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HIGH

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HIGH

    HIGH

CHnESEJOURNALOFMECHANICALENGINEERING

    ;v01.21,No.6,2008?63?

    ;DOI:10.39011CJME200806.063,availableonlineatwww.cjmenet.corn;www.cjmenet.corn.cn

    ;QIANGJiaxi

    ;AOGuoqiang

    ;,rANGLin

    ;nstituteofAutomobileElectronic

    ;Technology

    ;ShanghaiJiaotongUniversity,

    ;Shanghai200240,China

    ;OINTRoDUCTIoN

    ;HIGHVOrAGESAFETYMANAGE.

    ;MENTSYSTEMOFELECTRIC

    ;VEHICLE

    ;Abstract:Inordertoimprovethedriv

    I1ityandenergYemciencyofelectricvehicle(EV),moreand

    ;morebatteriesareconnectedinserieswitl1highvoltagewhichmakesitnecessarytomonitorthe

    ;electricparametersofhighvoltagesystem(HVS)toensurethehighvoltagesafety.Ahighvoltage

    ;safetymanagementsystemisdevelopedtosolvethiscriticalissue.Severa1keyelectricparameters

    ;includingprecharge,contactresistance,insulationresistanceandremainingcapacityaremonitored

    ;andanalyzedbasedon

    epresentedequivalentmodels.Anelectronicunitcalledhighvoltagesafety ;controllerisdeveloped.Bythehelpofhardware.in.1oopsystem.theequivalentmodelsintegratedin

    ;thehighvoltagesafctycontrollerarevalidatedandtheon-lineelectricparametersmonitorstrategyis

    ;discussed.Therea1vehicleexperimentresultsindicatethatthehighvoltagesafetymanagement

    ;systemdesignedissuitableforEVapplication.

    ;Keywords:HighvoltagesafetyPrechargeContactresistanceInsulationresistance

    ;Remaimngcapacity

    ;Overthelastseveralyears.airpollutionandenergyshortage

    ;haveledtoanumberofinitiativestodevelopelectricvehicle(EV,

    ;whichusuallyincludespureelectricvehMe(PEV),hybridelectric

;vehicle(HEV)andfue1eellelecicvehicle(FCEV).Batteries.as

    ;themainorassistantpowersourceofEVareusuallyconnectedin ;serieswithhighvoltagetoimprovethedrivabilityandenergy ;efflciency.Thehighvoltageofseriesconnectedba~eriesinsome ;applicationsalmostreachesto600V_Jwhichishienoughto

    ;bringdeadlydangertopeople.Moreoverthecurrentofhigh ;voltagebusisusuallyfromsevera1decadesAmperestohundreds ;0fAmpereswhenthevehicleisoperatingregularly.Ifthereisany ;faultinhighvoltagesystem(HVS1.theconsequenceisseriOUSand ;dangerous.Itisnecessarytodevelopaspecialsystemwhichcan ;monitortheelectricparametersofHVSandimplementthe ;correspondingcontrolstrategyreal-timetoensurethesafetyof ;peopleandvehicle.A1thoughthehighvoltagesafetymanagement ;forseriesconnectedbatteriesisveryimpo~ant,onlyafewstudies ;ofitcanbefound.Amongthesestudies.thehighvoltagesafety ;managementsystemwasmainlyintroducedonitshardware ;design.Thecontrolstrategywasnotdiscussedindetail.Mostof ;themdesignedthehighvoltagesafetycontrolunitbasedonfield ;programmablegatearray(FPGA).Anewconcepthighvoltage ;managementsystemiSintroducedandexplainedindetailinthis ;study.Thecentralcontrolunitisbasedonperiphralinterface ;cOn廿OllerfPIC1whichmakesiteasilytoshareinformationamong ;controllersbycontrollerareanetwork(CAN)andcanimplement ;correspondingstrategyeasily.Inthispaper,ahighvoltagesafety ;managementsystemissummarizedasfourequivalentmodels ;includingprechargemode1.highvoltageinterlock(HVIL)mode1. ;insulationresistancemodelandremainingcapacitymodeland ;analyzedbythehardwareinloopsimulation.Thehighvoltage

    ;safetyconoilerbasedonthe.analysisinthisPaDerhasbeen ;successfullyusedintheCHERYpureelectricvehicle(QRPEV)t ;andthesuperfueleellelectricvehiclefSFCEV).

