Date of Award

6-27-2022

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Electrical and Computer Engineering

Keywords

BATTERY;BMS;CRLB;EIS;ESTIMATION;THEORETICAL PERFORMANCE ANALYSIS

Supervisor

Balakumar Balasingam

Abstract

Battery parameter estimation using electrochemical impedance spectroscopy (EIS) is a very effective way to explore internal function, nature and properties of a battery. The estimation must be accurate and robust to ensure safe and efficient operation of a battery powered system. In order to maintain reliability, performance-analysis is an indispensable part of the process. The performance analysis, especially the one based on theoretical knowledge, gives an estimate of the expected error in real-world applications. This thesis is focused on developing an approach to theoretically derive the lower bound on the estimation error of battery equivalent circuit model (ECM) parameters. Particularly, the Cramer Rao rower bound (CRLB) is derived in this thesis for the estimation of battery ECM parameters. The CRLB is shown to be a lower bound on the mean square error (MSE) of the estimated parameters. In this thesis, CRLB for two simplified batter ECMs has been derived. The derivation is tested based on data collected from a battery simulator. It is shown that, in the case of linearly observed ECM parameters, the MSE coincides with the CRLB. In the case of non-linearly observed ECM parameters, the CRLB serves as a lower bound on the MSE of the estimated parameters. The approaches presented in this thesis can be useful to further the theoretical analysis of complex battery systems.

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