Seite - 18 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 1217 andFordmodels [32]. Reference [32]alsoshoweddifferentmodesof these twosplittingmechanisms andprovideddescriptionsofe-CVTsystemsadoptedbydifferentmanufacturerswhichareshown inFigures23and24. Suchpower-splitHEVsrequire twoelectricmachines,wheels, anengineand aplanetarygear (PG), combiningallof themcanbedone in twenty-fourdifferentways. If another PGisused, thatnumbergetsgreater thanone thousand.Anoptimaldesign incorporatingasingle PGisproposedin[31]. Four-wheeldrive (4WD)configurationscanbenefit fromusingatwo-motor hybridconfigurationas itnullifies theneedofapowertransmissionsystemtothebackwheels (as they get theirownmotor)andprovides theadvantageofenergyreproductionbymeansofregenerative braking[33]. Four-wheeldriveHEVstructure is showninFigure25.Astabilityenhancementscheme forsuchaconfigurationbycontrolling therearmotor is shownin[33]. Figure23. Inputsplit e-CVTsystem.Adaptedfrom[32]. Figure24.Compoundsplit e-CVTsystem.Adaptedfrom[32]. 18