A Simulation Approach for Vehicle Life-Time Thermal Analysis Applied to a HEV Battery System 2016-01-0201

In order to meet current and future emission and CO₂ targets, an efficient vehicle thermal management system is one of the key factors in conventional as well as in electrified powertrains. Global vehicle simulation is already a well-established tool to support the vehicle development process.

In contrast to conventional vehicles, electrified powertrains offer an additional challenge to the thermal conditioning: the durability of E-components is not only influenced by temperature peaks but also by the duration and amplitude of temperature swings as well as temperature gradients within the components during their lifetime. Keeping all components always at the preferred lowest temperature level to avoid ageing under any conditions (driving, parking, etc.) will result in very high energy consumption which is in contradiction to the efficiency targets.

The layout of the thermal system and its control strategy need to find a balance of efficiency and component durability under consideration of a representative annual usage profile. In order to support this development process a simulation tool is introduced that allows the assessment of energy consumed for thermal management together with lifetime influence estimations for sensitive components. For lifetime analysis one of the key requirements are short simulation runtimes without sacrificing the model accuracy and fidelity. In the presented approach custom drive cycles are extracted from real-world driving. These drive cycles are a statistically significant representation of real usage behavior. The tool allows assessing the resulting component temperature traces and the energy consumed for conditioning under consideration of different thermal control strategies. This comprehensive approach supports the selection of the system design and its operational control with special respect to aging and energy efficiency already in the early phases of the vehicle development process.