ESSPreliminaryDesignReview

May20,2015

Year One Communications Plan (Feel free to add some school spirit to the title page)

Team:

Date:

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Year 3: Progress Report 3

April 10th, 2014

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TABLEOFCONTENTSTableofContents........................................................................................................................................I

TableofFigures..........................................................................................................................................II

ListofTables...............................................................................................................................................II

TableofAcronyms......................................................................................................................................II

ProjectPlan................................................................................................................................................8

ESSTimingPlan......................................................................................................................................8

ESSDesignManagementProcess...........................................................................................................8

RisksandRiskMitigationPlans...............................................................................................................8

VehicleArchitectureOverview...................................................................................................................9

PowerflowDiagram................................................................................................................................9

Vehicle-LevelRequirements...................................................................................................................9

Enclosure/MechanicalPackaging.............................................................................................................9

PackagingofBatteryHardware..............................................................................................................9

SealingandVenting..............................................................................................................................11

LVandHVWireRouting.......................................................................................................................13

CoolantLineRouting............................................................................................................................14

ComponentMounting..........................................................................................................................14

ESSAssembly........................................................................................................................................16

ElectricalDesign.......................................................................................................................................22

HVSchematic........................................................................................................................................22

HVInterlockLoop.................................................................................................................................23

ElectricalIsolation.................................................................................................................................24

Safety.......................................................................................................................................................24

PreliminaryFailureMode.....................................................................................................................24

MSDPlacement....................................................................................................................................25

FingerProofingandSecondaryCover..................................................................................................26

ThermalSystem........................................................................................................................................27

RequirementsforBatteryThermalPerformance.................................................................................27

CoolingMethod....................................................................................................................................28

InitialThermalSystemAnalysis............................................................................................................28

Charger.....................................................................................................................................................30

CompatibilitywithBatteryHardware...................................................................................................30

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EMI...........................................................................................................................................................31

DesignFeaturestoMitigateEMIImpacts.............................................................................................31

Appendix..................................................................................................................................................32

SupplementaryESSDesignCADImages...............................................................................................32

SupplementarySchematics..................................................................................................................43

TABLEOFFIGURESFigure1ESSGANTTchart...........................................................................................................................8Figure2:FMEATable.................................................................................................................................8Figure3:PowerFlowDiagram...................................................................................................................9Figure4:CompleteESSassembledinvehicle..........................................................................................10Figure5:Structuralsupportrailsattachedtovehicleframe....................................................................11Figure6:Detailviewofsealinginterfaceandlatches..............................................................................12Figure7:Pressurereliefvalvelocation....................................................................................................12Figure8:Lidinterfaceatcenterofthebatterypack,clampandlidsealvisible......................................13Figure9:LocationofHVpacksideconnectorallowingsimplewireroutingtojunctionbox..................14Figure10:BatteryModulemountingwithindexingstructurevisibleinyellow......................................15Figure11:Removablecontrolhardwareshelfwithcomponentsattached.............................................16Figure12:Viewofcontrolhardwareshelfinstalledinpack....................................................................16Figure13:ESSHVSchematic....................................................................................................................23Figure14:HVILSchematic........................................................................................................................24Figure15:ESSDFMEAChart.....................................................................................................................25Figure16:Interlockingtwoliddesign......................................................................................................26Figure17:MSDlocationfrontview..........................................................................................................26Figure18:Tempriseat50%SOC.............................................................................................................29Figure19:TempRiseat10%SOC.............................................................................................................29Figure20:SimscapemodelofESS............................................................................................................30

LISTOFTABLESTable1Acronyms.......................................................................................................................................IITable2:ChargeCurrentLimits.................................................................................................................27Table3:DischargeCurrentLimits............................................................................................................28

TABLEOFACRONYMSTable1Acronyms

Acronym MeaningBEV BatteryElectricVehicleBCM BatteryControlModuleCSM CurrentSenseModuleCAD Computer-aidedDesign

III

CD ChargeDepletingCS ChargeSustainingDC DirectCurrentEDS EmergencyDisconnectSwitchEDM ElectronicDistributionModuleEMI ElectromagneticInterferenceESS EnergyStorageSystemEREV ExtendedRangeElectricVehicleEV ElectricVehicleFt FeetFMEA FailureMode&EffectsAnalysisG GravitationalConstantHV HighVoltageHVAC Heating,ventilation,andairconditioningHVIL HighVoltageInterlockLoopICE InternalCombustionEngineIVM InitialVehicleMovementKm KilometerL Liter

