Battery-management-system-原文

BatterymanagementsystemBMSmeansdifferentthingstodifferentpeople.TosomeitissimplyBatteryMonitoring,keepingacheckonthekeyoperationalparametersduringcharginganddischargingsuchasvoltagesandcurrentsandthebatteryinternalandambienttemperature.Themonitoringcircuitswouldnormallyprovideinputstoprotectiondeviceswhichwouldgeneratealarmsordisconnectthebatteryfromtheloadorchargershouldanyoftheparametersbecomeoutoflimits.Forthepowerorplantengineerresponsibleforstandbypowerwho'sbatteryisthelastlineofdefenceagainstapowerblackoutoratelecommunicationsnetworkoutageBMSmeansBatteryManagementSystems.Suchsystemsencompassnotonlythemonitoringandprotectionofthebatterybutalsomethodsforkeepingitreadytodeliverfullpowerwhencalleduponandmethodsforprolongingitslife.Thisincludeseverythingfromcontrollingthechargingregimetoplannedmaintenance.FortheautomotiveengineertheBatteryManagementSystemisacomponentofamuchmorecomplexfastactingEnergyManagementSystemandmustinterfacewithotheronboardsystemssuchasenginemanagement,climatecontrols,communicationsandsafetysystems.TherearethusmanyvarietiesofBMS.DesigningaBMSInordertocontrolbatteryperformanceandsafetyitisnecessarytounderstandwhatneedstobecontrolledandwhyitneedscontrolling.Thisrequiresanindepthunderstandingofthefundamentalcellchemistries,performancecharacteristicsandbatteryfailuremodesparticularlyLithiumbatteryfailures.Thebatterycannotsimplybetreatedasablackbox.BMSBuildingBlocksTherearethreemainobjectivescommontoallBatteryManagementSystemsProtectthecellsorthebatteryfromdamageProlongthelifeofthebatteryMaintainthebatteryinastateinwhichitcanfulfilthefunctionalrequirementsoftheapplicationforwhichitwasspecified.ToachievetheseobjectivestheBMSmayincorporateoneormoreofthefollowingfunctions.(Followthelinkstoseehowthesefunctionsareimplemented.)CellProtectionProtectingthebatteryfromoutoftoleranceoperatingconditionsisfundamentaltoallBMSapplications.InpracticetheBMSmustprovidefullcellprotectiontocoveralmostanyeventuality.Operatingabatteryoutsideofitsspecifieddesignlimitswillinevitablyleadtofailureofthebattery.Apartfromtheinconvenience,thecostofreplacingthebatterycanbeprohibitive.Thisisparticularlytrueforhighvoltageandhighpowerautomotivebatterieswhichmustoperateinhostileenvironmentsandwhichatthesametimearesubjecttoabusebytheuser.ChargecontrolThisisanessentialfeatureofBMS.Morebatteriesaredamagedbyinappropriatechargingthanbyanyothercause.DemandManagementWhilenotdirectlyrelatedtotheoperationofthebatteryitself,demandmanagementreferstotheapplicationinwhichthebatteryisused.Itsobjectiveistominimisethecurrentdrainonthebatterybydesigningpowersavingtechniquesintotheapplicationscircuitryandthusprolongthetimebetweenbatterycharges.SOCDeterminationManyapplicationsrequireaknowledgeoftheStateofCharge(SOC)ofthebatteryoroftheindividualcellsinthebatterychain.Thismaysimplybeforprovidingtheuserwithanindicationofthecapacityleftinthebattery,oritcouldbeneededinacontrolcircuittoensureoptimumcontrolofthechargingprocess.SOHDeterminationTheStateofHealth(SOH)isameasureofabattery'scapabilitytodeliveritsspecifiedoutput.Thisisvitalforassessingthereadinessofemergencypowerequipmentandisanindicatorofwhethermaintenanceactionsareneeded.CellBalancingInmulti-cellbatterychainssmalldifferencesbetweencellsduetoproductiontolerancesoroperatingconditionstendtobemagnifiedwitheachcharge/dischargecycle.Weakercellsbecomeoverstressedduringchargingcausingthemtobecomeevenweaker,untiltheyeventuallyfailcausingprematurefailureofthebattery.Cellbalancingisawayofcompensatingforweakercellsbyequalisingthechargeonallthecellsinthechainandthusextendingbatterylife.History-(LogBookFunction)Monitoringandstoringthebattery'shistoryisanotherpossiblefunctionoftheBMS.ThisisneededinordertoestimatetheStateofHealthofthebattery,butalsotodeterminewhetherithasbeensubjecttoabuse.Parameterssuchasnumberofcycles,maximumandminimumvoltagesandtemperaturesandmaximumcharginganddischargingcurrentscanberecordedforsubsequentevaluation.Thiscanbeanimportanttoolinassessingwarrantyclaims.AuthenticationandIdentificationTheBMSalsoallowsthepossibilitytorecordinformationaboutthecellsuchasthemanufacturer'stypedesignationandthecellchemistrywhichcanfacilitateautomatictestingandthebatchorserialnumberandthedateofmanufacturewhichenablestraceabilityincaseofcellfailures.CommunicationsMostBMSsystemsincorporatesomeformofcommunicationsbetweenthebatteryandthechargerortestequipment.Somehavelinkstoothersystemsinterfacingwiththebatteryformonitoringitsconditionoritshistory.CommunicationsinterfacesarealsoneededtoallowtheuseraccesstothebatteryformodifyingtheBMScontrolparametersorfordiagnosticsandtest.ThefollowingexamplesillustratethreeverydifferentapplicationsofBMSinaction.IntelligentBatterieThelifeofrechargeableNiCadandNickelMetalHydridebatteriessuchasthoseusedinpowertoolscanbeextendedbytheuseofanintelligentchargingsystemwhichfacilitatescommunicationsbetweenthebatteryandthecharger.Thebatteryprovidesinformationaboutitsspecification,itscurrentconditionanditsusagehistorywhichisusedbythechargertodeterminetheoptimumcha