New simulation models enable better electric powertrains

November 19, 2015 // By Christoph Hammerschmidt
Simulation of electric powertrains is still a widely uncharted field. The Fraunhofer Institute for Structural Durability and System Reliability LBF is closing the gap with the development of simulation methods and tools – a key technology for the development of electric vehicles.

Electric vehicles are different. What is relevant for the design engineer in this context is that because their powertrain is different, it exhibits different inertia and the vibration behaviour of the entire vehicle is completely different. And because electric vehicles are still a rather new phenomenon in engineering, and the developers do not yet have the same degree of experience as with conventional vehicles. In need are suitable simulation models and prototype tests. Fraunhofer LBF has developed adequate simulation tools and test methods of electric powertrains to enable e-car designers to investigate the vibration behaviour and the resulting operating loads.

The development is part of the e-Generation research project which in the first place is intended to increase the driving range of electric vehicles through lowering their energy consumption. Other goals are reducing manufacturing costs and increase product quality and everyday usefulness. In this context, Fraunhofer LBF has devised and validated various simulation models for a selected powertrain concept. The institute also has carried out the related simulations under the aspect of operational stability and systems reliability.

The resulting multibody simulation models enabled the scientists to tale into account the acceleration as part of the driving dynamics, analyse the vibrations of the entire system against the vehicle’s body and investigate the load on the powertrain bearings. Thus, it was possible to determine systems vibration and loads at higher precision than before.

With the powertrain prototypes, the LBF scientists carried out an experimental characterisation on the test stand. Towards this end, the prototypes have been tested with a test protocol based on real driving manoeuvres and multiple relevant mechanical and electrical signals have been recorded. Using a hardware-in-the-loop (HiL) test environment with real dynamic loads, the scientists were able to take the real vehicle behaviour into account.

The experience gathered during the project is enables Fraunhofer LBF to assist OEMs and suppliers who are developing electric powertrains. The institute can perform