Page - 293 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2016,9, 997 3.1.2. TorqueDistributionStrategyforDifferentDrivingModes When thevehicle is running, the engineworkingpoints canbe controlled to stay in thehigh efficiencyarea,andthebatterycanbecontrolledtoworkintherangewithinthe lowinternalresistance byadjusting theoutput torquesof the ISGandin-wheelmotors.Manydrivingmodescanbeobtained byvariouscombinationsof theengine, ISGmotor,andin-wheelmotor. (1) Pureelectricdrivingmode Whenstarting, if thevehicle is at lowloadconditionandthebatterycapacity is sufficient, the vehicle isdrivenonlyby the in-wheelmotor, inorder toavoid theengine fromworking in the low efficiencyarea.Whenthemaximumspeedofpureelectricdriving isexceeded, thevehicleswitches intopureenginedrivingmode. (2) Pureenginedrivingmode Whenthevehicleworksatmediumloadcondition, thedemandtorque isprovidedbytheengine only if it canworkintheareaofhighefficiency. If thedemandtorque isgreater thanthemaximum torqueat thehighefficiencyareaor thebatteryneedscharging, the ISGmotoror in-wheelmotorstarts towork,andthevehicleswitches intohybriddrivingmode. (3) Hybriddrivingmode When thevehicle is at high load conditions such as climbingor accelerating, and the engine outputmaximumtorquecannotmeet thedemandtorque, the ISGandin-wheelmotorsprovidepower, if thebatterycapacity is sufficient. Then, thevehicleswitches intohybriddrivingmode. Thehybrid drivingmodecanbesubdivided intoenginedriving+ISGmotorchargingmode,enginedriving+ in-wheelmotordrivingmode,andenginedriving+ISGmotordriving+in-wheelmotordrivingmode. The judgmentconditionandcontrol logic for thedifferentdrivingmodesmentionedabovecan bedisplayedinFigure12. cmdT ISGMotorAsist AllMotorAsistSOCv 0CmdT > NoYes 0V =No Yes lowSOC SOC> Yes No lowSOC SOC> Yes MaxElecVv < No cmd highT Eng> and highSOC SOC> Yes No Yes lowSOC SOC>and highSOC SOC< Yes No Cmd lowT Eng< No Yes lowSOC SOC> Yes No No lowSOC SOC> No =1ISGMotorAssist Yes Yes = 0 AllMotor Assist and Yes = 1AllMotorAssist No No Figure12.Control logicflowforvariousdrivingmodes. 293