MSD ManualServiceDisconnectMVEC MultiplexedVehicleElectricCenterNYSR Non-YearSpecificRulesPHEV Plug-inHybridElectricVehicleSec SecondRPN RiskPriorityNumberSOC StateofChargeVTS VehicleTechnicalSpecificationsUW UniversityofWashingtonWh Watt-hour

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PROJECTPLANESSTimingPlanError!Referencesourcenotfound.showstheEnergyStorageSystem(ESS)GANTTchart,whichdisplaysatimescheduleofkeyactivities

andtasksintegraltotheESSdesignandintegrationprocessfromyear1throughyear2.Thelegendatthetopofeachchartshowscolor-markedsquaresdefiningplanning,actual,andcompletestagesoftheproject.Theplanningstageofaprojectdefinessettingupaprocedureanddeadline,whichtypicallyonlytakesaweekdependingontheactivity.Theactualstageoftheprojectiswhentheteamstartsfulfillingtheplanandimplementingtasks.Andthecompletestageoftheprojectmarkstheexpectedprojectdeadline.ThedesignprocessbeginsinAprilofyear1andfinishesthebatterypackintegrationprocessneartheendofAprilofYear2.Keybatterypackdesignactivitiessuchastheenclosuredesign,modulearrangement,component-shelfdesign,andpowerrequirementsarestaggeredacrossAprilallbeforePreliminaryDesignReview(PDR)SubmissionbeginsinearlyMay.OncePDRandFDRSubmissionarecomplete,weplantoorderthesekeycomponentsthroughA123andvariousothersourcesinmid-July.AtthebeginningofYear2FallQuarter,theelectricalteamwillassemble,test,andadjusttheBatteryPackuntilwereceivetheChevrolet2016CamaroinlateNovemberorearlyDecember.Finally,theBatteryPackInstallationisplannedtobegininJanuaryandstretchthroughtheendofAprilbeforeYear2Competition.

Figure1ESSGANTTchart

LEGEND: Plan Actual CompleteEach year starts in September (Quarter System)

Year 1 2

MONTHS Apr. May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr.

ACTIVITY %COMPLETE WEEKS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52Enclosure Design 100%Module Arrangement 100%Component Shelf Design 100%Power Requirements 100%PDRSubmission 100%Cooling Plan & Simulation 50%Connector Placement & Wire Routing 25%PartSourcing 25%FDRSubmission 0%ReceiveA123Parts 0%ReceiveSourcedParts 0%Outsourcingmanufacturing 0%AssembleBatteryPack 0%ReceiveCamaro 0%BenchTest&BalanceBatteryPack 0%BatteryPackInstallation 0%

ESS Time Schedule

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ESSDesignManagementProcessTheelectricallead,JakeGarrison,isprimarilyresponsibleforoverseeingthebatterypackdesignandintegrationintheChevrolet2016CamarothattheUWEcoCARwillreceiveattheendofthisyear.TheaboveGANTTchartbroadlyoutlinesthetimingplanfortheESSbatterypackdesignandintegrationoverthecourseofthisyearandnextyear’sEcoCAR3competition.Theworkonthedesignandintegrationofthebatterypackissplitintotwosub-teams:mechanicalandelectrical.MatthewPalmerisinchargeofthemechanicalteamworkingonthisproject,anddirectlyreportshisprogresstoJakeGarrison.Matthewhasfullpowerovermakingdecisionsonmaterialdesign.Alldecisions,however,mustbeapprovedbyJakeGarrison.WhileJakeGarrisonhasexecutivepowerandauthorityoverthisproject,hisworkonthedesignandintegrationwillbereviewedbytheengineeringteamleadsandourfacultyadviserProfessorBrianFabien.Openissuessuchascomponentsourcingwillbehandledwithaweeklymeetingofelectricalteammemberswhoarepresentforthesummer.TheelectricalteammembersinthelabwillalsosendaweeklyreporttoJakeGarrisontoupdatehimonkeyactivities/tasksaswellastoaskanyquestionsinlightofuncertainty.Intimesofuncertainty,JakeGarrisonwillreachouttooneoftheorganizeradvisers,JesseAlley,foradviceandguidance.RisksandRiskMitigationPlansUWEcoCARusesFailureModeandEffectsAnalysis(FMEA)toconduct,organize,andassessriskanalysis.TheFMEAtableshowninFigure2calculatesaRiskPriorityNumber(RPN)bymultiplyingtherisks’severitybyitschanceofoccurrencebyitsdifficultyofdetection.Eachoftheabovecategoriesarequantifiablyrankedfromascaleof0-10,meaningthehighertheRPNthehigherrisk-levelitrepresents.Belowisalistofbatterypackdesignriskswiththeireffectsandrootcausesaswellasrespectivecontingencyplansintheeventoftherisks’occurrence.Thehighest-levelriskwiththebatterypackdesignisthepotentialissuewithaninadequatecoolingsystem,whichcanresultintheoverheatingofthebatterypack.Thisrepresentsasignificantriskinitsseverityanddifficultyofdetection.Throughcarefulplanninganddesignefforts,theteamhasmanagedtoreduceallriskschanceofoccurrencetoarelativelylownumber(1-3range),thusproactivelylesseningRPNsofESSrisks.

