Page - 303 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 997 Ascanbeobservedfromthebeginning, theequivalent fuelconsumptionper100kmdecreases rapidlywith the increaseof iterationsandfunctionevaluations in thedrivingcycleofNEDC.Then, it stabilizes after 9 iterations or 150 function evaluations. This stabilized value is theminimum equivalent fuelconsumptionper100km.Thecorrespondingparametersare thegloballyoptimized resultsusing theDIRECTalgorithm,whichmeet theminimumequivalent fuel consumption. It shows that the proposed optimizationmethodusing theDIRECT algorithmhas good convergence and effectiveness tooptimize thekeyparametersofenergymanagementstrategyfromtheperspectiveof fueleconomy. Thesimulationof theall-wheel-driveHEVis implementedinthedrivingcycleofNEDC,utilizing the optimized logic threshold control strategy parameters. The simulation results are shown in Figure 22. As can be seen, frequently gear change is avoided. And in the driving condition, the in-wheelmotorsoutputmore torques thanengineand ISGmotor. During thebraking cycle, both in-wheelmotorsandISGmotorworkasgenerators tochargethebattery.AndthebatterySOCchanges fromthe initialvalue0.55 to the terminalvalue0.7. The instantaneous fuel consumption iscontrolled within lowrange inmostof the time. 0 200 400 600 800 1000 1200 1 2 3 4 5 6 7 gear t(s) 0 200 400 600 800 1000 1200 0 50 100 150 200 250 engine output torque t(s) 0 200 400 600 800 1000 1200 -80 -60 -40 -20 0 20 ISG motor output torque t(s) 0 200 400 600 800 1000 1200 -100 -50 0 50 100 150 in-wheel motor output torque t(s) 0 200 400 600 800 1000 1200 45 50 55 60 65 70 75 battery SOC t(s) 0 200 400 600 800 1000 1200 0 1 2 3 4 5 6 instantaneous fuel consumption t(s) Figure22.Simulationresultsofall-wheeldriveHEVmodelutilizingtheoptimizedparameters. 303