    ;1HIGHVOLTAGESAFETYMANAGEMENT

    ;SYSTEMSTRUCTURE

    ;Inthisstudy,thehighvoltagesafetymanagementsystemis ;basedonPICMicrochipwhichmakesiteasilytoshare

    ;ThisprojectissupportedbyNationalHi-techResearchandDevelopment ;ProgramofChina(863Program,No.2005AA50102o),andNationalBasic ;ResearchandDevelopmentProgramofChina(973Program, ;No.2007CB209707).ReceivedOctober23,2007;receivedinrevisedform ;February18,2008;acceptedOctober5,2008

    ;informationamongcontrollersbyCANandCallbeeasilyoperated ;bytheflexibleprogramtechnology.Fig.1showsthestructureof ;thehighvoltagesafetymanagementsystem.Thesystemis ;developedtosolvethecfiticalissuesincluding:pre.chargecontro1.

    ;HVILmonitor,insulationresistancemonitorandremaining ;capacitymonitor.Threerelays(Pre.relay,Relav+andRelay1

    ;controltheprechargeprocessandRelay+&Relaymanagethe

    ;highvoltageoutputofseriesconnectedbatteries.Thehighvoltage ;impulsecanbeavoidedwhenthethreerelaysarecontrolledby ;thelogicalcoilolorder.HVILcheckstheconnectionstatusof ;highvoltagebusbymeasuringthecontactresistanceofhigh ;voltagebus.Thehighvoltagesafetymanagementsystem ;monitorstheinsulationresistancebytheknownresistancewhich ;isinsertedbetweentheterminalsofbatteryandground.In ;ordertomonitorremainingcapacity,anequivalentcircuitmode1 ;iSestablishedtocalculatetheresidua1energy.Twocommunica. ;tionmodesareadoptedtoimprovethesystemreliability,oneis ;CANwhichhasthehigherpriorityandtheotherisstate1ine.The ;hivoltagesafetymanagementsystemistheintegrationof ;electricparametersmonitorandfaultsdiagnosis.Thediagnosis ;codeisdisplayedbythecombinationofA.BandCshownin ;Fig.1.

    ;L——

    ;Fig.1Structureofthehig}lvoltagesafetymanagementsystem ;?64?QIANGJiaxi,etakHighvoltagesafetymanagementsystemofelectricvehicle

    ;2EQUIVALENTCIRCUITMODELS

    ;2.1Pre-chargemodel

    ;IftherelaysfRelay+&Relay_)areswitchedondirectly,the ;highvoltagewillimpulsetheelectricsystemfortheinput ;capacitanceofhighvoltageequipment.Moreover,ifthereisany ;faultwimHVS.itwillcausethedangerousaccident.The ;prechargeprocesscansolvetheseproblems.Thespecificmethod ;isthatbeforeeachstartprocess,Pie.relayandRelay(shownin

    ;Fig.11aleclosedfirst.IfthevoltagebetweenHV+andHV

    ;reachescertainvalue(90%ofBP’svoltagedefinedinthisstudy1

    ;intime.Relay+andRelayarepermittedtobeclosedand

    ;Pre-relayiscutoff,orallrelaysarecutoffandoutputsthe ;pre.chargefault.Thepie.chargemodelshowninFig.2is ;proposedthroughanalyzingtheHVSconfigurationand ;prechargecurves13-4J.InFig.2,Ubisthevoltageofbatterypack, ;Rbisthebatterypackinternalresistance,1ispre-charge ;resistance.R,isequivalentresistanceofHVSandCisthe ;equivalentcapacitanceofHVS.Amongtheseparameters.gucan ;bemeasured.Rbisverysmal1.Duringtheprechargeprocess,all

    ;equipmentsareforbiddentoworkwhichmeansR2isverylarge. ;Inordertosimplifythecomputing,RbandR2areignored ;accordingtotheabovediscussion.Theprechargemodelshown

    ;inFig.3issimplifiedasFig.2shows

;

    ;b

    ;_[:I_Fig.3Simplifiedprechargemodel

    ;AccordingtotheKirchhoff’slaw,thereare

    ;Ub:U+U

    ;=Ri

    ;i:Cd/dt

    ;BythecombinationofEqs.(1)--(3),thereis

    ;RCdU./dt+Uc

    ;=Ub

    ;Consideringtheinitialconditionthatt=0,0

    ;Uc=Ub『】_exp(一志)]

