外文翻译电气工程及自动化.docx

外文翻译电气工程及自动化.docx

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外文翻译电气工程及自动化

毕业论文英文翻译资料

题目：

直流开关稳压电源的保护技术

院（系）：

电气与信息工程学院

专业：

电气工程及其自动化

学生姓名：

冯启立

班级：

电气1144

学号：

1104411414

指导教师：

郭大业

何希才.新型开关电源设计与应用[M].北京:

科学出版社,2001.

DCSwitchingPowerSupplyProtectionTechnology

Abstract:

TheDCswitchingpowersupplyprotectionsystem,protectionsystemdesignprinciplesandmachineprotectionmeasures,ananalysisofswitchingpowersupplyintherangeofprotectedcharacteristicsanditsdesignmethodology,introducedanumberofpracticalprotectioncircuit.

Keywords:

switchingpowersupplyprotectioncircuitsystemdesign

A、Introduction

DCswitchingregulatorusedinthepriceofmoreexpensivehigh-powerswitchingdevices,thecontrolcircuitisalsomorecomplex,Inaddition,theloadswitchingregulatorsaregenerallyusedalargenumberofhighlyintegratedelectronicsystemsinstalleddevices.Transistorsandintegrateddevicetoleranceelectricity,lessheatshocks.SwitchingRegulatorsthereforeshouldtakeintoaccounttheprotectionofvoltageregulatorsandloadtheirownsafety.Manydifferenttypesofcircuitprotection,polarityprotection,introducedhere,theprogramprotection,over-currentprotection,over-voltageprotection,under-voltageprotectionandover-temperatureprotectioncircuit.Usuallychosentobesomecombinationofprotection,constitutesacompleteprotectionsystem.

B、Polarityprotection

DCswitchingregulatorinputisgenerallynotregulatedDCpowersupply.Operatingerrorsoraccidentsasaresultofthesituationwilltakeitswrongpolarity;switchingpowersupplywillbedamaged.Polarityprotectionpurposes,istomaketheswitchingregulatoronlywhenthecorrectpolarityisnotconnectedtoDCpowersupplyregulatortoworkat.Connectingasingledevicecanachievepowerpolarityprotection.SincethediodeDtoflowthroughswitchingregulatorinputtotalcurrent,thiscircuitappliedinalow-powerswitchingregulatormoresuitable.Powerinthelargeroccasion,whilethepolarityprotectioncircuitasaproceduretoprotectalink,savethepowerrequiredforpolarityprotectiondiodes,powerconsumptionwillbereduced.Inordertoeasytooperate,makeiteasiertoidentifythecorrectpolarityornot,collectthenextlight.

C、Procedurestoprotect

Switchingpowersupplycircuitisrathercomplicated,basicallycanbedividedintolow-powerandhigh-powerpartofthecontrolpartoftheswitch.Switchisahigh-powertransistors,fortheprotectionofthetransistorswitchisturnedonoroffpowersafety,wemustfirstmodulator,amplifierandotherlow-powercontrolcircuit.Tothisend,theboottoensurethecorrectprocedures.SwitchingRegulatorsgenerallytaketheinputofasmallinductor,theinputfiltercapacitor.Momentintheboot,filtercapacitorwillflowalotofsurgecurrent,thesurgecurrentcanbeseveraltimesmorethanthenormalinputcurrent.Suchalargesurgecurrentmaycontactthegeneralpowerswitchorrelaycontactmelting,andtheinputfuse.Inaddition,thecapacitorsurgecurrentwilldamagetoshortenthelifespanofprematuredamage.Tothisend,thebootshouldbeaccesstoacurrentlimitingresistor,throughthecurrentlimitingresistortocapacitorcharging.Inordernottomakethecurrentlimitingresistorexcessivepowerconsumption,thusaffectingthenormalswitchingregulator,andthetransientprocessinthebootafterashortperiodthenautomaticallyrelaysittoDCpowersupplydirectlytotheswitchingregulatorpowersupply.Thiscircuitswitchingregulatorcalleda"softstart"circuit.

Switchingregulatorcontrolcircuitofthelogiccomponentsrequiredorop-ampauxiliarypowersupply.Tothisend,theauxiliarypowersupplymustbeintheswitchcircuit.Thiscontrolcircuitcanbeusedtoensuretheboot.Normalbootprocessis:

toidentifythepolarityofinputpower,voltageprotectionprocedures→boot→auxiliarypowersupplycircuitandthroughcurrentlimitingresistorRoftheswitchingregulatorinputcapacitorC→chargemodulationswitchingregulatorcircuit,→short-circuitcurrentlimitingresistorstabilityswitchingregulator.

Intheswitchingregulator,themachinesjustbecausetheoutputcapacitance,andchargetotheratedoutputvoltagevalueoftheneedforacertainperiodoftime.Duringthistime,samplingtheoutputamplifierwithlowinputvoltagesampling,closed-loopregulationcharacteristicsofthesystemwillforcetheswitchingofthetransistorconductiontimelengthened,sothatswitchingtransistorduringthisperiodwilltendtocontinuousconduction,andeasilydamaged.Tothisend,therequirementsofthisparagraphintheboottime,theswitchtoswitchtheoutputmodulationcircuittransistorbasedrivesignalofthepulsewidthmodulation,canguaranteetheswitchingtransistorbythecut-offswitchesarebecomingmoreandmorenormalstate,thereforetheprotectionofthesettingupofaboottotieinwiththesoftstart.

