Efficient Computational Strategy for Coupled Multi-Physics Battery Pack Simulations

Abstract

Today, most of the battery pack simulations are conducted for design and analysis of the cooling channels to address non-uniform temperature distribution that lead to loss of performance and life. This non-uniformity could lead to different ageing of the cells depending on their location within the pack. This could subsequently trigger undesirable behavior like undercharge or overcharge conditions. In all these simulations, an equivalent circuit model is used to represent electro-chemistry as the detailed model would become computationally expensive. Incorporating degradation and aging mechanisms into these equivalent circuit models are effective for on-board diagnostic devices where time is critical, but a detailed electro-chemical model is necessary to understand balancing of cells in a Li-Ion battery pack. In this paper, we will present an efficient way to simulate battery packs that utilizes high performance computing to demonstrate the importance of detailed electro-chemical model on temperature and potential gradients in a battery pack that lead to cell imbalance. The 3D multi-physics model for the individual Li-Ion pouch cell used to construct the battery pack has been validated earlier with the experimental data at various discharge rates [1]. The battery pack under consideration has modules connected in series. Each module has four cells connected in series and parallel. The Voltage and Temperature profiles of the battery pack with two modules at the end of discharge are shown in Figure 1. Convective cooling boundary condition is imposed on the exterior of the battery pack.