    ;S0theequivalentcapacitancecallbecalculatedas ;c:t/[R~OU/U)

    ;whereUb——Banpackvoltage

    ;——

    ;Pre-chargeresistancevoltage

    ;——

    ;EquiValentcapacitancevoltage

    ;——

    ;Pre.chargeresistance

    ;i——Pre.chargecurrent

    ;C——Eauivalentcapacitance

    ;t——Pre.chargetime

    ;(1)

    ;(2)

    ;(3)

    ;(4)

    ;(5)

    ;(6)

    ;Accordingtotheactualprechargeprocess,theequivalent

    ;capacitanceofHVScanbecalculatedaccordingtotheknown ;prechargeresistanceandpre?chargetime(.Thenthepie-charge ;resistancecanbeselectedbasedonthecalculatedequivalent ;capacitanceandactualsituationtominimizethepre?chargetime. ;2.2H?Lcontrol

    ;HVILcheckstheconnectionstatusofhighvoltagebus.Two ;parallelmethodsareusedinthisworktoimprovethesystem ;reliabillty.Thepositionwhereiseasyto1oseconnectionsuchas ;connectorsshowninFig.1uses1OWvoltagecircuitloopto ;measuretheaccuratecontactresistance.Atthesametime,the ;overallcontactresistanceisalsocalculatedaccordingtothe ;variablevoltageandcurrent.TheequivalentHVILcalculation ;modeIisshowninFig.4.InFig.4.thebatterymodeIissimplified

    ;astheseriesconnectionofunitvoltageSOurCeUb,batterypack ;internaIresistanceRb,1ineresistanceR,andthevoltageof ;HVSfV1.

    ;.

    ;Fig.4HVILmodel

    ;AccordingtotheKirchhoff’slaw,thereis

    ;Rb+R=(UbU)/1(7)

    ;AssumingthatthevoltageofHVSisUI1andcurrentisI1in ;timesteptl,andthevoltageofHVSisU22andcurrentis,2intime ;stept2.Thereare

    ;Rb+R=(UbUI1)/Il(8)

    ;Rb+R:(UbU22)/12(9)

    ;BythecombinationofEqs.(7)--(9),thereis

    ;Rb+R=(U22Ul1)/(II,2)(10)

    ;whereh_Batterypackinternalresistance

    ;R——Lineresistance

    ;C——Batterypackvoltage

    ;1——Terminalvoltageintimestept1

    ;U22——Tennina1voltageintimestept2

    ;——

    ;Buscurrentintimesteptl

    ;/2——Buscurrentintimestept2

    ;ThelineconnectionstatuscanbecheckedbyEq.(1O).The ;faultlevelofconnectionstatusisdifferentiatedaccordingtothe ;differentcontactresistance.ThedrawbackofEq.(10)isthatthe ;internalresistanceRhofbatterypackisvariablewhentheambient ;temperatureandstateofcharge(SOC1isdifferent.Therefore.the ;prudentmethodadoptedinthisstudyisthattheRbisinterpolated ;formthetablewhichismadeupOfRb,temperatureandSOC ;recordedinthe1aboratory.ThenitisreasonabletotrustR ;calculatedfromEq.(10)hasthehighaccuracyifvoltageand ;currentaremeasuredaccurately.

    ;2.3Insulationresistancemodel

    ;TheinsulationresistanceiSthekeyparametertoevaluatethe ;highvoltagesafetystate.Iftheinsulationleve1islow,passengers ;maygetelectricshock.Accordingtothestandard.theinsulation ;resistancemustbegleaterthan100Q/VpJ.Theinsulation ;resistancecalculationmodelisshowninFig.5.

    ;InFig.5RispositiveinsulationresistanceandRis ;negativeiasulationresistance,isthevoltageofbatterypack. ;CHINESEJOURNALOFMECHANICALENGINEERING?65?

