Co-Simulation of a BEV Thermal Management System with Focus on Advanced Simulation Methodologies 2023-01-1609

In battery electric vehicles (BEV), thermal management is a key technique to improve efficiency and lifetime. Currently, manufacturers use different cooling concepts with numerous architectures. This work describes the development of a co-simulation framework to optimize BEV thermal management on system level, using advanced simulation methodologies also on component level, merging simulation and testing.

Due to interactions between multiple conditioning circuits, thermal management optimization requires an overall vehicle approach. Thus, a full vehicle co-simulation of a BEV is developed, combining 1D thermal management software KULI and MATLAB/Simulink. Within co-simulation, the precise modeling of vehicle’s subsystems is important to predict thermal behavior and to calculate dynamic heating and cooling demands as well as exchanged energy flows with the thermal management system. Here, different methodologies are applied for cabin and battery modeling and simulation, with this paper primarily focusing on the battery and its cooling system.

Inhomogeneous coolant flow within complex channel geometries complicates the simulation of temperature distribution and heat exchange in the battery, so simulation and testing are merged. The inner cell structures are modeled with detailed thermal networks, followed by scaling and extrapolation methods to estimate the thermal behavior at pack level. In parallel, a novel thermal dummy cell is developed, designed and realized in a hardware prototype, which reproduces heat generation due to electrochemical processes by inner heating elements. Furthermore, the co-simulation is extended to a hardware-in-the-loop (HIL) simulation by coupling battery simulation with thermal dummy cell hardware prototypes on test bench. This configuration enables the validation and correction of simulated thermal behavior and heat flows by measured heat transfer data.