Abstract
Passenger Plug-in Hybrid Electric Vehicles (PHEVs) have shown significant fuel reduction potential. Furthermore, PHEVs can also improve longitudinal vehicle dynamics with respect to acceleration and engine elasticity. The objective of this study is to investigate potential of concurrent optimization of fuel efficiency and driving performance. For the studies a backward vehicle model for a parallel PHEV was designed, where the power flow is calculated from the wheels to the propulsion units, the conventional internal combus-tion engine (ICE) and the electric motor/generator (EMG) unit. The hybrid drive train is ac-cording to a P2 layout, consequently the EMG is situated between the shifting clutch and the ICE. The implemented operation strategy distributes the power to both propulsion units de-pending on the vehicle speed, requested driving torque, the battery’s state of charge (SOC) and state of power (SOP). Additional information, such as the slope of the road, can be taken into account by the operation strategy.
In the paper the fuel saving potential as well as the longitudinal dynamics change of different PHEV configurations are presented as a function of battery capacity and EMG power. Conse-quently, applicable hybrid components can be defined. By using additional information of the environment like various sensor data, road slope amongst others, the fuel saving potential can be improved even more. By studying the dynamic model the overall results of the backward model are confirmed. In conclusion, this study shows that it is possible to concurrently reduce fuel consumption and increase driving performance in PHEVs. The potential depends strongly on the configuration of the electric components and the implemented operation strategy. Con-sequently, the hybrid system configuration has to be chosen carefully and aligned to the vehi-cle performance.
KEYWORDS Plug-In Hybrid Electric Vehicles, backward modelling, parallel hybrid, longitudinal vehicle dynamics, fuel efficiency