Item: Battery Pack Design

Involved Teams:

WrongDimensionsUnabletomount,setbackincostandtime,andrequiresredesign

7IncorrectprocessingofCADtodesign

3 2 42MoreintensiveCADprocessingandredesign

Unabletoimplementduetosizeconstraint

NotMeetForceConstraints

Packdesigndoesnotpasstheefficientdesignreview,setbackintime

5Lackoftrainingandforesightinchoosingmaterials

2 1 10 RedesignmaterialselectionIdentifiedeitherbydesignreviewpaneloroursimulations

CoolingSystemInadequateCoolingSytem

Overheat 7Lackofairflowfrompoordesign

3 8 168 Addfansandventsinternally Testingonthevehicle

HighVoltage SafetyShockandteammemberinjury

10Poortraininganddesignisasafetyrisk

1 1 10Trainingtutorialsandmandatorytestingonrulesoutlinedinsafetybinder

Quarterlytrainingfornewmembers

NotfitsizeconstraintNotservicableandnotsafe

4Poordesignandforesight

5 1 20Explorealternativeoptionsforconsumeracceptability

Notbeingabletoofitsuitcasesincar,andnotbeingabletoservicepackasneeded

ConflictwithrulesSetbackfromgettingpackcertifiedbycompetition

6Miscommunicationsbetweenorganizersandteam

2 1 12Thoroughcommunicationswithorganizerstoconfirmcompliancewithrules

Periodicemailsandcallstoorganizers

Packaging

EnclosureDesign

ProcessFunction PotentialFailureMode PotentialEffect(s)ofFailure

Sev

PotentialCause(s)/Mechanism(s)of

FailureContingencyPlan ContingencyPlanTriggers

FAILURE MODE AND EFFECTS ANALYSIS

All engineering teams

Occur

Detec

RPN

Figure2:FMEATable

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VEHICLEARCHITECTUREOVERVIEWPowerflowDiagram

Figure3:PowerFlowDiagram

Vehicle-LevelRequirementsInordertoachievetheperformancedesired,UWEcoCARhaschosentouseanA123batterypackwith7x15s3pconfiguration.Thispackgivesthehighestpoweroutputanditisalsothemostpackageablesetupavailablefortheteam’sapplication.Thispackisratedat58.8Ahincapacityand18.9kWhinenergy,whichprovidesaround50milesofEV-range.Inaddition,thissetupprovidesapeakpackvoltageof375Vandpeakcurrentof612Afor10seconds,whichisdesiredforanaccelerationof5.3secondsfromIVM-60mph,2.9secondsfrom50-70mphandatopspeedof85mph.

ENCLOSURE/MECHANICALPACKAGINGPackagingofBatteryHardwareAtthebeginningofthisproject,theteamestablishedspecificgoalstooptimizetheintegrationwiththeexistingstructure,thepracticalityofassembly,andtheeaseofserviceability.ThesethreethemesgovernedthedecisionmakingforallsectionsoftheESSpack.

