Lithium ion battery discharge simulation and experimental verification

Abstract

With the parameter extraction method based on Chen and Rincon-Mora's model, the generic battery model simulation of two dissimilar Lithium-ion batteries is able to partially match the experimental results. Modications such as extra parameters or new parameter extraction methods may be needed to accurately represent the physical discharge behaviour of the Lithium-ion batteries.

Lithium-ion batteries are widely used in many places due to the advantages of their high capacity, energy density, etc. However, battery capacity gradually deteriorates when a Lithium-ion battery is repeatedly cycled through multiples iterations of charge and discharge. The scope of the thesis is to find a battery model to represent dissimilar cells, simulate the discharge behaviour of those cells in parallel and verify the validation of the simulation model with the experimental results.

Chapter 1 introduces some general knowledge of Lithium-ion batteries, including their chemistry principle, advantages and disadvantages, charge and discharge characteristics, etc. Two Lithium-ion battery models developed by Simulink SimPowerSystems, and Min Chen and Gabriel A. Rincon-Mora are presented in Chapter 2 and Chapter 3 respectively. The discharge process of two dissimilar Lithium-ion cells in parallel through a resistive load are simulated using both models. Experiment with the same settings is conducted. The results are compared such that the SimPowerSystems battery model simulation has more discrepancies than Chen and Rincon-Mora's. Chen and Rincon-Mora's model remains to be used in Chapter 4 for battery parameter extraction in order that the extracted parameters can be inserted back into the model for better representation and the simulation of the more precise battery model can be further compared to the experiment on discharging two dissimilar Lithium-ion batteries in parallel through constant-current load.