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1、 DCSwitchingPowerSupplyProtectionTechnologyAbstract:TheDCswitchingpowersupplyprotectionsystem,protectionsystemdesignprinciplesandmachineprotectionmeasures,ananalysisofswitchingpowersupplyintherangeofprotectedcharacteristicsanditsdesignmethodology,introducedanumberofpracticalprotectioncircuit.Keyword
2、s:switchingpowersupplyprotectioncircuitsystemdesignA、Introduction. DC switchingregulatorusedinthepriceofmoreexpensivehigh-powerswitchingdevices,thecontrolcircuitisalsomorecomplex,Inaddition,theloadswitchingregulatorsaregenerallyusedalargenumberofhighlyintegratedelectronicsystemsinstalleddevices.Tran
3、sistorsandintegrateddevicetoleranceelectricity,lessheatshocks.SwitchingRegulatorsthereforeshouldtakeintoaccounttheprotectionofvoltageregulatorsandloadtheirownsafety.Manydifferenttypesofcircuitprotection,polarityprotection,introducedhere,theprogramprotection,over-currentprotection,over-voltageprotect
4、ion,under-voltageprotectionandover-temperatureprotectioncircuit.Usuallychosentobesomecombinationofprotection,constitutesacompleteprotectionsystem.B、PolarityprotectionDCswitchingregulatorinputisgenerallynotregulatedDCpowersupply.Operatingerrorsoraccidentsasaresultofthesituationwilltakeitswrongpolarit
5、y;switchingpowersupplywillbedamaged.Polarityprotectionpurposes,istomaketheswitchingregulatoronlywhenthecorrectpolarityisnotconnectedtoDCpowersupplyregulatortoworkat.Connectingasingledevicecanachievepowerpolarityprotection.SincethediodeDtoflowthroughswitchingregulatorinputtotalcurrent,thiscircuitappl
6、iedinalow-powerswitchingregulatormoresuitable.Powerinthelargeroccasion,whilethepolarityprotectioncircuitasaproceduretoprotectalink,savethepowerrequiredforpolarityprotectiondiodes,powerconsumptionwillbereduced.Inordertoeasytooperate,makeiteasiertoidentifythecorrectpolarityornot,collectthenextlight.C、
7、ProcedurestoprotectSwitchingpowersupplycircuitisrathercomplicated,basicallycanbedividedintolow-powerandhigh-powerpartofthecontrolpartoftheswitch.Switchisahigh-powertransistors,fortheprotectionofthetransistorswitchisturnedonoroffpowersafety,wemustfirstmodulator,amplifierandotherlow-powercontrolcircui
8、t.Tothisend,theboottoensurethecorrectprocedures.SwitchingRegulatorsgenerallytaketheinputofasmallinductor,theinputfiltercapacitor.Momentintheboot,filtercapacitorwillflowalotofsurgecurrent,thesurgecurrentcanbeseveraltimesmorethanthenormalinputcurrent.Suchalargesurgecurrentmaycontactthegeneralpowerswit
9、chorrelaycontactmelting,andtheinputfuse.Inaddition,thecapacitorsurgecurrentwilldamagetoshortenthelifespanofprematuredamage.Tothisend,thebootshouldbeaccesstoacurrentlimitingresistor,throughthecurrentlimitingresistortocapacitorcharging.Inordernottomakethecurrentlimitingresistorexcessivepowerconsumptio
10、n,thusaffectingthenormalswitchingregulator,andthetransientprocessinthebootafterashortperiodthenautomaticallyrelaysittoDCpowersupplydirectlytotheswitchingregulatorpowersupply.Thiscircuitswitchingregulatorcalledasoftstartcircuit. Switchingregulatorcontrolcircuitofthelogiccomponentsrequiredorop-ampauxi
