22AGV用锂离子电池管理系统的研究与实现

摘要IAGV用锂离子电池管理系统的研究与实现摘要自动导引车(AGV)是一种以电池为动力源，有自动导向系统的无人驾驶运输车。目前AGV主要使用铅酸电池和镉镍电池作电源，铅酸电池的能量密度低，充放电倍率小，寿命短；镉镍电池污染大，需要定期维护。钛酸锂电池具有充放电倍率高，能量密度大，安全性好，循环寿命长，无污染等优点，可以取代铅酸电池和镉镍电池，作为AGV的电源。根据AGV对电源的具体需求开发一套电池管理系统对保证锂电池在使用过程中的安全性及延长电池寿命具有十分重要的意义。本文首先对钛酸锂电池的性能作了深入研究，对钛酸锂电池进行了不同温度段，不同充放电倍率的充放电实验。通过实验分析了温度与电流倍率对电池的充放电效率、开路电压和容量的影响。其次，本文分析了现有荷电状态(SOC)定义的不适应性，重新定义了SOC，用绝对荷电状态，静态荷电状态，动态荷电状态三种定义从不同角度来描绘电池当前的SOC。然后基于扩展卡尔曼滤波算法(EKF)对新定义的电池SOC进行估算，并对算法进行了参数优化及Matlab仿真。仿真结果表明优化后的算法适用于各种工况，SOC估算误差在±3%以内。最后，根据AGV的具体要求，设计开发了BMS的硬件与软件。硬件系统中主芯片采用MC9S12XET256型单片机，采用电池管理专用芯片LTC6802实现对各单体电池的数据采集和被动均衡管理。软件包括上位监控软件和下位嵌入式软件，下位软件采用μC/OSII操作系统来管理应用程序。对所开发的BMS进行了各项性能测试，测试结果表明BMS的各项性能指标都能达到预期值。关键词：自动导引车；电池管理系统；钛酸锂电池；扩展卡尔曼滤波；荷电状态昆明理工大学硕士学位论文IIAbstractIIIResearchandImplementationofLithiumLonBatteryManagementSysteminAGVAbstractAutomatedGuidedVehicle(AGV)isanunmannedcarrier,whichisequippedwithbatteryaspowersourceandautomaticguidancesystem.Atpresent,AGVmainlyuseslead-acidbatteriesandnickel-cadmiumbatteriestosupplypower.Inthecaseoflead-acidbattery,itsenergydensityandthecharge&dischargeratearelow,besides,thebatterylifeisshort.Asforthenickel-cadmiumbattery,itleadstoheavypollution,anditneedsregularmaintenance.Incomparing,thelithiumtitanatebatterieshavese-riousofadvantages,likehighcharge&dischargerate,highenergydensity,bettersecu-rity,longservicelifeformorerecyclingtimesandnopollution,etc.Soitcanreplacelead-acidbatteriesandnickel-cadmiumbatteriestoactasthepoweroftheAGV.Toensurethesafetyofthelithiumtitanatebatteriesduringworkingprocessandextendthebatterylife,itisofgreatsignificancetodevelopaBatteryManagementSystem(BMS)accordingtothetheAGVspecificneeds.Firstofall,anin-depthstudyontheperformancecharacteristicsoflithiumtitanatebatterieshasbeenmadeinthispaper.Aseriesofchargingtestsanddischargingtestshavebeenperformedatvarioustemperaturesanddifferentcharge/dischargecurrents.Throughtheexperiment,theinfluenceoftemperatureandcurrentrateoncertainfacetofthebattery(thechargeanddischargeefficiency,opencircuitvoltage,thecapacity)hasbeenresearched.Second,thenon-adaptabilityoftheexistingStateofCharge(SOC)definitionhasbeenpointedoutandareneweddefinitionofSOChasbeengiven.Itde-pictstheSOCfromadifferentperspectivebyintroducingtheabsolutechargestate,thestaticstateofcharge,thedynamicstateofcharge.ThenweestimatethenewSOCofthebatterywithExtendedKalmanFilter(EKF)algorithm,andhasasimulationofthealgorithmwithMatlabandthenimprovestheEKFalgorithm.Thesimulationresultsshowthattheimprovedalgorithmissuitableforavarietyofconditions,andtheesti-mationerroriswithin±3%.Finally,hardwareandsoftwareoftheBMS,whichcansa-昆明理工大学硕士学位论文IVtisfythespecificrequirementsoftheAGV,hasbeendesigned.ThemainchipinthehardwaresystemisMC9S12XET256microcontroller.ThechipLTC6802isusedtotocollectdataandmanagepassiveequalizationofeachcells.ThesoftwareincludesaPCsoftwaretomonitorBMSandaembeddedsoftwarewhichschedulesapplicationswithμC/OSIIoperatingsystem.Comprehensivetestsoffunctionshadbeenmadeonthede-signedBMS.Ultimately,theresultsshowedthattheperformancesoftheBMSachieveapredeterminedvalue.KeyWords:automatedguidedvehicle;batterymanagementsystem;lithiumtitanatebattery;extendedkalmanfilter;stateofcharge目录I目录摘要.......................................................................................................IABSTRACT................................................................................................III第一章绪论...............................................................................................11.1课题背景及来源.........................................................................11.2电池管理系统发展现状.............................................................21.2.1SOC估算技术现状...........................................................21.2.2电池均衡管理现状............................................................51.3AGV电池管理系统技术方案分析............................................61.3.1AGV对电池的要求...........................................................71.3.2锂电池类型选择................................................................71.3.3电池组具体配置................................................................81.3.4SOC估算算法及均衡方法的选择....................................81.4本文研究内容.............................................................................9第二章钛酸锂电池性能研究.................................................................112.1锂电池概述...............................................................................112.1.1锂电池工作原理..............................................................112.1.2锂电池充放电方式..........................................................122.1.3锂电池主要性能指标......................................................122.1.4本文相关概念定义..........................................................132.2钛酸锂电池充放电实验...........................................................142.2.1实验电池说明..................................................................142.2.2实验仪器..........................................................................152.2.3实验目的..........................................................................172.2.4实验方