Efficient battery system simulations with the Discontinuous Galerkin method applied to the SPMe battery cell model

Sammanfattning

Throughout the past few decades, significant steps have been made towards efficient and accurate simulation of battery cells. Just a few years ago, it was considered state-of-the art to simulate a single battery cell in real-time. These days such simulations are much faster than real-time due to development of new methods and general increase in computational power. While these advances are remarkable, it can still be a significant challenge to go from simulating a single cell to thousands of coupled cells as when simulating a battery system. Such simulations are treated by this thesis, which is done in two ways. First, the Discontinuous Galerkin (DG) method is applied to an electrochemical battery cell model - the Single Particle Model with Electrolyte (SPMe). The application of this method is validated against both analytic solutions and reference simulations. Convergence rates and performance is studied with respect to adaptive time integration, and recommended discretization parameters for the problem is given. Second, the electrical coupling of the battery cells within a battery system is treated with graph-theoretical methods. After first translating the electrical circuit into a graph, a minimum cycle basis is used to derive sufficient equations to resolve Kirchhoff's laws. This yields a large system of equations, which is reduced to a much smaller size by a reduction technique. It is then shown that the performance of the methods can achieve faster than real-time simulations of battery systems with thousands of cells, highlighting the potential of the methods of this thesis.