Abstract

The need to engineer robust electric powertrains for passenger cars and other land vehicles is clear. The design rules that were developed for ICE-driven vehicles no longer apply, yet the market is moving too quickly for similar design rules to be developed through iterative development of electric powertrains. Simulation is the only plausible route forward. ePowertrains are highly integrated, yet the effect of this integration is hard to simulate. At the concept stage the boundary conditions for the design of each sub-system is often poorly defined or over-simplified, and even at the full-system validation/sign-off stage the interaction between the different parts of the system is poorly understood. The reason is that the full powertrain consists of many sub-systems that interact but whose physics require very heterogeneous modelling approaches. The road surface imparts shock loads that pass through the tyres, interacting via the suspension (non-linear kinematics), to the drivetrain (rotating mechanical), electric machine (electro-magnetic), inverter (electrical and control) to the battery (electro-chemical). Interactions are difficult to model with traditional “single-physics” simulation tools. This paper presents a modelling approach that combines all these domains and illustrates various phenomena by means of a representative model of an e-powertrain with realistic properties and loading conditions. The dynamic coupling that exists, not just between adjacent sub-systems but across the full powertrain, is illustrated, providing enormous insight into the behaviour of the full system. All of this is essential for successful system integration. Rather than be a high-end simulation, this approach is achieved using commonly-used simulation tools from well-known sources and can be applied by engineers with generalist skill. This accessibility delivers the democratisation of simulation needed so that the approach can be adopted widely. Furthermore, it is set up to run at an appropriate level of fidelity that produces results in a timely manner. Both of these aspects are necessary if the goals of the e-mobility revolution to be achieved.