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Figure4:CompleteESSassembledinvehicle

Thepackwillfitwithinthevehiclestructurebyutilizingatiereddesigntoconformtotheshapeofthevehicle’stieredtrunk(SeeFigure4).Itwillconsistoffrontandrearhalvesthatwillberigidlyconnectedtoformtheenclosure.Thepackwillbesealedandcoveredwithatwo-piecelid.Thepackitselfwillbeattachedtofoursupportrails,stretchingbetweentheframerailsoneachsideofthevehicle(SeeFigure5).Tabswillbeweldedtotheexistingvehicleframethatwillallowthesupportrailstobeattachedtothevehicle.Theseweldedtabsandrailswillbedesignedandanalyzedtoensuretheymeetthestructuralrequirementsofthe8Gverticaland20GlateralstaticloadconditionswhentheESSpackisfullyinstalled.

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Figure5:Structuralsupportrailsattachedtovehicleframe

TheenclosurewillbeconstructedfromaluminumsheetandthetwolidswillbeconstructedfromBoltaron™.Aluminumischosenforitsstrengthandeaseofmanufacturing,andBoltaron™ischosenforitsabilitytobeformedintocomplexsurfacesanditslowelectricalandthermalconductivity.Insidethepack,thebatterymoduleswillbeorientedintworows.Theupperhalfofthepackwillhousearowof4moduleswhilethelowerhalfwillhousearowofthreemodules.Eachofthesetworowswillbemountedtoasecondarystructureinsidetheenclosuredesignedtofixthemodulestothestructuralsupportrailsandprovideevenspacingbetweenthemodules.SeetheComponentMountingsectionforfurtherdetailsonthissubsystem.TheotherESScomponentsincludingtheBSM,CSM,EDM,andMSDreceptaclewillbemountedonaremovableshelfwithintheenclosure.Thisshelfwillmountdirectlyabovethebatterymodulesinthelowerenclosure(SeeFigure11).Itwillallowforeasyassembly,effectiveuseofspace,andsimpleservicing.Serviceandinstallationofthebatterymodulesintheenclosurecanbeperformedfromeitherthetrunkorthroughtherearpassengerseatopening(seeAppendix:SupplementaryESSDesignCADImages).Thetwo-piecelidsecuredbydrawlatcheswillallowforeasyaccesstotheinsideoftheenclosure.Clearancesbetweentheenclosureandthesurroundingtrunkstructurearerelativelysmall,buttheenclosureiscapableoffittingwithintheacceptablelocationsdefinedbytheNYSRandnoportionoftheESScomponentsarelocatedinthedesignatedcrushzones(seeimagesinAppendix:SupplementaryESSDesignCADImages).SealingandVentingThebatterypackwillbesealedtopreventboththeingressandexitofvapors,moisture,andcontaminants.Theinterfacebetweentheenclosureandthelidwillbesealedbysiliconrubberedgetrim.Thelidwillbeclampeddownwithspringdrawlatchesthatwillmaintainclampingforceonthelidandthusguaranteethatthelidremainssealedeveninthecaseofpositivepressureinsidethepack(seeFigure6).Allholesthroughtheenclosurewillhavegasketsorothersealants.

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Figure6:Detailviewofsealinginterfaceandlatches

TheESSdesignalsoutilizesaninlinepressurereliefvalvelocatedadjacenttothepackside-HVconnector(seeFigure7),thatwillmaintainthepacksealbutallowinternalpressureandoff-gassingtoberoutedoutsideofthepassengercompartment.

Figure7:Pressurereliefvalvelocation

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Figure8:Lidinterfaceatcenterofthebatterypack,clampandlidsealvisible

LVandHVWireRoutingThewireroutingwithintheESSistobeimplementedwithsafety,serviceability,andprotectionofcomponentsinmind.Specifically,thephysicaldesignofspansofcable,connectionsandterminals,andwireintersectionsshalladheretotherelevantsectionsoftheNYSR,whilealsoservingtheteam’spurposeandmodularESSdesign.ThefollowingguidelinesandideasareinfluencedbytherelevantsectionswithintheNYSR(I-3DesignRulesforHighVoltageSystems,I-4DesignRulesforEnergyStorageSystems),andareadaptedtotheteam’sspecificpackconstruction.AswireroutingwithintheESSisstillintheconceptualstageandnodesignshavebeenmadeconcrete,manyoftheseguidelineswillrequirefurtheranalysisandperhapsrevision.Theteam'snexttaskistoincludewireroutinginCADmodeltosolidifythefinalstrategy.HVExteriorConnection:ThemodulardesignoftheESSallowsforoptimalpositioningoftheHVterminal.Theterminalisplacedsuchthattheinternalpositiveandnegativecablesareunderlowbendstresswhenaccommodatingtheconnection.Theexteriorterminalfacestowardthefrontofthevehicleandiscenteredalongthevehicle,whichallowsforoptimalconnectingtotherearjunctionbox.Thecableshieldingisalsofedthroughthisconnector(SeeFigure9).

