Date of Award

6-22-2022

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

Keywords

Battery;Electrical Engineering;Electrochemical Impedance spectroscopy

Supervisor

Balakumar Balasingam

Supervisor

Gary Rankin

Abstract

This thesis aims at estimating the parameters of a battery equivalent circuit model (ECM) using electrochemical impedance spectroscopy (EIS). This method has been widely used for analysing state of health of batteries. However, much work hasn’t been done to extract battery ECM parameters using EIS. In this thesis, an approach is offered as a method for obtaining the ECM parameters of a battery using EIS. Also, another approach based on estimation in time domain is developed to estimate the internal resistance of the battery. Further, real world EIS and time-domain data are collected to estimate and compare the ECM parameters using both methods. The experiment is repeated at six different state of charge (SOC) levels of the battery. The analysis showed that at low SOC levels, the experimental results demonstrate a strong solid electrolyte interface (SEI) effect. Furthermore, the experimental data demonstrates that computed ECM parameters using the time-domain technique are very close to those estimated in the frequency domain using EIS data, with a difference of less than 0.01 percent. One major issue that restricts EIS from implementation in real time scenarios is that it is time consuming . EIS experiment takes about 60 minutes to complete. This thesis presents an approach to reduce the EIS data collection time by constructing a new signal where multiple sinewaves are combined to shorten the current signals. This work is done in the simulated environment which showed that shortening the signal increased noise in the output. The algorithms were applied on several signal to noise ratio (SNR) values. Furthermore, simulations demonstrated that at a SNR of 70 EIS time can be reduced to approx. 150 secs.

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