Abstract
Keywords:co-simulation, hybrid vehicle, VeLoDyn, veDYNA, Dymola
In current concepts for hybrid vehicles the main focus is on longitudinal behavior considering fuel consumption, emissions and vehicle performance. But by adding electric motors to the half shafts of a driven axle it is also possible to influence the lateral dynamics thus gaining advantages in vehicle handling as well. Prior to building a prototype vehicle detailed conceptual investigations have to be conducted in order to identify the optimal powertrain configuration. These investigations are performed by means of dedicated simulation tools. Especially if it comes to hybrid vehicles there is no single tool, which matches all needs for modeling. Furthermore there are different levels of detail in the component models to be considered, depending on the respective application. Different simulation tools have been developed, which specialize on single domains and complexities. In order to describe the overall vehicle behavior accurately enough a problem oriented coupling of several simulation tools is needed. This can be achieved either by co-simulation or by export of component models for integration in one single environment. IAV has developed a flexible solution for a full vehicle simulation based on the modular simulation framework VeLoDyn, which is an in-house developed Simulink based tool, and EXITE ACE for coupling with other simulation tools.
This paper describes the simulation environment for a conceptual investigation of a hybrid powertrain with an active torque-distributing axle differential, which adds torque vectoring functionality to the vehicle. The simulation tools VeLoDyn from IAV, Dymola from Dynasim and veDYNA from TESIS are coupled by means of co-simulation with EXITE ACE from EXTESSY thus resulting in an environment, which allows detailed investigations on both longitudinal and lateral dynamics of the hybrid vehicle.
The basic idea of the new hybrid concept is to integrate two electric machines in the differential casing. This has the advantages that existing engine-transmission configurations can be carried over and the system can be realized as an add-on solution. In case of an automated manual transmission the traction interruption during shifts can be compensated. The potential for energy recuperation is higher compared to other parallel topologies because there are no additional losses between wheel and electric machine in the driveline. Furthermore wheel specific torque vectoring is possible, which gives additional possibilities to influence the lateral dynamics in order to improve handling, self-steering and yaw response.
Based on this hybrid topology the advantages of co-simulation for conceptual investigations are shown. Simulation results of an SUV for both longitudinal and lateral behavior are discussed and an outlook for further developments is given.