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Figure9:LocationofHVpacksideconnectorallowingsimplewireroutingtojunctionbox

LVExteriorConnection(NotyetinCADmodel):DesignconsiderationsforthisconnectionincludemitigationofEMIonLVcommunicationssignals,andexternalroutingoptimization.TheLVconnectorislikelytobeplacedontherearportionoftheenclosure,oneithertheleftorrightside.Internally,thisallowsLVcommunicationlinestohaveoptimaldistancefromHVcablestomitigateEMI(SeeEMISection).Externally,theconnectorroutestheLVthroughthepassengercompartmenttowardsthesupervisorycontrollerinthefrontofthevehicle.PossibleShelfConfigurations:InordertoreducetheamountandcomplexityofHVlinesaroundtheshelfareaoftheESS(wheretheCSM,MSD,BCM,andEDMarelocated),theteamisconsideringafewdifferentoptionsintermsofinterfacingshelfcomponentswithconnectionsfromthebatterymodules.Inordertoconnecttheshelftothemodules,thedesignwilleitherhaveconnectionsaroundtheedgeoftheshelfupfromthemodules,orcomingthroughtheshelf.Witheitheroftheseoptions,theteamstillhastheissueofconnectingeachshelfcomponent.Powerdistribution(busbars)thatsitsontheshelfmaybeonesolution.Thiswouldinvolvehavingcustomlaminated/insulatedbusbarsinsteadofcableroutingthatcouldbecustom-builtbyMersenfortheteam’sapplication.Othersolutionsmayincludesimplykeepingseparatecables,orre-arrangingshelfcomponentstooptimizespaceusageandensuretheteamisnotcompromisingonminimumbendradiusof1/0cable.Forreference,theChamplainEXRAD1/0hasaminimum-bendingradiusof105mm,orapproximately4inches.CoolantLineRoutingUWESSwillutilizepassivecooling.RefertoThermalSystemsectionforadditionaldescription.ComponentMountingInsidethepack,thebatterymoduleswillbemountedtoaninternalstructurethatwillallowforevenspacingandsturdyattachmentofthemodules(SeeFigure10).Thisstructurewillbeconstructedfromaluminumandwillbemountedthroughtheenclosuredirectlytothesupportrails.Themountingstructurewillalsoutilizeapolycarbonateindexingstructurethatwillaidinaligningthemodulesduring

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assemblyandmaintainingmodulespacing.Eachmodulewillbespacedaminimumof10mmfromadjacentmodulesorenclosurewallsoneitherside,allowingforthermalexpansionandcoolingofthemodules.ThissecondarybatterymodulemountingstructureandconnectionswillalsobedesignedandanalyzedtoensurestructuralrequirementsspecifiedbytheNYSRaremet.Additionally,allthehardwareusedtoattachtherails,enclosure,andmoduleswillbeclass12.9andlockinghardwarewillbeusedwhereapplicable.

Figure10:BatteryModulemountingwithindexingstructurevisibleinyellow

TheBCM,CSM,EDM,andMSDreceptaclewillbefixedtoaremovablepolycarbonateshelf(SeeFigure11:Removablecontrolhardwareshelfwithcomponentsattached)andwillbeassembledoutsideoftheenclosureforconvenient,safeassembly.Aftereachcomponentisattached,theshelfismountedintheenclosureabovethelowerrowofbatteriesandissupportedatthecornersbyfourmountingbrackets.FurtherdiscussionoftheMSDmountingcanbefoundintheSafetysection.

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Figure11:Removablecontrolhardwareshelfwithcomponentsattached

Figure12:Viewofcontrolhardwareshelfinstalledinpack

Theplacementoftheshelfwillbeabovethelowerassemblyofbatteriesforeaseofservicing(SeeFigure12).Additionally,alllowerbatteriescanbeaccessedbysimplydisconnectingandremovingtheshelffromtheenclosure.Thisassemblygivesthebestbalanceofspaceconservationandaccessibility.ESSAssembly1. Weldstructuralattachmenttabsontopofvehicleframerails.InstallsupportrailsinCamaro,twoin

thefrontofthetrunkrightbehindtherearseatandtwointhesparetirewell.Bolttherailstothetabs.

