电动汽车电池管理系统模块结构和SOC发展

76IEEETRANSACTIONSONVEHICULARTECHNOLOGY,VOL.60,NO.1,JANUARY2011Battery-ManagementSystem(BMS)andSOCDevelopmentforElectricalVehiclesK.W.E.Cheng,SeniorMember,IEEE,B.P.Divakar,HongjieWu,KaiDing,andHoFaiHoAbstract—Batterymonitoringisvitalformostelectricvehicles(EVs),becausethesafety,operation,andeventhelifeofthepassengerdependsonthebatterysystem.Thisattributeisexactlythemajorfunctionofthebattery-managementsystem(BMS)—tocheckandcontrolthestatusofbatterywithintheirspecifiedsafeoperatingconditions.Inthispaper,atypicalBMSblockdiagramhasbeenproposedusingvariousfunctionalblocks.Thestateofcharge(SOC)estimationhasbeenimplementedusingCoulombcountingandopen-circuitvoltagemethods,therebyeliminatingthelimitationofthestand-aloneCoulombcountingmethod.BymodelingthebatterywithSOCasoneofthestatevariables,SOCcanbeestimated,whichisfurthercorrectedbytheKalmanfil-teringmethod.Thebatteryparametersfromexperimentalresultsareintegratedinthemodel,andsimulationresultsarevalidatedbyexperiment.IndexTerms—Battery-managementsystem(BMS),electricvehicles(EVs),stateofcharge(SOC).NOMENCLATURELi-ionLithiumion.LiFePO4Lithium-ionironphosphate.BMSBattery-managementsystem.EVElectricvehicle.HEVHybridelectricvehicle.OCVOpen-circuitvoltage.CANControlareanetwork.ECUElectroniccontrolunit.EMFElectromotiveforce.SOCStateofcharge.SOHStateofhealth.ManuscriptreceivedJuly31,2009;revisedDecember3,2009,March23,2010,June9,2010,andAugust11,2010;acceptedAugust31,2010.DateofpublicationOctober25,2010;dateofcurrentversionJanuary20,2011.ThisworkwassupportedinpartbytheNicheAreasFundingSchemeoftheHongKongPolytechnicUniversityunderProject1-BB86andbytheAuto-motivePartsandAccessorySystemsR&DCentreLimited,underProjectITP-032-07AP,establishedwithfundingfromtheInnovationandTechnologyFund,HongKong.ThereviewofthispaperwascoordinatedbyMr.D.Diallo.K.W.E.ChengandK.DingarewiththePowerElectronicsResearchCentre,DepartmentofElectricalEngineering,TheHongKongPolytechnicUniversity,Kowloon,HongKong(e-mail:[e-mail];[e-mail]).B.P.DivakariswiththeDepartmentofElectricalandElectronicsEngineer-ing,RevaInstituteofTechnologyandManagement,Bangalore560064,India(e-mail:[e-mail]).H.WuiswiththeNationalEngineeringLaboratoryofAutomotiveElec-tronics,ShanghaiJiaoTongUniversity,Shanghai200240,China(e-mail:[e-mail]).H.F.HoiswiththeDepartmentofElectricalEngineering,TheHongKongPolytechnicUniversity,Kowloon,HongKong(e-mail:[e-mail]).Colorversionsofoneormoreofthefiguresinthispaperareavailableonlineatficients.BExponentialcapacity(Ah)−1.AExponentialvoltage.iCurrent.α,β,andγPolarizationcoefficients.QdDouble-layercapacity(inampere-hours).RnInternalresistance(inohms).IkCurrent(inamperes),whichispositivewhenchargedandnegativewhendischarged[range:(−500∼+500),accordingtothemanufacturer].ΔtSampleperiod(inseconds).QRRatedcapacity(inampere-hours).MMaximumpolarizationvoltage(involts).I.INTRODUCTIONBATTERIESarethemostcommonelectricalenergy-storagedevicesinEVs.Theperformanceofabatterywhenitisconnectedtoaloadorasourceisbasedonthechem-icalreactionsinsidethebattery.Thechemicalsdegradewithtimeandusagethatreflectthegradualreductionintheenergystoragecapacityofthebattery.Thebatterydepreciationprocessneedstobereducedbyconditioningthebatteryinasuitablemannerbycontrollingitscharginganddischargingprofile,evenundervariousloadconditions.Ingeneral,thebatterylifetimewillbediminishedwhenthebatteryisoperatedunderawiderangeofthermalconditionsandfrequentchargeanddeepdischargecycles,particularlyathigh-pulsecurrentconditions.Batteriesaresafe,despitereportsofexplosionorfailure,whenusedwithapower-conditioningsystemthatincorporatessafetyfeaturesandautomaticshutdown[1]–[5].Conventionallow-costbatterychargersemployfewprotectivefeaturesintendedforthatbattery,thuslackingflexibilityandfull-fledgedpro-tection.Hence,BMS,whichisflexibletoprotectbatteriesofdifferenttypesandcanprovideallthesafetyfeatures,hasbeenthetopicofrecentdevelopment/researchinEV[1],[6]–[10]andalternativeenergysystems[6],[7].OneoftheimportantparametersthatarerequiredtoensuresafecharginganddischargingisSOC.SOCisdefinedasthepresentcapacityofthebatteryexpressedintermsofitsratedcapacity[8],[11]–[14].SOCprovidesthecurrentstateofthebatteryandenablesbatteriestosafelybechargedanddis-chargedatalevelsuitableforbatterylifeenhancement.Thus,SOChelpsinthemanagementofbatteries.However,measuringSOCisnotdirect,becauseitinvolvesthemeasurementof0018-9545/$26.00©2010IEEECHENGetal.:BATTERY-MANAGEMENTSYSTEM(BMS)ANDSOCDEVELOPMENTFORELECTRICALVEHICLES77Fig.1.BlockdiagramofBMS.batteryvoltage,current,temperature,andotherinformationthatpertainstothebatteryunderconsideration.AccurateestimationofSOCpreventsbatterydamageorrapidagingbyavoidingunsuitableoverchargeandoverdischarge.TheconventionalSOCestimationusingtheCoulombcount-ingmethodsuffersfromerroraccumulationglitch,leadingtoinaccurateestimation.Inaddition,thefinitebat