Page - 126 - in Emerging Technologies for Electric and Hybrid Vehicles

energies Article NewElectro-ThermalBatteryPackModelof anElectricVehicle MuhammedAlhanouti 1,*,MartinGießler 1,ThomasBlank2 andFrankGauterin1 1 InstituteofVehicleSystemTechnology,KarlsruheInstituteofTechnology,Karlsruhe76131,Germany; martin.giessler@kit.edu(M.G.); frank.gauterin@kit.edu(F.G.) 2 InstituteofDataProcessingandElectronics,Eggenstein-Leopoldshafen76344,Germany; thomas.blank@kit.edu * Correspondence:muhammed.alhanouti@partner.kit.edu;Tel.:+49-721-608-45328 AcademicEditor:MichaelGerardPecht Received: 30May2016;Accepted: 12 July2016;Published: 20 July2016 Abstract:Sincetheevolutionoftheelectricandhybridvehicle, theanalysisofbatteries’characteristics andinfluenceondrivingrangehasbecomeessential. This factadvocates thenecessityofaccurate simulationmodelingforbatteries.Differentmodels for theLi-ionbatterycellarereviewedinthis paperandagroupof thehighlydynamicmodels is selected for comparison. Anewopencircuit voltage (OCV)model is proposed. Thenewmodel can simulate theOCVcurves of lithium iron magnesiumphosphate (LiFeMgPO4)battery typeatdifferent temperatures. Italsoconsidersboth charginganddischargingcases. Themost remarkable features fromdifferentmodels, inaddition to theproposedOCVmodel,are integrated inasinglehybridelectricalmodel.Alumpedthermal model is implementedtosimulate the temperaturedevelopment in thebatterycell. Thesynthesized electro-thermalbatterycellmodel isextendedtomodelabatterypackofanactualelectricvehicle. Experimental testsonthebattery,aswellasdrive testsonthevehicleareperformed.Theproposed modeldemonstratesahighermodelingaccuracy, for thebatterypackvoltage, thantheconstituent modelsunderextrememaneuverdrive tests. Keywords: temperatureinfluence;newOCVmodel;batterycircuitmodel; synthesizedbatterymodel; thermalmodel; electricvehicle 1. Introduction Theglobalclimatechange,escalationinfuelcost,andtheenergyconsumption,urgedthenecessity to replace the fossil fuelwith renewableandenvironment friendlyenergysources. Batteryelectric vehicles (BEV)areonemajorapplication,demonstratingthereplacementof fossil fuelbyrenewable energy. Li-ionbatterieshavebecomethepreferableenergystoragefor the futureelectricvehicles [1]. Theyreceivegreaterattentionthanotherbatterytypes, suchas lead-acidandnickel-cadmiumbatteries, due to theirpracticalphysical characteristics. Theyhaveahighspecificenergy, specificpower,power densityandalonglifecycle.Moreover, their self-dischargerate is lowercomparedtoother typesof batteries [1–3]. Figure1demonstratesa typicaldischargecharacteristiccurveofa lithium-ionbattery. Thebattery voltage extendsbetweenanupper and lowervoltage limitsVfull andVcut-off, respectively. Vcut-off represents the empty state of the battery where the minimum allowable voltage is reached. This restriction ismeant toprotect thebattery fromdeepdepletion. ThesectionformedbetweenVfull, Vexp andthecorrespondencescapacityrates (C-rate)0andQexp is identifiedas theexponential region of thedischargecharacteristic curve,atwhich thedischargedvoltagechangesexponentially regarding tothebatterycapacity. ThevoltageholdsanapproximatelysteadyvalueforC-ratesbeyondQexpupto thenominalC-rateQnom,where thenominalVnomvoltage is reached.Notonly is thebatteryvoltage Energies 2016,9, 563;doi:10.3390/en9070563 www.mdpi.com/journal/energies126