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2. InstalltheHVconnectorandpressurereliefvalveonthefrontoftheloweraluminumenclosure.Lineinteriorofbothenclosureswithelectricallyinsulatingmaterial.(SeesectiononElectricalIsolation)

3. Installbothaluminumenclosuresinthevehicletrunkontopofthesupportrails.Bolthalves

together.

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4. Insertbatterysecondarystructureintoenclosures.Attachstructuretosupportrailsbyinstalling

boltsthroughenclosuretounderlyingrails.

5. Mountthebatterymodulestothesecondarystructurewithinslotsdesignatedbytheindex.Install

fourmodulesinthefrontenclosureandthreeintherearenclosure.Oncethemodulesareinplace,

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installboltsthroughmodulesintothesecondarystructure.Installwiringbetweenmodulesaccordingtoschematic.

6. Installshelfmountsflushagainstthesidewallsofthelowerenclosure.

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7. AttachtheCSM,BCM,EDM,andMSDreceptacletothecontrolhardwareshelf.Installwiring

accordingtoschematic.

8. Installtheassembledcontrolhardwareshelfintherearenclosureandbolttothefoursupport

brackets.Completeallnecessaryelectricalwiringandconnections.

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9. Installthelidonthefrontenclosure,ensureproperfitandsealandsecureittotheenclosureusing

thedrawlatches.

10. Installthelidontherearenclosure,ensureproperfitandsecureittotheenclosureusingthedraw

latches.

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11. InstalltheMSDplugontherearlid.

ELECTRICALDESIGNHVSchematicHVschematicofESS(SeeFigure13)showshighvoltageconnectionsbetweenthecomponentsandsomeofthelowvoltageBCMandHVILwiring.Thegenerallayoutofthecomponentsinthefigureissimilartothephysicalmodel.NoticetheMSDsplitsthepack.ForaschematicofourHVsystem,seetherespectivesectionintheAppendix.

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Figure13:ESSHVSchematicHVInterlockLoopThepurposeofHVIListodisconnectthehigh-voltageDCbatteryfromtheelectricsystemtoavoiddamageanddangertothedriver.Thebatterywillbedisconnectedinthefollowingsituations:

• Inertiasensoristriggeredwhenthecarhasaccelerationgreaterthan8G’s,whichistypicalinacrash

• EmergencyDisconnectSwitches(EDS)inthefrontandbackofthecararepressed• LVconnector,HVconnectororMSDisdisconnected• 12Vbatteryfailsorisdisconnected

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Figure14:HVILSchematic

ElectricalIsolationToensurethattheexteriorofthebatterypackiselectricallyisolated,theteamhaschosentousealidconstructedfromBoltaron™withproperlidsealingdescribedintheSealingandVentingsection.Inaddition,theinteriorofthealuminumenclosurewillbecoveredupwithNomex®electricalisolationfoamwhichpreventstheenclosurefromhavingcontactwiththecomponentswithin.Inaddition,thehighvoltageconnectorandtheMSDaredesignedtobefingerproofandacrylicinsertsnearthebatteryterminalswillbeusedtobetterprotectthemaswell(SeethesectiononFingerProofingandSecondaryCoversectionformoreinformation).Finally,allthewiresandbusbarsusedinESSarecoveredwithhighdielectricinsulatingmaterial.

SAFETY

PreliminaryFailureModeTheESSstatusiscontinuouslymonitoredbythesupervisorycontrolsystemtodetectonsetofanyfailuremodessuchasoverheating,groundfault,communicationfailure,faultcurrentetc.TheDFMEApreparedfortheESS(SeeFigure15)describingfailuremodesandsubsequentresponseactionrequiredforavoidinganyfurtherdamagetothesystemservesasthebasisforthefailurediagnosticsignalsfromthesupervisorycontroltothecomponentsandthedriver.

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Figure15:ESSDFMEAChart

MSDPlacementToensurethattheESSissafetoservice,aMSDwillbeincorporatedintothedesign.GreatcareistakenintheconsiderationoftheplacementoftheMSD,asitneedstobeeasilyaccessibleforservicingandmustalsopreventaccesstotheESSwithoutbeingdisconnected.Forthisreason,theMSDplugislocatedontopofthelidoftheenclosureandiseasilyaccessiblefromtheopeningofthevehicletrunk.Thepackisdesignedtohavetwosections,takingadvantageoftheCamaro’stieredtrunkdesign.Tofitintothisspace,thebatteryenclosurewillhaveatwo-piecelid.Thebacklidwillinterlockintothefrontlid,makingitsremovalimpossiblewithoutfirstremovingthefrontlidandtheMSD.

