Seite - 275 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 437 Usingtherecursiveequation,wecanfindtheminimumfuelconsumption, Jk∗; inotherwords, themaximumpotential in the fueleconomyover thewholedrivingschedule [35,36]. 5.ComparativeAnalysisUsingDynamicProgramming PELossandDrivetrainLoss Toevaluate the influenceof thedrivetrain lossesonthe fueleconomy,simulationwasperformed forcandidate#16usingthebackwardsimulator, inwhichthe targetPHEVundergoes thehighway fueleconomytest (HWFET)cycle. In thesimulation, thefinalbatterySOCwasassumedtobeequal to the initial SOC.Asdescribed inSection4, theoperationpointsof theengine,MG1,andMG2were determined,whichguarantee theminimumfuelconsumptionbythedynamicprogrammingresults. Inaddition, theoperatingmodethatprovides theminimumfuelconsumptionwasselected. InFigure11, thesimulationresultsareshown.Theengine torque(b)andspeed(c)werealmost maintainedat theoptimaloperatingpointat80Nmand1600rpm,where theenginehas thehighest thermal efficiency for thedemandedenginepower. TheMG2 torque (b) showedanegativevalue whenregenerativebrakingwasperformed. ThebatterySOC(d)decreasedfromthe initialvaluewhen thevehicleacceleratedandincreasedduringtheregenerativebraking. Thevehiclestarted in theEV#1 modeandusedtheEV#2,powersplit,parallel, andregenerativebrakingmodes (e)duringthedriving. It is seen that theparallelmodewasmostlyused for theHWFETcycle,while the seriesmodewas neverused. (QJLQH 0* 0* [ (QJLQH 0* 0* 7LPH VHF 2 1RGTCVKPI OQFG '8 '8 2QYGT URNKV 2CTCNNGN 5GTKGU 4GIGP D E F G H Figure11.Backwardsimulationresult forcandidate#16consideringPEanddrivetrain loss (highway fuel economy test (HWFET) cycle). (a) Vehicle speed; (b) Torque; (c) Speed; (d) Battery SOC; (e)Operatingmode. 275