D、Over-currentprotection

Whentheloadshort-circuit,overloadcontrolcircuitfailureorunforeseencircumstances,suchaswouldcausetheflowofswitchingvoltageregulatortransistorcurrentistoolarge,sothatincreasedpowertubes,fever,ifthereisnoover-currentprotectiondevice,highpowerswitchingtransistormaybedamaged.Therefore,theswitchingregulatorintheover-currentprotectioniscommonlyused.Themosteconomicalwayistousesimplefuse.Asaresultoftheheatcapacityofsmalltransistors,generalfuseprotectioningeneralcannotplayaroleintherapidfusecommonfuse.Thismethodhastheadvantageoftheprotectionofvulnerable,butitneedstoswitchtransistorinaccordancewithspecificsecurityrequirementsoftheworkareatoselectthefusespecifications.Thisdisadvantageisover-currentprotectionmeasuresbroughtaboutbytheinconvenienceoffrequentreplacementoffuses.

Linearvoltageregulatorcommonlyusedintheprotectionandcurrentlimitingtoprotectthecut-offintheswitchingregulatorcanbeapplied.However,accordingtothecharacteristicsofswitchingregulators,theprotectioncircuitcannotdirectlycontroltheoutputtransistorswitches,andovercurrentprotectionmustbeconvertedtopulseoutputcommandstocontrolthemodulatortoprotectthetransistorswitch.Inordertoachieveover-currentprotectionaregenerallyrequiredsamplingresistorinseriesinthecircuit,thiswillaffecttheefficiencyofpowersupply,somoreforlow-powerswitchingregulatorofoccasions.Inthehigh-powerswitchingpowersupply,bytakingintoaccountthepowerconsumptionshouldbeavoidedasfaraspossibleaccesstothesamplingresistor.Therefore,therewillusuallybeconvertedtoover-currentprotection,andunder-voltageprotection.

E、Over-voltageprotection

Switchingregulator'sinputover-voltageprotection,includingover-voltageprotectionandoutputover-voltageprotection.SwitchingregulatorisnotusedinDCpowersupplyvoltageregulatorandrectifier,suchasbatteryvoltage,iftoohigh,soswitchingregulatorisnotworkingproperly,orevendamagetointernaldevices,therefore,itisnecessarytousetheinputover-voltageprotectioncircuit.Usingtransistorsandrelaysprotectioncircuit.

Inthecircuit,whentheinputDCpowersupplyvoltagehigherthanthevoltageregulatordiodebreakdownvoltagevalue,thebreakdownvoltageregulatortube,acurrentflowingthroughresistorR,sothatVturn-ontransistor,relay,normallyclosedcontactoffopen,cutofftheinput.VoltageregulatorvoltageregulatorwhichcontrolsthevalueofVs.=Earwax-UBE.Thepolarityofinputpowerwiththeinputprotectioncircuitcanbecombinedwithover-voltageprotection,polarityprotectionconstituteadifferentialcircuitandovervoltageprotection.

Outputover-voltageprotectionswitchingpowersupplyisessential.Inparticular,forthe5Voutputoftheswitchingregulator,itisalotofloadonahighlevelofintegrationofthelogicdevice.Ifatwork,switchingregulatorsuddendamagetotheswitchtransistor,theoutputpotentialmaybeincreasedimmediatelytotheimportationofnon-regulatedDCpowersupplyvoltagevalue,causinggreatlossinstantaneous.Commonlyusedmethodisshort-circuitprotectionthirsted.Thesimplestover-voltageprotectioncircuit.Whentheoutputvoltageistoohigh,theregulatortubebreakdowntriggeredthirstierturn-on,theoutputshort-circuit,resultinginover-currentthroughthefuseorcircuitprotectivedevicetocutofftheinputtoprotecttheload.Thiscircuitisequivalenttotheresponsetimeoftheopeningtimeofthirstierisabout5~10μs.Thedisadvantageisthatitsactionisfixedvoltage,temperaturecoefficient,andactionpointsofinstability.Inaddition,thereisavoltageregulatorcontrolparametersofthediscrete,modelover-voltagestart-upthesamebuthasdifferentvalues,difficulttodebug.Escasuddenincreaseinoutputvoltage,transistorsV1,V2conduction,thethrusterconduction.ReferencevoltageVs.bytype.

F、Under-voltageprotection

OutputvoltagebelowthevaluetoreflecttheinputDCpowersupply,switchingregulatoroutputloadinternalorunusualoccurrence.InputDCpowersupplyvoltagedropsbelowthespecifiedvaluewouldresultinswitchingregulatoroutputvoltagedrops,theinputcurrentincreases,notonlyendangertheswitchingtransistor,butalsoendangertheinputpower.Therefore,inordertosetupduetovoltageprotection.Duetosimplevoltageprotection.

Whennovoltageregulatorinputnormal,ZDbreakdownvoltageregulatortube,transistorsVconduction,therelayaction,contactpull-in,power-switchingregulator.Whentheinputbelowtheminimumallowablevoltagevalue,theregulatortubeZDbarrier,Vcut-off,contactKai-hop,switchingregulatorcannotwork.Internalswitch