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Figure16:Interlockingtwoliddesign

Inturn,theMSDwillpreventthefrontlidfrombeingremoved.ThisistoensurethatnopartoftheESScanbeaccessedwhilefullyenergized.Toaccomplishthis,thereceptacleportionoftheMSDwillbemountedtotheshelfdirectlybelowthefrontlid.TheplugportionoftheMSDwillpinthefrontlidtotheinternalshelfpreventingthefrontlid'sremovalwithoutdisconnectingtheMSDplug.

Figure17:MSDlocationfrontview

FingerProofingandSecondaryCoverExteriorfingerproofingissatisfiedthroughthetwoBoltaron™lidsandthetwobaseenclosures.Theywillbesealedtogethertightlywithspringlatchestopreventaccess(inpurple,Figure17).AllHV

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exteriorreceptacles(MSD,HVconnectorandTestConnector)aredesignedtobefingerproofaswell.Withintheenclosure,allbatterymoduleterminalsandcomponentterminalswillbecoveredbyinsulatingacryliccoverssecuredbyVelcro.Allwireswillalsobecoveredbyinsulatingmaterial.Finally,asstatedintheElectricalIsolationsection,thepackwillbelinedinhighdielectricNomex®materialtopreventelectricalshortsthroughthealuminumenclosure.

THERMALSYSTEMRequirementsforBatteryThermalPerformanceAccordingtodocumentationsuppliedbyA123,theoptimalperformanceofthe7module15s3ppackoccursatcelltemperaturesfrom20to50°C.ThiscanbevalidatedthroughtheinformationonTable2andTable3.

Table2:ChargeCurrentLimits

Forchargingcurrent,themaximumcontinuouscurrent(60A)canoccurfortemperaturesrangingfrom10to50°CatallSOCanddropsatapproximately2A/degreeCoutsidethatrange.Alsothemaximum10-secchargecurrent(300A)occursfortemperaturesbetween20and50°CforallSOCwithanalmostimmediatedropoutsidethatrange.

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Table3:DischargeCurrentLimits

Fordischargecurrents,themaximumcontinuouscurrent(180A)occursfortemperaturesbetween0and50°CatallSOCanddropsalmostimmediatelyoutsidethatrange.Alsothemaximum10-secdischargecurrent(612A)occursfortemperaturesbetween20and50°Candhaslessofatemperatureeffectasstateofchargeisincreased.Inallcasescellshaveamaximumoperabletemperatureof50°C.Basedontheseresultsitcanbeshownthatthebatterypackperformsclosetoidealattemperaturesbetween20and50°C,withlesseffectsfromSOCwhenattemperaturesabove30°C.CoolingMethodTheUWESSwillutilizepassivecooling.TheteamlearnedthroughEcoCAR2,theprovidedA123docs,andsimulationsoutlinedinthissectionthatthebatteriesoperatemosteffectivelybetween20and50°C,withslightlybetterperformancesabove30°Candthroughpassiveaircoolingtheapproximatemaximumtemperatureriseislessthan20°C.InitialThermalSystemAnalysisTheteambegantheanalysiswithdatafromA123,whichwasderivedfromtestinglogswithoutactivecoolingrelyingonheattransferthroughthepacktoambient.Thefirsttesthadanambienttemperatureof25°C,withcurrentofapproximately48Aand51.5%capacityused.Basedontheseconditionsonlya5°Cincreaseofcelltemperaturewasseenoveraperiodof44minutes.

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Figure18:Tempriseat50%SOC

Thesecondtesthadanambienttemperatureof25°C,withcurrentofapproximately165Aand90%capacityused.Basedontheseconditions15.5°Cincreaseofcelltemperaturewasseenoveraperiodof17.7minutes.

