Defining Safety Requirements for Hybrid Electric Vehicles Using System Simulation

During development of road vehicles the definition of safety goals and the design of a corresponding safety concept are essential parts of a requirements engineering process for high quality automotive products. Road vehicles with combustion engine propulsion are well-known and therefore an extended level of experience and know-how exists and can be addressed. Hybrid electric vehicles have been introduced only a couple of years ago with new electric propulsion concepts still being introduced. Therefore, a broad new area of requirements has arisen and still arises. For the review of new safety goals and concepts as well as their impact on subsystems and components it is highly time- and cost- sensitive to determine their effectiveness prior to realisation. We present an example how the use of system simulation is used to define safety requirements of the electric propulsion system in a hybrid electric vehicle. For a given safety concept we focus on one vehicle criteria as described in ECE R100 and DIN EN 1987-2, the unintended movement of the unbraked standing vehicle. The corresponding safety requirement for a vehicle is determined from system simulation. We examine an alternative vehicle for the same criteria and compare results.