11、liarypowersupply.Tothisend,theauxiliarypowersupplymustbeintheswitchcircuit.Thiscontrolcircuitcanbeusedtoensuretheboot.Normalbootprocessis:toidentifythepolarityofinputpower,voltageprotectionproceduresbootauxiliarypowersupplycircuitandthroughcurrentlimitingresistorRoftheswitchingregulatorinputcapacito
12、rC chargemodulationswitchingregulatorcircuit,short-circuitcurrentlimitingresistorstabilityswitchingregulator. Intheswitchingregulator,themachinesjustbecausetheoutputcapacitance,andchargetotheratedoutputvoltagevalueoftheneedforacertainperiodoftime.Duringthistime,samplingtheoutputamplifierwithlowinput
13、voltagesampling,closed-loopregulationcharacteristicsofthesystemwillforcetheswitchingofthetransistorconductiontimelengthened,sothatswitchingtransistorduringthisperiodwilltendtocontinuousconduction,andeasilydamaged.Tothisend,therequirementsofthisparagraphintheboottime,theswitchtoswitchtheoutputmodulat
14、ioncircuittransistorbasedrivesignalofthepulsewidthmodulation,canguaranteetheswitchingtransistorbythecut-offswitchesarebecomingmoreandmorenormalstate,thereforetheprotectionofthesettingupofaboottotieinwiththesoftstart.D、Over-currentprotectionWhentheloadshort-circuit,overloadcontrolcircuitfailureorunfo
15、reseencircumstances,suchaswouldcausetheflowofswitchingvoltageregulatortransistorcurrentistoolarge,sothatincreasedpowertubes,fever,ifthereisnoover-currentprotectiondevice,highpowerswitchingtransistormaybedamaged.Therefore,theswitchingregulatorintheover-currentprotectioniscommonlyused.Themosteconomica
16、lwayistousesimplefuse.Asaresultoftheheatcapacityofsmalltransistors,generalfuseprotectioningeneralcannotplayaroleintherapidfusecommonfuse.Thismethodhastheadvantageoftheprotectionofvulnerable,butitneedstoswitchtransistorinaccordancewithspecificsecurityrequirementsoftheworkareatoselectthefusespecificat
17、ions.Thisdisadvantageisover-currentprotectionmeasuresbroughtaboutbytheinconvenienceoffrequentreplacementoffuses. Linearvoltageregulatorcommonlyusedintheprotectionandcurrentlimitingtoprotectthecut-offintheswitchingregulatorcanbeapplied.However,accordingtothecharacteristicsofswitchingregulators,thepro
18、tectioncircuitcannotdirectlycontroltheoutputtransistorswitches,andovercurrentprotectionmustbeconvertedtopulseoutputcommandstocontrolthemodulatortoprotectthetransistorswitch.Inordertoachieveover-currentprotectionaregenerallyrequiredsamplingresistorinseriesinthecircuit,thiswillaffecttheefficiencyofpow
19、ersupply,somoreforlow-powerswitchingregulatorofoccasions.Inthehigh-powerswitchingpowersupply,bytakingintoaccountthepowerconsumptionshouldbeavoidedasfaraspossibleaccesstothesamplingresistor.Therefore,therewillusuallybeconvertedtoover-currentprotection,andunder-voltageprotection.F、Under-voltageprotect
20、ionOutputvoltagebelowthevaluetoreflecttheinputDCpowersupply,switchingregulatoroutputloadinternalorunusualoccurrence.InputDCpowersupplyvoltagedropsbelowthespecifiedvaluewouldresultinswitchingregulatoroutputvoltagedrops,theinputcurrentincreases,notonlyendangertheswitchingtransistor,butalsoendangerthei
21、nputpower.Therefore,inordertosetupduetovoltageprotection.Duetosimplevoltageprotection. Whennovoltageregulatorinputnormal,ZDbreakdownvoltageregulatortube,transistorsVconduction,therelayaction,contactpull-in,power-switchingregulator.Whentheinputbelowtheminimumallowablevoltagevalue,theregulatortubeZDba
