Page - 277 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 437 PHEV(candidate#16)doesnotuse theEV#2andseriesmodewithoutconsiderationof thedrivetrain loss,evenif it can implement theEV#2andseriesmode. This isbecause these twooperatingmodes cannotprovide theminimumfuel consumption for thegivendrivingcondition. Instead, theEV#1, powersplitandparallelmodewereusedwiththeoperationtimesof283s,27s,and365s, respectively, across the total driving timeof 765 s (Figure 13c). On theother hand,when thedrivetrain loss is considered,ascanbeseenfromFigure13b,c, theEV#2modeisusedat lowwheelpower (less than 8kW)andhighvehicle speed (72–95kph). Theoperation timeof theEV#2mode is79s,while the EV#1,powersplit, andparallelmodesareusedfor110s,30s,and456s, respectively. It isnotedthat theseriesmodewasnotused,evenwhendrivetrain losswasconsidered. Fromthecomparativeanalysis, itwas foundthat themodeselectionandoperationtimeofeach modevariesdependingonthepresenceorabsenceofdrivetrain loss. This isbecause thedrivetrain lossaffects thesystemefficiency for thegivendrivingconditions. Asaresult, adifferentoperating modewasselectedandadifferentmodeoperationtimewasobtained,which leads toadifferent fuel economy.Whenthedrivetrain loss isnotconsidered, the fueleconomywasobtainedas28.76km/L, andwhenthedrivetrain loss is taken intoconsideration, the fueleconomyisdecreasedbyasmuchas 8.1%to26.43km/L. It is seenfromthecomparativeanalysis forcandidate#16 that thedrivetrain loss hasasignificant impactonthefueleconomy,whichdemonstrates that thedrivetrain lossshouldbe considered in fueleconomyevaluations. (a) (b) Candidate #16 (HWFET) Operation Time (s) Fuel Economy (km/L) EV#1 EV#2 Power Split Parallel Series without drivetrain loss 283 0 27 365 0 28.76 with drivetrain loss 110 79 30 456 0 26.43 (−8.1%) (c) 9HKLFOH VSHHG NSK (9 (9 3RZHU VSOLW 3DUDOOHO 6HULHV (9 3DUDOOHO 9HKLFOH VSHHG NSK (9 (9 3RZHU VSOLW 3DUDOOHO 6HULHV (9 3DUDOOHO (9 Figure13. Comparisonofoptimaloperatingmode for candidate #16 in thepresenceor absenceof drivetrain losses (HWFET). (a)Withoutdrivetrain loss; (b)Withdrivetrain loss; (c)Operation timeand fueleconomy. Now,consideringthedrivetrain loss, the fueleconomiesof theeightcandidates inFigure7were evaluated. InTable4, simulationresultsof theoperationtime, fueleconomy,PEloss,anddrivetrain lossarecomparedfor theHWFETcyclewhenthevehicle isoperated inCSmode. It is seenfromTable4 that the fueleconomiesofcandidates#6and#12weredecreasedcompared withthereference(candidate#1) inspiteof theadditionalmodes. This isbecausebrakedragandpump lossoccurredfromtheadditionalelements,BK1,BK2,andCL1. Thefueleconomiesofcandidates#5, #11, #13, and#16were improvedby3.65%–4.04%,andwefoundthatall thesecandidateshave the parallelmodeincommon. It is seenthat theoperationtimeof theparallelmodeis437–456s,which replacedmostof thepowersplitmodeoperation. Thereasonwhythefueleconomywas improved whenaddingtheparallelmodecanbeexplainedbythereducedPEloss. In theparallelmode,MG1is turnedoffandthere isnopowerflowthroughtheelectricalpath,whichprovidesasmallerPEloss 277