Abstract
Innovative driveline concepts of electrified vehicles take the vehicle test rigs to their limits. Axlesplit hybrids, for example, have no mechanical connection between their combustion engine powered axle and the electrically powered axle except the road contact (Through-the-road hybrid).
This exceeds the dynamic limits of conventional roller-type dynamometer test rigs. But even under conventional operating conditions, more emphasis on additional test cases should be made: Thermal sensitivity of electrification components and their interconnected thermal management require a refined preconditioning of the test rigs.
Each load point shift by the energetic operating strategy (charge, boost, assist) results in a redistribution of the traction torques of both axles and therefore in a shift of friction saturation and driving stability. Therefore, drive control and chassis control have to act jointly and to be designed commonly. This fact also offers opportunities, like increased regenerative braking up to the control range of the stabilization system, or torque vectoring in the case of single-wheel drive.
By integrated optimization of energetic operating strategy and thermal management of vehicle components, the energy consumption of electrified vehicles can be reduced significantly: Especially plug in hybrids consist of a number of heat sinks and sources, i.e. components that either need to be heated or cooled. These components differ in their optimal temperature range, energy amount and time behavior. For example, the use cases charging, preconditioning, electric drive, warmup and combustion powered drive lead to entirely different system states, which again can depend on drive cycle and climatic conditions
Approaches for reduction of heating or cooling energy are for example
• intelligent connection of fluid circuits
• heat transfer by heat pumps in case of different temperature levels
• heat storage in case of time-delayed energy demand
To take full advantage of electrified drive concepts, in comparison to conventional vehicles enhanced testing concepts and test rigs are needed. Integrated testing approaches are presented which are equally suited for conventional and electrified powertrains.
KEYWORDS – highly dynamic dynamometer test rig, drive control and chassis control, thermal management and preconditioning