Requirement process for the development of new electric drive trains

The profitable and sustainable development of electrified power trains requires a targeted dimensioned drive system with an optimal combination of selected modular components. This requires both, a cohesive system design and the solid coverage of the use of the electrical system by the customer. This consideration is complex due to the strong sensitivity of the components - and thus the drive train - to the operating conditions and the expanded diversity of the customers use and their adaptation to the typical characteristics of the electrical drive trains. As a basis for the development of electrified drive trains therefore a requirement management, as procedural support for time management and integrity, and comprehensive methods for defining/developing requirements proved to be essential. These methods consist of a process for architecture coupled with a process for system design. A stringent requirement management fulfils, concerning the demand of integrity, different challenges. First, it is highly interdisciplinary, i.e. it must cover mechanical, electrical, thermal, magnetic, electronic and chemical aspects. Secondly, the full functionality of the drive train of a complementary system requires software (functions with appropriate application) and hardware. For the definition/development of requirements, first the typical operating conditions of the drive train, which span the design-related operational area, are identified. Based on that, a statistic of the system usage and the correlating boundary condition is derived. This serves as a basis for system and component dimensioning and leads under consideration of the known failure mechanisms in the components to the final system design. The verification of the methodology for deriving requirements is taking place on bases of the actual operation of test fleets, such as The MINI E a BMW supported large-scale experiment. The methodology is illustrated by the example of the new BMW ActiveE.