Page - 304 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 997 InthedrivingcycleofNEDC,theequivalentfuelconsumptionper100kmdecreasesfrom7.691L/ 100kmusingthe initialparameters to7.148L/100kmutilizingtheoptimizedparameters. Therefore, the equivalent fuel consumptionusing theoptimized results decreases by7.06%compared to the previous fuel consumption. Figure23showstheengineoperatingpointsbeforeandafteroptimization. Figure23.Engineworkingpointsdistributionbeforeandafteroptimization. As shown in Figure 23, the engine operating points scattering in the areawith low torque (0–60N·m)andhigh fuel consumptionhavedecreased. Furthermore, the engineoperatingpoints scattering inthezonewith lowspeed(1000–1500rpm)andhighfuelconsumptionhavealsodecreased. Hence, theenergymanagementstrategyusingtheoptimizedparametersmakes theengineoperate more in theareawithhightorqueandlowfuelconsumption. By comparing the equivalent fuel consumption per 100 km and the distribution of engine operating points before and after optimization, it can be concluded that the DIRECT algorithm canbeapplied tooptimize thekeyparametersof theenergymanagementstrategyfor theHEVwitha positiveeffect. Theoptimizedresultsobtainedbytheofflinesimulationcanprovideareference for debuggingtherealvehicle. 6.Conclusions (1) In this study, theclosed-loopsimulationmodelof theall-wheel–driveHEVpowertrain isbuilt in Matlab/Simulinkwith thepowercomponentmodelestablishedbasedontheexperimental test. The logic thresholdenergymanagementstrategy iscomprehensivelyanalyzedandformulated. Onthisbasis, thesevenkeyparameters that influence the fueleconomyof theHEV,whichneed tobeoptimized,areextracted. Theaccuracyof thesimulationmodelandvalidityof theproposed logic thresholdenergymanagementstrategyareverifiedbycomparingthesimulationtestand realdrumbenchexperiment. (2) The optimization model of the key parameters based on the fuel economy is proposed. The implementation of theDIRECT algorithm is analyzed. Then, it is applied to solve this nonlinearmultiparameteroptimizationproblemwith theobjectiveofminimizing theequivalent fuel consumption. (3) Theoptimizationresult showsthat the logic thresholdenergymanagementstrategyusingthe optimizedparameters reduces theequivalent fuel consumptionper100kmby7%andmakes engineoperatemoreinthehighefficiencyarea. Thesimulationresultvalidatestheeffectivenessof theDIRECTalgorithminsolving themultiparameterenergyconsumptionoptimizationproblem. Itwillplayaguidingrole incalibratingthecontrol strategyparameters forarealvehicle.Next, 304