Seite - 264 - in Emerging Technologies for Electric and Hybrid Vehicles

energies Article DesignMethodologyofaPowerSplitTypePlug-In HybridElectricVehicleConsidering DrivetrainLosses HanhoSon,KyusikPark,SunghoHwangandHyunsooKim* SchoolofMechanicalEngineering,SungkyunkwanUniversity,Suwon-si16419,Korea; hanho1014@naver.com(H.S.); rbtlr9010@naver.com(K.P.);hsh@me.skku.ac.kr (S.H.) * Correspondence: hskim@me.skku.ac.kr;Tel.:+82-31-290-7911 AcademicEditor: Jih-Sheng(Jason)Lai Received: 11 January2017;Accepted: 23March2017;Published: 25March2017 Abstract:Thispaperproposesadesignmethodologyforapowersplit typeplug-inhybridelectric vehicle (PHEV)byconsideringdrivetrain losses. Selectingthe inputsplit typePHEVwithasingle planetarygearas thereference topology, the locationsof theengine,motorandgenerators (MGs), on thespeed leverweredeterminedbyusingthemechanicalpointconsidering thesystemefficiency. Basedon the reference topology, feasible candidateswere selected by considering the operation conditionsof theengine,MG1,andaredundantelement. Toevaluatethefueleconomyoftheselected candidates, the lossmodelsof thepowerelectronic systemanddrivetraincomponentswereobtained fromthemathematicalgoverningequationandtheexperimental results. Basedonthecomponent lossmodel,acomparativeanalysiswasperformedusingadynamicprogrammingapproachunder thepresence or absence of thedrivetrain losses. Itwas found that the selectionof the operating modeandtheoperation timeofeachmodevarysince thedrivetrain lossaffects thesystemefficiency. Inaddition,even if theadditionalmodesprovide theflexibilityof selecting theoperatingmodethat results inahighersystemefficiencyfor thegivendrivingcondition,additionaldrivetrainelements for realizingthemodescandeteriorate the fueleconomydueto theirvarious losses. Keywords:designmethodology;powersplit type;plug-inhybridelectricvehicle (PHEV);drivetrain losses;dynamicprogramming 1. Introduction To meet the regulations for reducing CO2 emissions and increasing the fuel economy, the development of electric drive vehicles such as the battery electric vehicle (BEV) and hybrid electricvehicle (HEV)arean inevitablenecessity. The plug-in hybrid electric vehicle (PHEV) has emerged as a viable solution tomeet these regulations,whileovercomingthedisadvantageof therelativelyshort traveldistanceof theBEV[1]. PHEVcanbedrivenonlyusingelectric energyuntil thebattery stateof charge (SOC)decreases to the lower limit,which is called the ‘AllElectricRange’ (AER)or the ‘chargedepleting (CD)mode’. AfterAER,PHEVhas torunusingthe internal combustionengineandmotor(s) tosustain thebattery SOC,which iscalledthe ‘chargesustaining(CS)mode’. InCSmode,variousoperatingmodessuch asseries,parallel, etc. areuseddependingonthePHEVconfiguration.WhenthePHEVisoperated inCSmode, the fueleconomyisdirectlyrelatedto theoperatingmodes,whicharedeterminedfrom its configuration. The PHEVconfiguration can be classified into series, parallel, andpower-split typeconfigurations [2]. TheToyotahybridsystem(THS) isa typicalexampleof the inputsplit type configuration inwhich the enginepower is split at the input side. TheTHSenables the engine to operate on the optimal operating line (OOL)via the electrically continuousvariable transmission Energies 2017,10, 437;doi:10.3390/en10040437 www.mdpi.com/journal/energies264