Reformulating Parallel-Connected Lithium-Ion Battery Pack Dynamics with Interconnection Resistances as Ordinary Differential Equations

TL;DR

This paper develops analytical solutions for lithium-ion battery pack dynamics with interconnection resistances, transforming complex equations into simpler ODEs to improve simulation, design, and control of parallel-connected battery systems.

Contribution

It introduces a novel analytical approach to model and analyze parallel lithium-ion battery packs considering interconnection resistances, converting DAEs into ODEs.

Findings

Validated model accurately captures effects of interconnection resistances.

Derived conditions for uniform current sharing among cells.

Simplified simulation framework for battery pack analysis.

Abstract

This work presents analytical solutions for the current distribution in lithium-ion battery packs composed of cells connected in parallel, explicitly accounting for the presence of interconnection resistances. These solutions enable the reformulation of the differential-algebraic equations describing the pack dynamics into a set of ordinary differential equations, thereby simplifying simulation and analysis. Conditions under which uniform current sharing across all cells occurs are also derived. The proposed formulation is validated against experimental data and confirms its ability to capture the key behaviours induced by interconnection resistances. These results can support the improved design and control of parallel-connected battery packs.