Modeling and Simulation of an Electric Vehicle Lithium-ion Battery Pack Through Bond Graph

Abstract

Due to carbon emissions electric vehicles got popularity over fuel-based vehicles. Lithium-ion batteries are widely used in Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs) as a storage technology because Lithium-ion batteries are significant solutions for storing sustainable energy and especially interesting for green transportation. Since these batteries face limitation of losses in power and energy capabilities at low-temperature operations. Also, voltage instability of the batteries is a cause of power blackout it is needed to enhance voltage stability of batteries. Such models in which thermal dynamics have a big impact on the battery’s performance (in terms of active and passive resistance to output parameters) require the development of complex system equations. The use of Bond Graph (BG) tool becomes effective and simple for attaining system equation of systems which involve both electrical and thermal dynamics. The Lithium-Ion batteries have different electric equivalent models and commonly used models are Thevenin and Second-Order Battery. In this research the Bond graph technique is used to understand and model complete battery packs of Thevenin and Second-Order Battery model of Lithium-Ion batteries considering both electrical and thermal dynamics. Furthermore, state-space equations of electro-thermal battery packs are computed to analyze model dynamics and responses. In the end, models are synthesized with a PID controller in order to improve voltage stability and get stabilized output voltage. Which resulted in obtaining stabilized voltage response and reduced settling time.