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外文翻译--直流开关稳压电源的保护技术.doc

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外文翻译--直流开关稳压电源的保护技术.doc

2009届电气工程与自动化专业毕业设计外文翻译1TranslatedfromXiongFusheng,DCSwitchingPowerSupplyProtectionTechnology,GuangzhouTheWorldofPowerSupplyP,2002.2.DCSwitchingPowerSupplyProtectionTechnologyAbstractTheDCswitchingpowersupplyprotectionsystem,protectionsystemdesignprinciplesandmachineprotectionmeasures,ananalysisofswitchingpowersupplyintherangeofprotectedcharacteristicsanditsdesignmethodology,introducedanumberofpracticalprotectioncircuit.Keywordsswitchingpowersupplyprotectioncircuitsystemdesign1、IntroductionDCswitchingregulatorusedinthepriceofmoreexpensivehighpowerswitchingdevices,thecontrolcircuitisalsomorecomplex,Inaddition,theloadswitchingregulatorsaregenerallyusedalargenumberofhighlyintegratedelectronicsystemsinstalleddevices.Transistorsandintegrateddevicetoleranceelectricity,lessheatshocks.SwitchingRegulatorsthereforeshouldtakeintoaccounttheprotectionofvoltageregulatorsandloadtheirownsafety.Manydifferenttypesofcircuitprotection,polarityprotection,introducedhere,theprogramprotection,overcurrentprotection,overvoltageprotection,undervoltageprotectionandovertemperatureprotectioncircuit.Usuallychosentobesomecombinationofprotection,constitutesacompleteprotectionsystem.2、polarityprotectionDCswitchingregulatorinputaregenerallynotregulatedDCpowersupply.Operatingerrorsoraccidentsasaresultofthesituationwilltakeitswrongpolarity,switchingpowersupplywillbedamaged.Polarityprotectionpurposes,istomaketheswitchingregulatoronlywhenthecorrectpolarityisnotconnectedtoDCpowersupplyregulatortoworkat.Connectingasingledevicecanachievepowerpolarityprotection.SincethediodeDtoflowthroughswitchingregulatorinputtotalcurrent,thiscircuitappliedinalowpowerswitchingregulatormoresuitable.Powerinthelargeroccasion,whilethepolarityprotectioncircuitasaproceduretoprotectalink,savethepowerrequiredforpolarityprotectiondiodes,powerconsumptionwillbereduced.Inordertoeasytooperate,makeiteasiertoidentifythecorrectpolarityornot,collectthenextlight.仇有年宽输入电压高频开关电源的设计23、procedurestoprotectSwitchingpowersupplycircuitisrathercomplicated,basicallycanbedividedintolowpowerandhighpowerpartofthecontrolpartoftheswitch.Switchisahighpowertransistors,fortheprotectionofthetransistorswitchisturnedonoroffpowersafety,wemustfirstmodulator,amplifierandotherlowpowercontrolcircuit.Tothisend,theboottoensurethecorrectprocedures.SwitchingRegulatorsgenerallytaketheinputofasmallinductor,theinputfiltercapacitor.Momentintheboot,filtercapacitorwillflowalotofsurgecurrent,thesurgecurrentcanbeseveraltimesmorethanthenormalinputcurrent.Suchalargesurgecurrentmaycontactthegeneralpowerswitchorrelaycontactmelting,andtheinputfusefuse.Inaddition,thecapacitorsurgecurrentwilldamagetoshortenthelifespanofprematuredamage.Tothisend,thebootshouldbeaccesstoacurrentlimitingresistor,throughthecurrentlimitingresistortocapacitorcharging.Inordernottomakethecurrentlimitingresistorexcessivepowerconsumption,thusaffectingthenormalswitchingregulator,andthetransientprocessinthebootafterashortperiodthenautomaticallyrelaysittoDCpowersupplydirectlytotheswitchingregulatorpowersupply.Thiscircuitswitchingregulatorcalledasoftstartcircuit.Switchingregulatorcontrolcircuitofthelogiccomponentsrequiredoropampauxiliarypowersupply.Tothisend,theauxiliarypowersupplymustbeintheswitchcircuit.Thiscontrolcircuitcanbeusedtoensuretheboot.Normalbootprocessistoidentifythepolarityofinputpower,voltageprotectionprocedures→boot→auxiliarypowersupplycircuitandthroughcurrentlimitingresistorRoftheswitchingregulatorinputcapacitorC→chargemodulationswitchingregulatorcircuit,→shortcircuitcurrentlimitingresistorstabilityswitchingregulator.Intheswitchingregulator,themachinesjustbecausetheoutputcapacitance,andchargetotheratedoutputvoltagevalueoftheneedforacertainperiodoftime.Duringthistime,samplingtheoutputamplifierwithlowinputvoltagesampling,closedloopregulationcharacteristicsofthesystemwillforcetheswitchingofthetransistorconductiontimelengthened,sothatswitchingtransistorduringthisperiodwilltendtocontinuousconduction,andeasilydamaged.Tothisend,therequirementsofthisparagraphintheboottime,theswitchtoswitchtheoutputmodulationcircuittransistorbasedrivesignalofthepulsewidthmodulation,canguaranteetheswitchingtransistorbythecutoffswitchesarebecoming2009届电气工程与自动化专业毕业设计外文翻译3moreandmorenormalstate,thereforetheprotectionofthesettingupofaboottotieinwiththesoftstart.4、overcurrentprotectionWhentheloadshortcircuit,overloadcontrolcircuitfailureorunforeseencircumstances,suchaswouldcausetheflowofswitchingvoltageregulatortransistorcurrentistoolarge,sothatincreasedpowertubes,fever,ifthereisnoovercurrentprotectiondevice,highpowerswitchingtransistormaybedamaged.Therefore,theswitchingregulatorintheovercurrentprotectioniscommonlyused.Themosteconomicalwayistousesimplefuse.Asaresultoftheheatcapacityofsmalltransistors,generalfuseprotectioningeneralcannotplayaroleintherapidfusecommonfuse.Thismethodhastheadvantageoftheprotectionofvulnerable,butitneedstoswitchtransistorinaccordancewithspecificsecurityrequirementsoftheworkareatoselectthefusespecifications.Thisdisadvantageisovercurrentprotectionmeasuresbroughtaboutbytheinconvenienceoffrequentreplacementoffuses.Linearvoltageregulatorcommonlyusedintheprotectionandcurrentlimitingtoprotectthecutoffintheswitchingregulatorcanbeapplied.However,accordingtothecharacteristicsofswitchingregulators,theprotectioncircuitcannotdirectlycontroltheoutputtransistorswitches,andovercurrentprotectionmustbeconvertedtopulseoutputcommandstocontrolthemodulatortoprotectthetransistorswitch.Inordertoachieveovercurrentprotectionaregenerallyrequiredsamplingresistorinseriesinthecircuit,thiswillaffecttheefficiencyofpowersupply,somoreforlowpowerswitchingregulatorofoccasions.Inthehighpowerswitchingpowersupply,bytakingintoaccountthepowerconsumptionshouldbeavoidedasfaraspossibleaccesstothesamplingresistor.Therefore,therewillusuallybeconvertedtoovercurrentprotection,andundervoltageprotection.5、overvoltageprotectionSwitchingregulatorsinputovervoltageprotection,includingovervoltageprotectionandoutputovervoltageprotection.SwitchingregulatorisnotusedinDCpowersupplyvoltageregulatorandrectifier,suchasbatteryvoltage,iftoohigh,soswitchingregulatorisnotworkingproperly,orevendamagetointernaldevices,therefore,itisnecessarytousetheinputovervoltageprotectioncircuit.Usingtransistorsandrelaysprotectioncircuit.Inthecircuit,whentheinputDCpowersupplyvoltagehigherthanthevoltageregulatordiodebreakdownvoltagevalue,thebreakdownvoltageregulatortube,acurrent仇有年宽输入电压高频开关电源的设计4flowingthroughresistorR,sothatVturnontransistor,relay,normallyclosedcontactoffopen,cutofftheinput.VoltageregulatorvoltageregulatorwhichcontrolsthevalueofVzESrmaxUBE.Thepolarityofinputpowerwiththeinputprotectioncircuitcanbecombinedwithovervoltageprotection,polarityprotectionconstituteadifferentialcircuitandovervoltageprotection.Outputovervoltageprotectionswitchingpowersupplyisessential.Inparticular,forthe5Voutputoftheswitchingregulator,itisalotofloadonahighlevelofintegrationofthelogicdevice.Ifatwork,switchingregulatorsuddendamagetotheswitchtransistor,theoutputpotentialmaybeincreasedimmediatelytotheimportationofnonregulatedDCpowersupplyvoltagevalue,causinggreatlossinstantaneous.Commonlyusedmethodisshortcircuitprotectionthyristor.Thesimplestovervoltageprotectioncircuit.Whentheoutputvoltageistoohigh,theregulatortubebreakdowntriggeredthyristorturnon,theoutputshortcircuit,resultinginovercurrentthroughthefuseorcircuitprotectivedevicetocutofftheinputtoprotecttheload.Thiscircuitisequivalenttotheresponsetimeoftheopeningtimeofthyristorisabout510μs.Thedisadvantageisthatitsactionisfixedvoltage,temperaturecoefficient,andactionpointsofinstability.Inaddition,thereisavoltageregulatorcontrolparametersofthediscrete,modelovervoltagestartupthesamebuthasdifferentvalues,difficulttodebug.Escasuddenincreaseinoutputvoltage,transistorsV1,V2conduction,thethyristorconduction.ReferencevoltageVzbytype.6、undervoltageprotectionOutputvoltagebelowthevaluetoreflecttheinputDCpowersupply,switchingregulatoroutputloadinternalorunusualoccurrence.InputDCpowersupplyvoltagedropsbelowthespecifiedvaluewouldresultinswitchingregulatoroutputvoltagedrops,theinputcurrentincreases,notonlyendangertheswitchingtransistor,butalsoendangertheinputpower.Therefore,inordertosetupduetovoltageprotection.Duetosimplevoltageprotection.Whennovoltageregulatorinputnormal,ZDbreakdownvoltageregulatortube,transistorsVconduction,therelayaction,contactpullin,powerswitchingregulator.Whentheinputbelowtheminimumallowablevoltagevalue,theregulatortubeZDbarrier,Vcutoff,contactKaihop,switchingregulatorcannotwork.Internalswitchingregulator,asthecontrolswitchtransistorcircuitdisordersorfailurewilldecreasetheoutputvoltageloadshortcircuitoutputvoltagewillalsodecline.

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