Parameter Estimation and Inconsistency Analysis of Lithium Ion Battery Packs in Electric Vehicles

Electric vehicles (EVs) have gained increasing relevance as an environmentally friendly and energy-efficient alternative to traditional liquid or gas fuel vehicles. Lithium-ion battery packs are the primary source of power for EVs. To effectively estimate battery performance and comprehend the electrochemical behaviour of the cell, cell modelling is essential. It aids in boosting the battery’s efficiency and design optimisation. This research work involves the cell modelling and parameter estimation of the lithium-ion battery using MATLAB, with input data obtained from pulse discharge tests. To address the energy and power needs of EVs, several lithium-ion cells are connected in series and parallel configurations. A high fidelity electrical model of a lithium-ion battery pack that incorporates thermal dependence is developed as a part of this study following cell modeling, and the same is utilized for conducting the investigations outlined in this paper. Battery cells in a pack are not identical due to various reasons, leading to non-uniform current, voltage, temperature, and cell characteristics, which can cause faster aging to the pack. The impact of cell-to-cell variations in internal resistance, state of charge (SOC), and capacity on the performance of a lithium-ion battery pack for EV applications are also analysed in this work.