SwitchingPowerSupplySwitchingpowersupplyisavoltageconversioncircuit,themainworkisthestep-upandstep-down,arewidelyusedinmodernelectronicproducts.Alwaysworkbecausetheswitchingtransistorintheonandoffstate,socalledswitchingpowersupply.Switchingpowersupplyinrealtermsisanoscillatorcircuit,theconversionofelectricalenergynotonlyusedinpowercircuit,thecircuitinotherapplicationsarealsocommon,suchasLCDbacklightcircuits,suchasfluorescentlamps.Switchthesourcecomparedwiththetransformerhighefficiency,goodstability,smallsizeandotheradvantages,disadvantagesistherelativelysmallpower,andhigh-frequencyinterferenceonthecircuit,circuitcomplexity,suchaseasymaintenance.Talkingaboutswitchingpowersupplybeforeyoufamiliarwiththefeedbackoscillatorcircuittransformer,canproducearegularpulsecurrentorvoltageofthecircuitiscalledoscillationcircuit,transformerfeedbackoscillatorcircuitisabletomeettheseconditionsthecircuit；itinthebasicamplifiercircuitwithafeedbackloopcomposedofC2,L1electiontoformaparallelresonantfrequencycircuit,theinstantaneouspowerinthecircuitturn-VT,thistimeintheC2,L1,composedofparallelresonantcircuitshaveaveryrichharmonic,whentheplusparallelresonancefrequencyandthenaturalfrequencyofthesamecircuit,thecircuittoenterastateofoscillation,andVTthroughL3feedbacktofurtherenlargethebase,andultimatelytheformationofaregularpulsecurrentorvoltageoutputtotheloadRL.Switchingpowersupplyisaroundthetransformerandthefeedbackoscillatorcircuitdesign,butthebasisoftheoriginalincreaseinthenumberofprotectionandcontrolcircuits,analysisofouroscillationcircuitcanbeusedtoanalyzethemethodofswitchingpowersupply.SwitchingPowerSupplyvibrationbywayofsub-swingcanbedividedintoself-excitedanditexcitedthetwo,sincethereisnoneedforplus-excitedself-oscillationsignalsource,sincetheexcitationcanseeitasafeedbackoscillatorcircuittransformer,anditisexcitedistotallydependentontheoutsidetomaintaintheoscillation,inthepracticalapplicationofself-excitationofacomprehensiverangeofapplications.Accordingtothestructureofincentivessignalclassification；canbedividedintopulse-width-modulatedpulseamplitudemodulationandtwopulse-width-modulatedsignaltocontrolthewidth,thatis,frequency,pulseamplitudemodulationcontrolsignalofthemagnitudeoftheroleofthetwothesamesothatoscillationfrequencyismaintainedatwithinacertainrange,totheeffectofvoltagestability.Windingtransformercanbedividedintothreetypesingeneral,agroupinvolvedintheprimarywindingoftheoscillation,agroupistomaintaintheoscillationofthefeedbackwinding,thereisagroupoftheloadwindings.Householdappliancesusedinswitchingpowersupply,aftertheACto220Vbridgerectifier,convertedintoabout300VDC,filterintothetransformerisaddedaftertheswitchtohigh-frequencyoscillationsofthecollector,feedbackwindingbacktothebasetomaintaintheoscillationcircuit,loadsensorwindingsoftheelectricalsignal,byrectification,filtering,theDCvoltageregulatorhasbeentoprovidepowertotheload.Windingintheprovisionofelectricpowerload,butalsotakeupthecapacityofvoltagestability,thetheoryisthenacircuitvoltageoutputvoltagesamplingdevicestomonitortheoutputvoltagechanges,timelyfeedbacktoadjusttheoscillationfrequencyoscillatorcircuittoachievethevoltagestabilityThepurposeofthecircuitinordertoavoidinterference,thefeedbackvoltagetotheoscillatorcircuitwillbeisolatedoptocoupler.Mostswitcheshaveastandbypowercircuit,switchingpowersupplyinstandbymodestilloscillating,butthefrequencyofnormalworkinghoursthanlower.Someswitchingpowersupplyarecomplex,numerouscomponents,manyprotectionandcontrolcircuit,intheabsenceoftechnicalsupport,maintenanceisaheadachewiththematter.Ifacethiskindofsituationis,firstofall,Iwillfindtheswitchanditsparticipationintheexternaloscillationcircuit,itseparatedfromthecircuittoseeifitmettheconditionsforoscillation,suchasdetectionbiasandwhetheritisnormal,whetherpositivefeedbackfailure,aswellasitsownswitches,switchingpowersupplyhasverylargeprotection,afterexclusionoftheprosecutionandloadcontrolandprotectioncircuit.thecontrolcircuitwhileoutputfromthesample,withthesetstandards,thencontrolledinverter,changeitsfrequencyorpulsewidthoutputachievestability,ontheotherhand,accordingtotestdataprovidedbythecircuitbycircuitprotectionidentification,Controlcircuitfortheunitforvariousprotectionmeasures.SMPSdevelopmentsandtrendsintheUnitedStatesin1955Roje(GH.Roger)inventionoftheself-excitedoscillationpushredeemtransistorsingletransformerDCconverters,high-frequencyconversionisthebeginningofcontrolcircuit,1957UnitedStatesinvestigationtournament(JenSen)sincetheinventionofthepush-pulldoubleFlybacktransformers,1964Americanscientistsproposestoabolishthefrequencytransformerseriesswitchingpowersupplyscenario,Thispowertotherightsizeandweightofthedeclinewasafundamentalway.Tothe1969high-powersilicontransistorbecausethepressureincreasediodereverserecoverytimeshortened,andothercomponentsimprove,andfinallyturnedintoa25kHzswitchingpowersupply.Currently,switchingpowersupplytosmall,Lightvolumeandthecharacteristicsofhighefficiencyhasbeenwidelyusedinelectroniccomputer-drivenvarietyofterminalequipment,Communicationsequipmentalmostallelectronicequipment,theelectronicinformationindustryindispensabletotherapiddevelopmentofapowermode.Currentlythemarketforsaleintheswitchingpowersupplyusingbipolartransistorsmadeof100kHz.usemadeof500kHzMOSpower,thoughpractical,butitsfrequencytobefurtherenhanced.Toimprovetheswitchingfrequency,itisnecessarytoreducetheswitchingloss,andtoreducetheswitchingloss,youneedtohavehigh-speedswitchingdevices.However,theswitchingspeed,willbeaffectedbythecircuitinductanceandcapacitancediodeorstoredchargearisingfromtheimpactofthesurgeornoise.Thiswillnotonlyaffectthesurroundingelectronicequipment,butalsogreatlyreducethereliabilityofthepowersupplyitself.Amongthem,withtheswitchtopreventKai-closedbythevoltagesurge,itisR-CorL-CCompositebumpers,andthestoragechargebythediodecurrentsurgecausedbytheusemadeofamorphouscoressuchasmagneticbumper.However,thehighfrequencyof1MHzandabove,usingresonantcircuit,Switchtoenablethevoltageorcurrentthroughtheswitchwasasine,whichcouldreducetheswitchingloss,Thiscanalsocontrolthesurgeoccurred.Switchessuchasresonantmodeswitching.CurrentlysuchSMPSofveryactive,becausethismeansnosignificantincreaseswitchingspeedcantheoreticallyputswitchinglossfalltozero.andthenoiseissmall,isexpectedtobecomehigh-frequencyswitchingpowersupplyofoneofthemainways.Atpresent,manycountriesintheworldareworkingonseveraltrillionHzconverterpracticalresearch.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，廣泛應用于現(xiàn)代電子產(chǎn)品。因為開關(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)電源實質(zhì)就是一個振蕩電路，這種轉(zhuǎn)換電能的方式，不僅應用在電源電路，在其它的電路應用也很普遍，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，缺點是功率相對較小，而且會對電