A New MethodofUtilizing Ultra-Capacitor Energy SourcesinHybridElectric VehiclesOver a Wide Speed Range

Inprevious research, theauthors introduced a unique methodtodirectly useanultra-capacitor (UC)without using adc/dc converter asthepeaktraction powersource ofthe (hybrid) electric vehicles. Thatmethodworkswellinurban driving cycles wherethemotorspeedisusually lowerthanhalf ratedspeed. Considerable energyefficiency improvement was achieved comparedtoconventional methodsusinga dc/dc converter astheUC interface. However, theacceleration and braking athigher speeds withonlyultra-capacitor sources still require adc/dc converter. Inthis paper, anewmethodology is proposed todirectly useUC toprovide peakpoweruptothefull vehicle speed. TwoUC charging options arealsoproposed. The overall costreduction comparedtotheprevious methodsis considerable. Detailed simulations verify theeffectiveness ofthe proposed methodology. Labvalidation isongoing.