    ;WhentheswitchKoandtheK1areopen,thevoltagesofRpandRn ;areU2andUlrespectively,accordingtotheKirchhoff’slaw,there

    ;are

;Ul/R=U2/(12)

    ;whereUI——,b1tageofnegativeinsulationresistancewhenthe ;switchK0andtheK1areopen

    ;(——?)ltageofpositiveinsulationresistancewhenthe ;switchKoandtheK1areOl;)en

    ;——

    ;Banerypackvoltage

    ;R——Negativeinsulationresistance

    ;——Positiveinsulationresisitance

    ;Fig.5Calculationmodelofpositiveinsulationresistance ;R0isaknownresistancewhichisinsertedbetweenbakery ;terminalandgroundinFig.5.TheinterferenceofRoshouldnot ;changetheinsulationlevelofHVS.WhentheswitchK0isclosed ;andtheK1isopen,thevoltagesofRpandRnareU2andUI ;respectively,accordingtotheKirchhoff’slaw,thereare

    ;c,UUb(13)

    ;Fig.6Remainingcapacitymodel

    ;Intheinitialstate:t=0,UcU0,U0isequaltothevoltageof ;batterypackbeforetherelaysarecutoff.

    ;Thecapacityreleasetimecanbecalculatedbythe ;combinationofEqs.(17)--(t9)

    ;t=CR(InUoInUt)(20)

    ;TheequivalentcapacitanceCofHVScanbecalculatedby ;Eq.(6).Assumingthatthevoltageofhighvoltagebusisat ;timesteptafterrelaysarecutoff,theresidualenergyWcallbe ;calculatedas

    ;W=C,/2(21)

    ;where——ltageoftheequivalentcapacitanceofthehigh ;voltagebus

    ;一一

    ;V01tageoftheequivalentresistanceofthehigh ;voltagebus

    ;R——Equiva1entresistanceofthehighvoltagebus ;f——Capacityreleasetime

    ;U——V_01tageofhighvoltagebusisUattimestept ;C——Eauivalentcapacitance

    ;——

    ;Residua1energy

    ;3EXPERIMENTVALIDTIoNAND

    ;(14)DISCUSSION

    ;where——v0ltageofnegativeinsulationresistancewhen ;theswitchK0isclosedandtheK1isopen

    ;:一一Vbltageofpositiveinsulationresistancewhen ;theswitchKoisclosedandtheK,isopen

;n——KnO,vllinsertedresistance

    ;AccordingtoEqs.(11)-(14)andtheknownRo,theformula ;whichcancalculatethepositiveinsulationresistanceisdefinedas ;(U2]

    ;Thenegativeinsulationresistanceisdefinedas

    ], ;R=

    ;Also,thepositiveandnegativeresistancescanbeobtainedin ;thefollowingstate:@K0andKlareopen,K0isopenandK1is ;closed.?K0isopenandKlisclosed,K0isclosedandKlisopen. ;2.4Remainingcapacitymodel

    ;纾毋entherelaysarecutoff,theremainingcapacitymainly ;concentratesintheequivalentcapacitanceofthehighvoltagebus. ;Fig.6showstheremainingcapacitymode1.Ucisthevoltageof ;theequivalentcapacitanceofhivoltagebus,URisthevoltage

    ;oftheequivalentresistanceofhighvoltagebus.Zistherelease ;current.

    ;AccordingtotheKirchhoff’slaw,thereare

    ;=

    ;UR=Ri

    ;i=Cd/dt

    ;Ahardwarein?loopsystemshowninFig.7isdevelopedto

    ;validatetheproposedequivalentcircuitmodelsandstudyonthe ;controlstrategy.Signalsinthehardware?-in??loopsystemarelisted ;andexplainedasfollows.

    ;Fig.7Circuitstructureschematicdiagramofhighvol~gesafetytest ;r17,ANmatchedresistance,Rn--Simulatednegativeinsulationresistance, ;Rp--Simulatedpositiveinsulationresistance,R1Pre.chargeresistance,

    ;f181I_Releaseresistance,Contactresistance,Loadcapacitance,

    ;1,Highvoltagerelays,Prcchargerelay,K4,一【nsulationtest

    ;(19)relays,K6--Releaserelay,A12~/34Hallsensorforcurrentmeasurement ;???

    ;f???I

    ;,

    ;

    ;lI

    ;+

    ;?66?QIANGJiaxi,etal:Highvoltagesafetymanagementsystemofelectricvehicle

    ;(1)Nineanaloginputsignals.Fivevoltagesignals:the ;voltagebetweenbatterypositiveterminalandground,thevoltage ;betweenbatterynegativeterminalandground,theoutputvoltage ;betweenpositivehighvoltagebusandground,theOHutvoltage

    ;betweennegativehighvoltagebusandground,theoperating ;voltageofhighvoltagesafetycontroller(U+).