22、rrier,Vcut-off,contactKai-hop, switchingregulatorcannotwork.Internalswitchingregulator,asthecontrolswitchtransistorcircuitdisordersorfailurewilldecreasetheoutputvoltage;loadshort-circuitoutputvoltagewillalsodecline. Especiallyinthereversed-phasestep-uporstep-upswitchingregulatorDCvoltageoftheprotect
23、ionduetoover-currentprotectionwithcloselyrelatedandthereforemoreimportant.ImplementationofSwitchingRegulatorsintheterminationoftheoutputvoltagecomparators. Normally,thereisnocomparatoroutput,oncethevoltagedropsbelowtheallowablevalueinthecomparatorontheflip,drivealarmcircuit;alsofedbacktotheswitching
24、regulatorcontrolcircuit,sothatswitchingtransistorcut-offorcutofftheinputpower.G、Over-temperatureprotectionSwitchingregulatorandthehighlevelofintegrationoflight-weightsmallvolume,withitsunitvolumegreatlyincreasedthepowerdensity,powersupplycomponentstoitsworkwithintherequirementsoftheambienttemperatur
25、eisalsoacorrespondingincrease.Otherwise,thecircuitperformancewilldeteriorateprematurecomponentfailure.Therefore,inhigh-powerswitchingregulatorshouldbesetupover-temperatureprotection. Relaysusedtodetectthetemperatureinsidethepowersupplytemperature,whentheinternallygeneratedpowersupplyoverheating,thet
26、emperatureoftherelayontheaction,sothatwholecircuitinawarningalarm,andtherealizationofthepowersupplyover-temperatureprotection.Temperaturerelaycanbeplacedinthevicinityoftheswitchingtransistor,thegeneralhigh-powertubeshelltoallowthemaximumtemperatureis75,adjustthetemperaturesettingto60.Whentheshellaft
27、erthetemperatureexceedstheallowablevaluetocutoffelectricalrelayontheswitchprotection.Semiconductorswitchingdevicethermalhotthirstier,intheover-temperatureprotection,playedanimportantrole.Itcanbeusedas directedcircuittemperature.Underthecontrolofp-hot-gatethirstier(TT102)characteristics,byRTvaluetode
28、terminethetemperatureofthedeviceturn-on,RTgreaterthetemperaturethelowertheturn-on.Whenplacednearthepowerswitchingtransistororpowerdevice,itwillbeabletoplaytheroleoftemperatureinstructions.Whenthepowercontrolthetemperatureoftheshellortheinternaldevicetemperatureexceedstheallowedvalue,theheatconductio
29、nthirstieron,sothatLEDwarninglight.Iftheoptcouplerwith,wouldenablethewholecircuitalarmactiontoprotecttheswitchingregulator.Itcanalsobeusedasapowertransistorastheover-temperatureprotection,crystalswitchthebasecurrentbyn-typegatecontrolthirstierTT201thermalbypass,cut-offswitchtocutoffthecollectorcurre
30、nttopreventoverheating.H、ThefuturedevelopmentofrelayprotectionProtectiontechnologytofuturetrendsiscomputerized,network,intelligent,protectionandcontrol,measurementanddatacommunicationsintegrationdevelopment.1) ComputerizedAlongwiththerapiddevelopmentofcomputerhardware,microcomputerprotectionanddevel
31、opmentinhardware.Formernorthelectricityinstituteofcomputerlineprotectionhardwarehasexperiencedthreedevelopmentstages:fromeightsingleCPUstructureofthemicrocomputerrelayprotection,lessthan5yearstimetodevelopmoreCPUstructure,andtodevelopthelargedontbusmodule,performancegreatlyimprovemodulestructure,wid
32、elyused.Huazhonguniversityofscienceandtechnologydevelopmentofmicrocomputerprotectionfrom8bitsCPU,isthecorepartinpolymerizing-kettledevelopmentbasedon32-bitmicrocomputerprotection. Nanjinginstituteofelectricalautomationbegana16-bitCPUisdevelopedonthebasisofcomputerlineprotection,hasbeenwidespreadin t
