)過橋式整流，變換成300V左右的直流電，濾波后進(jìn)入變壓器后加到開關(guān)管的集電極進(jìn)行高頻振蕩，反饋繞組反饋到基極維持電路振蕩，負(fù)載繞組感應(yīng)的電信號，經(jīng)整流、濾波、穩(wěn)壓得到的直流電壓給負(fù)載提供電能。負(fù)載繞組在提供電能的同時，也肩負(fù)起穩(wěn)定電壓的能力，其原理是在電壓輸出電路接一個電壓取樣裝置，監(jiān)測輸出電壓的變化
中英翻譯--開關(guān)電源.doc