    ;Fourcurrentsignals:thecurrentofpositivehighvoltagebus,

    ;thecurrentofnegativehighvoltagebus,thecoilcurrentof ;positiverelay,thecoilcurrentofnegativerelay. ;(2)Sixinputswitchsignals.Threehighvoltagesafety ;controllercommandstomanagetheoutputofhighvoltage:WUP- ;CMD1,CMD2.

    ;Threehighvoltagesystemstatestodisplaythediagnosis ;code:A,B,C.

    ;(3)Sixoutputswitchsignals:K1,K2,K3,K4,K5,K6. ;3.1Experimentandanalysisforpre-ehargemodel

    ;Fig.8shOWSthepre.chargecurves.Thetestconditionis:the ;voltageofbatterypackis420Vtheprechargeresistanceis

    ;8364Qandtheequivalentcapacitanceis330IxF.Thepre-charge ;timerecordedis6.5sandthetheoreticalvaluecalculatedbythe ;pre.chargemodelis6.36s.Thefactindicatestheaccuracyofthe ;pre.chargemode1.InFig.8.thecoilcurrentofrelayisalso ;monitoredbecauseitcanindicatetheworkingstateofrelay.Two ;Deakcurrentpulsesindicatetheclosesequenceofrelaysduring ;pre-chargeprocess.

    ;

    ;

    ;

    ;

    ;0

    ;Timet/s

    ;Fig.8Testtrialcurveofhighvoltageprecharge

    ;TheconastivetestresultsareshowninFig.9toanalyzethe ;controlstrategYforprecharge.Thevoltageofbatterypackis326 ;Vinthecontrastivetest.Thepre.chargeresistanceis8364f2and ;theloadcapacitanceis330I.tFinFig.9a.3637Qand660laFin ;Fig.9b.3637Qand330gFinFig.9c.Duringthetestcirculation. ;therecordedpre.chargetimeofeachtestis6.1s.5.3sand2.7s ;respectively,andthecalculationerrorofloadcapacitanceis ;

    ;3.6%.1.8%and0.6%.Throughanalyzingthedifferenttest ;curvesinFig.9.twovisualizedconelusionscanbeobtained: ;theshortertimeprechargecosts.thelesserrorofloadcapacitance ;calculation;(2)thelessvalueofpre.chargeresistanceandload ;capacitance,theshortertimeprechargecosts.

    ;Itisvaluabletoselecttheproperprechargeresistance

    ;accordingtotheactuaIsituationinordertoreducepre.chargetime ;andavoidhighvoltageimpulse.FormFig.9therelaysare ;conolledbythecombinationofcommandsWUCMDland

    ;CMD2.TherelaysarepermittedtobeclosedonlywhenWUPis ;logic”1’’andCMDlandCMD2arelogic…0’.Thiscombined

    ;commandmethodcanavoidmishandlingandinterference. ;3.2ExperimentandanalysisforBVILmodel

    ;TheHVILmodeldiscussedinsection5isthecombinatiOnOf ;batteryinternalresistanceandlineresistancemonitor.Itis ;necessarytoconsiderthevariablebatteryinternalresistance ;influencedbySOC,temperatureandcharge/dischargecurrent.A ;wisemethodadoptedinthisstudyisthatthewholeHVSistested ;inthelaboratoryundersimulatingthecomplicateddrivecycle.

    1.0 ;ThesafecontactresistancerangedefinedinthisworkiS0.2

    ;accordingtotheexperimentalresults.Thecontactresistance ;computedbyEq.f1O,isbasedonthecautiouschoiceofreferenced ;current(1l,,2)andvoltage(Un,Ul2).Aseriespointsofcurrent ;andvoltagearerecordedduringactualdrivecycletoanalyzethe ;HVILmode1.Tworeferencedcurrentpoints00.4Aand129.6A1 ;areselectedtocalculatethecontactresistancewhichisshownin ;Fig.10.FromFig.10.almostal1thecalculatedpointsareinthe ;saferange.Theabnormalpointsareselectedouttobecompared ;jnTab1e1.

    ;28

    ;21

    ;7

    ;0

    ;35

    ;3?6

    ;2,8

    ;1.2u

    ;.4

    ;-

    ;0.4

    ;3?6

    ;2.8

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