Figure19:TempRiseat10%SOC

Thesetestsshowthatinbothnormalcontinuousoperationandmaximumdischargethatthepackremainsbelowthesafemaximumcelltemperatureincreaselimitof20°Casstatedonthe15s3pmodulespecificationsheetprovidedbyA123.AccordingtothespecificationsprovidedbyA123thepackscellsmustremainwithin8°Cofeachotherforproperoperationandtopreventdamage.Theproposedpackdesignhasauniformdistributionofmodelswhichallowsforevenheatconvectionbetweenthem.Thenextstepofanalysisisthroughmodelingofthesystem.ThemodelconsistsofadualparallelRCcombinationalrepresentationofalithiumioncellwithvaluesderivedfromchargeanddischargecharacteristicsprovidedbyA123.Heatgenerationisdirectlyderivedfrompowerdissipatedthrough

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internalresistanceineachcell.Thesecellsareconnectedina15s3pmodularorientationwiththermalconvectionbetweeneachdirectlyproportionaltosurfaceareaandconvectionheattransfercoefficientforeachcell.Sevenofthesemodulesareconnectedinserieswiththermalconvectionbetweeneachproportionaltosurfaceareaandconvectionheattransfercoefficientforeachmodule.

Figure20:SimscapemodelofESS

Currentlythismodelismissingthenecessarycoefficientsforthermalconvectionbetweencellsandmodulesbasedonaircooling.TheteamisintheprocessofobtainingvaluesfromA123andestimatingparametersbasedontheUWdesign.Currentlythemodelselectricalcharacteristicsandpowergenerationisveryaccurateandmatchesreallogsquiteclose.ThismodelwillbeusedtotestconditionsnotsuppliedbyA123andaddrealisticfactorsrelatedtopackconditions.

CHARGERCompatibilitywithBatteryHardwareTheUWdesignusesawatercooledBrusaNLG5133.7kWonboardcharger.Thechargerhasaninputvoltagerangeof100-264V(48-62Hz)whichisperfectforpracticallyanystandardhomeplugin.The7module15s3pbatterypackhasavoltagerangeof263-378Vandthechargerhasanoutputrangeof200-520Vthusthevoltagesarecompatible.Additionally,thepackhasamaximumchargecurrentof60AandtheBrusachargerhasanoutputchargingcurrentof12.5Awhichmeetscurrentrequirements.BrusaalsohastheoptionofpreprogrammingthechargerfortheA1237module15s3pbattery

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managementsystemandcommunicatesviaCAN,whichmakesitanidealintegration.Thechargerisalsolightweightatonly6.2kgand93%efficientanddirectlydesignedforautomotiveapplications.

EMIDesignFeaturestoMitigateEMIImpactsIndesigningtheESS,appropriatestepswillbetakentoensurethatthefollowingcompetitionrulesareadheredtoinordertoreduceunwantedEMIbothwithinandoutsideofthepack.Oncepreliminarydesignsareaccepted,wewillbeabletosimulateoursystemandconductananalysisoftheEMIeffectsonoursystem.NYSRI-3.6:ExposedHighVoltageandHighVoltageConnections

• ExposingHVsystemsmustnotbeaprerequisiteforaccessingnon-HVsystems• Allshieldedconnectorsmustfollowpropergroundingpracticesandmustbecheckedforlossof

isolationthroughtheshielding.Note:Theteamhaschosentouse1/0ShieldedEXRADHVcableintheinterioroftheESS.ESSEnclosureFortheESSenclosure,theteamhaschosentousealuminumcasingandBoltaron™lid.Inaddition,alayerofNomex®electricalinsulationfoamwillbeusedintheinteriorofthealuminumcasing(asoutlinedinourElectricalIsolationsection).Withthissetup,wecanmitigatetheEMIfromESStotheothercomponentsoutsidetheESS.WireroutingStrategyTheteamisfollowingtherulesoutlinedbelowforwirerouting.Whencircuitscannotbeappropriatelysegregated,theywillbecrossedperpendicularlyinordertominimizeinter-circuitnoisetransmission.NYSRI-3.10:SegregationofHVandLVCircuits

• IfHVlineis<100V,spacingmustbe1cm(0.4in.)• IfHVlineis≥100and≤200V,spacingmustbe2cm(0.75in.)• IfHVlineis>200V,spacingmustbe3cm(1.2in.)

ShieldTerminationStrategyToavoidterminatingcableshieldsinalocationaninconvenientlocation,thecableshieldingwillallbegroundedwithinthejunctionboxoftheESS.

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APPENDIXSupplementaryESSDesignCADImages

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SupplementarySchematics

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