33、hestudy,alsoprotectthehardwaresystem32bits.Thedevelopmentofsoutheastuniversitycomputerhardwareandequipmenttoprotectandimprovethroughalot.Tianjinuniversityisastartwithmorethan16bitsCPUdevelopedonthebasisofcomputerlineprotection,whichbeganin1988study32-bitdigitalsignalprocessor(DSP)fortheprotectionand
34、control,measuringdevices,microcomputerintegratedwithZhuhaijinelectricalautomationequipmentcompanydevelopedintoafullyfunctional32-bitbigmodules,amoduleisasmallcomputer.Using32-bitmicrocomputerchipisnotonlybecausetheaccuracyandprecisionoftheA/Dconverterbytheresolutionlimit,morethan16whenconvertingspee
35、dandcostisunacceptable,Moreimportantisthe32-bitmicrocomputerchipwithhighintegrity,highfrequencyandcomputingspeedandlargespace,richaddressingthecommandsystemandmoreinputoutput.TheCPUregisters,databus,theaddressbusare32-bitmemorymanagementfunction,andmemoryprotectionfunctionandtasks,andtheconversionfu
36、nctionwillCache(Cache)andfloating-pointcomponentsareintegratedintheCPU.2） NetworkPowersystemofmicrocomputerprotectionrequirement,besidesimprovingthebasicfunctionofprotection,alsoshouldhavethecapacityofthefaultinformationanddatastoragespace,long-termfastdataprocessingfunction,strongcommunicationabili
37、ty,andotherprotectionandcontroldevicesandthewholesystembysharingnetworkdispatchingdata,informationandnetworkresources,theabilitytoprograminahigh-levellanguage,etc.ThisrequiresmicrocomputerprotectiondeviceisequivalenttoaPC.Intheearlydevelopmentofcomputertoprotect,oncethoughttouseasmallcomputerfinishr
38、elayprotectiondevice.Duetothelargesize,thenminicomputershighcostandreliabilityofthisideaisnotreality.Now,withmicroprocessor-basedprotectionfunctionofsimilarsize,speed,work-managingmachinegreatlyexceedthestoragecapacityof 9 minicomputer,therefore,makeuseoftherelayprotectionsetspolymerizing-kettletime
39、isripe,thisisthedevelopmentdirectionofthemicrocomputerrelayprotection. TianjinUniversityhasdevelopedwithmicroprocessor-basedprotectiondevicewithanidenticalstructurereformpolymerizing-kettleofrelayprotectiondevice.Thisdevicehasseveraladvantages:(1)486PCmachinecanmeetallthefunctionsofthecurrentandfutu
40、redemandsofmicrocomputerprotectionfunction.(2)dimensionandstructureandthecurrentprotectiondevice,exquisiteworkmanship,shockproof,preventoverheating,preventingelectromagneticinterferenceabilityisstrong,canruninverybadworkingenvironment,costcanbeaccepted.(3)usingSTDbusorPCbus,hardwaremodular,fordiffer
41、entprotectioncanbearbitrarilychoosedifferentmodules,flexibleconfiguration,easyextension. Themicrocomputerrelayprotectiondevice,computerizedisirreversibletrend.Buthowtobettersatisfypowersystem,howtofurtherimprovethereliabilityoftherelayprotection,andhowtoobtainmoreeconomicbenefitandsocialbenefit,stil
42、lmustspecificallyin-depthresearch.820networks Thecomputernetworkinformationanddatacommunicationtoolhasbecomethemainstayoftheinformationage,makehumanproductiontechnologyandsociallifeofthefundamentalchangeshavetakenplace.Itisdeeplyaffectallindustries,aswellasvariousindustryprovidespowerfulmeansofcommunication.Sofar,inadditiontothedifferentialprotectiondisoperationandprotectionoftherelayprotection