Seite - 297 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 997 thesimulationandbenchtest, theerrorof theequivalent fuelconsumption is4.5%,which iswithin the generallyallowedrangeof5%. It isnecessary toverify theaccuracyof thevehiclesimulationmodel and the effectivenessof the energymanagement strategy,which canprovideassuranceof thekey parametersoptimizationfor theHEVenergymanagementstrategybasedonofflinesimulation. Table10.Comparisonof results fromofflinesimulationanddrumbenchtest. Parameter OfflineResult DrumBenchTestResult Error SOC 0.7~0.52 0.7~0.56 — Equivalent fuel consumption 7.69L/100km 7.36L/100km 4.5% 5.OptimizationofHEVControlParametersUsingDIRECTAlgorithmBasedonFuelEconomy 5.1. ImplementationofDIRECTAlgorithm TheDIRECTalgorithmisadeterministicglobaloptimizationalgorithmproposedbyJonesetal. in1993 [19]. It isespeciallysuitable foroptimizingamultivariable functionwithspecificvariablesand space [31]. Taketheoptimizationproblemwiththree-dimensionalspaceasanexample; it supposes thatc is thecenterpointof thehypercubeandcalculates thevalueofa function f(x) atpoint c±δei withδequal to1/3of thehypercube length; ei isaunitvector. Theparameter,wi isdefinedas follows: wi=min(f(c+δei), f(c−δei)), (15) It splits thehypercubeintheorderofwi. First, it cuts thehypercubeinthedirectionperpendicular to theminimumvalueofwi. Second, it cuts thehypercube in thedirectionperpendicular toweak minimal value ofwi. Then, it repeats the above steps until the hypercube is cut in all directions. Figure16showsanexampleof thehypercubedivision. 297