Tesla 2016 Annual Report Download - page 7

Battery Pack
Wedesignourbatterypackstoachievehighenergydensityatalowcostwhilealsomaintainingsafety,reliabilityandlonglife.Ourproprietarytechnology
includessystemsforhighdensityenergystorage,cooling,safety,chargebalancing,structuraldurability,andelectronicsmanagement.Wehavealsopioneered
advancedmanufacturingtechniquestomanufacturelargevolumesofbatterypackswithhighqualityandlowcosts.
Wehavesignificantexpertiseinthesafetyandmanagementsystemsneededtouselithium-ioncellsintheautomotiveenvironment,andhaveactively
workedwithlithium-ioncellsupplierstofurtheroptimizecelldesignstoincreaseoverallperformance.Theseadvancementshaveenabledustoimprovecostand
performanceofourbatteriesovertime.Forexample,in2015alone,weupgradedthebatteryofourlowestrangeModelSfrom60kWhto70kWh,andourhighest
rangeModelSto90kWh.
Ourengineeringandmanufacturingeffortshavebeenperformedwithalonger-termgoalofbuildingafoundationforfurtherdevelopment.Forinstance,we
havedesignedourbatterypacktopermitflexibilitywithrespecttobatterycellchemistryandformfactor.Insodoing,wecanleveragethesubstantialinvestments
andadvancementsbeingmadegloballybybatterycellmanufacturerstocontinuetoimprovecost.WemaintainextensivetestingandR&Dcapabilitiesatthe
individualcelllevel,thefullbattery-packlevel,andothercriticalbatterypacksystems.Asaresult,wehavebuiltanexpansivebodyofknowledgeonlithium-ion
cellvendors,chemistrytypes,andperformancecharacteristics.Webelievethattheflexibilityofourdesigns,combinedwithourresearchandreal-world
performancedata,willenableustocontinuetoevaluatenewbatterycellsastheybecomecommerciallyviable,andtherebyoptimizebatterypacksystem
performanceandcostforourcurrentandfuturevehicles.
Power Electronics
Thepowerelectronicsinourelectricvehiclepowertraingoverntheflowofhighvoltageelectricalcurrentthroughoutthevehicle.Thepowerelectronics
havetwoprimaryfunctions,poweringourelectricmotortogeneratetorquewhiledrivinganddeliveringenergyintothebatterypackwhilecharging.
Thefirstfunctionisaccomplishedthroughthedriveinverter,whichconvertsdirectcurrent(DC)fromthebatterypackintoalternatingcurrent(AC)todrive
ourinductionmotors.Thedriveinverteralsoprovides“regenerativebraking”functionality,whichcapturesenergyfromthewheelstochargethebatterypackwhen
needed.Teslahasdevelopedafamilyofdriveinverterdesignsthatarecustomizedtoitsproprietarymotordesignstomostefficientlymeetthedemandsofeachof
ourvehicles.Theprimarytechnologicaladvantagestoourdesignsincludetheabilitytodrivelargeamountsofcurrentinasmallphysicalpackage.
Thesecondfunction,chargingthebatterypack,isaccomplishedbythecharger,whichconvertsalternatingcurrent(usuallyfromawalloutletorother
electricitysource)intodirectcurrentthatcanbeacceptedbythebattery.Teslavehiclescanrechargeonawidevarietyofelectricitysourcesduetothedesignof
thischarger,fromacommonhouseholdoutlettohighpowercircuitsmeantformoreindustrialuses.Inmostmarkets,TeslavehiclescomewithaMobile
Connectorthatallowsformultipledifferentchargingservicestobeused.Inmanymarkets,TeslaoffersaTeslaWallConnectorthatcanbesetuptoprovidehigher
powerchargingthantheMobileConnectors.
Ontheroad,customerscanalsochargeusingourSuperchargernetworkoratavarietyofdestinationsthathavedeployedourchargingequipment.In
addition,ModelSvehiclescanchargeatavarietyofpublicchargingstationsaroundtheworld,eithernativelyorthroughasuiteofadapters.Thisflexibilityin
chargingprovidescustomerswithadditionalmobility,whilealsoallowingthemtoconvenientlychargethevehicleovernightathome.
Dual Motor Powertrain
InOctoberof2014,welaunchedtheinitialversionofourdualmotorpowertrain,whichusestwoelectricmotorstoprovidegreaterefficiency,performance,
andrangeinanall-wheeldriveconfiguration.Conventionalall-wheeldrivevehiclesdistributepowertothewheelsfromasingleenginedrivingacomplex
mechanicaltransmissionsystem.Bycontrast,Tesla’sdualmotorpowertraindigitallyandindependentlycontrolstorquetothefrontandrearwheels.Thealmost
instantaneousresponseofthemotors,combinedwithlowcentersofgravityprovidesdriverswithcontrolledperformanceandincreasedtractioncontrol.
Vehicle Control and Infotainment Software
Theperformanceandsafetysystemsofourvehiclesandtheirbatterypacksrequiresophisticatedcontrolsoftware.Therearenumerousprocessorsinour
vehiclestocontrolthesefunctions,andwewritecustomfirmwareformanyoftheseprocessors.Theflowofelectricitybetweenthebatterypackandthemotor
mustbetightlycontrolledinordertodelivertheperformanceandbehaviorexpectedinthevehicle.Forexample,softwarealgorithmsenablethevehicletomimic
the“creep”feelingwhichdriversexpectfromaninternalcombustionenginevehiclewithouthavingtoapplypressureontheaccelerator.Similaralgorithmscontrol
traction,vehiclestabilityandthesustainedaccelerationandregenerativebrakingofthevehicle.Softwarealsoisusedextensivelytomonitorthechargestateof
eachofthecellsofthebatterypackandtomanageallofitssafetysystems.Driversusetheinformationandcontrolsystemsinourvehiclestooptimize
performance,customizevehiclebehavior,managechargingmodesandtimesandcontrolallinfotainmentfunctions.Wedevelopalmostallofthissoftware,
includingmostoftheuserinterfaces,internally.
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