毕业英语材料翻译.docx
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毕业英语材料翻译.docx
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毕业英语材料翻译
DCSwitchingPowerSupplyProtectionTechnology
Abstract:
TheDCswitchingpowersupplyprotectionsystem,protectionsystemdesignprinciplesandmachineprotectionmeasures,ananalysisofswitchingpowersupplyintherangeofprotectedcharacteristicsanditsdesignmethodology,introducedanumberofpracticalprotectioncircuit.
Keywords:
switchingpowersupplyprotectioncircuitsystemdesign
1Introduction
DCswitchingregulatorusedinthepriceofmoreexpensivehigh-powerswitchingdevices,thecontrolcircuitisalsomorecomplex,Inaddition,theloadswitchingregulatorsaregenerallyusedalargenumberofhighlyintegratedelectronicsystemsinstalleddevices.Transistorsandintegrateddevicetoleranceelectricity,lessheatshocks.SwitchingRegulatorsthereforeshouldtakeintoaccounttheprotectionofvoltageregulatorsandloadtheirownsafety.Manydifferenttypesofcircuitprotection,polarityprotection,introducedhere,theprogramprotection,over-currentprotection,over-voltageprotection,under-voltageprotectionandover-temperatureprotectioncircuit.Usuallychosentobesomecombinationofprotection,constitutesacompleteprotectionsystem.
2Polarityprotection
DCswitchingregulatorinputaregenerallynotregulatedDCpowersupply.Operatingerrorsoraccidentsasaresultofthesituationwilltakeitswrongpolarity.switchingpowersupplywillbedamaged.Polarityprotectionpurposes,istomaketheswitchingregulatoronlywhenthecorrectpolarityisnotconnectedtoDCpowersupplyregulatortoworkatConnectingasingledevicecanachievepowerpolarityprotection.SincethediodeDtoflowthroughswitchingregulatorinputtotalcurrent,thiscircuitappliedinalow-powerswitchingregulatormoresuitable.Powerinthelargeroccasion,whilethepolarityprotectioncircuitasaproceduretoprotectalink,savethepowerrequiredforpolarityprotectiondiodes,powerconsumptionwillbereduced.Inordertoeasytooperate,makeiteasiertoidentifythecorrectpolarityornot,collectthenextlight.
3Procedurestoprotect
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.
4Over-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.
5Over-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.VoltageregulatorvoltageregulatorwhichcontrolsthevalueofVz=ESrmax-UBE.Thepolarityofinputpowerwiththeinputprotectioncircuitcanbecombinedwithover-voltageprotection,polarityprotectionconstituteadifferentialcircuitandovervoltageprotection.
Outputover-voltageprotectionswitchingpowersupplyisessential.Inparticular,forthe5Voutputoftheswitchingregulator,itisalotofloadonahighlevelofintegrationofthelogicdevice.Ifatwork,switchingregulatorsuddendamagetotheswitchtransistor,theoutputpotentialmaybeincreasedimmediatelytotheimportationofnon-regulatedDCpowersupplyvoltagevalue,causinggreatlossinstantaneous.Commonlyusedmethodisshort-circuitprotectionthyristor.Thesimplestover-voltageprotectioncircuit.Whentheoutputvoltageistoohigh,theregulatortubebreakdowntriggeredthyristorturn-on,theoutputshort-circuit,resultinginover-currentthroughthefuseorcircuitprotectivedevicetocutofftheinputtoprotecttheload.Thiscircuitisequivalenttotheresponsetimeoftheopeningtimeofthyristorisabout5~10μs.Thedisadvantageisthatitsactionisfixedvoltage,temperaturecoefficient,andactionpointsofinstability.Inaddition,thereisavoltageregulatorcontrolparametersofthediscrete,modelover-voltagestart-upthesamebuthasdifferentvalues,difficulttodebug.Escasuddenincreaseinoutputvoltage,transistorsV1,V2conduction,thethyristorconduction.ReferencevoltageVzbytype.
6Under-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.Internalswitchingregulator,asthecontrolswitchtransistorcircuitdisordersorfailurewilldecreasetheoutputvoltage;loadshort-circuitoutputvoltagewillalsodecline.
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