TY  - THES
U1  - Bachelor Thesis
A1  - Becherer, Julian
T1  - Conceptual design of a battery management system for the UWC Modular Battery System with focus on an advanced state of charge estimation
N2  - The objective of this thesis is the conceptual design of a battery management system for the first prototype of the UWC (University of the Western Cape) Modular Battery System. The battery system is a lithium-ion battery that aims to be used in renewable energy systems and for niche electric vehicles such as golf carts.

The concept that is introduced in this thesis comprises the parameter monitoring, the safety management and has its main focus on an accurate state of charge estimation. 
Another battery system that was already implemented is used as base for the parameter monitoring and the safety management for the new battery management system. In contrast to that, the concept for the state of charge estimation must be developed completely. 

Different methods for the state of charge estimation which are based on the measured voltage, current and temperature are discussed, evaluated and the chosen method is conceived in this thesis. The method used for the state of charge estimation is different for the time when the battery is active than when it is inactive. During charge and discharge Coulomb counting is used and when the cell is inactive voltage versus state of charge lookup tables are used to update the estimation. 
To have an accurate estimation when the cell is inactive only for a short time, a model of the voltage relaxation is used to predict the voltage when the cells are in equilibrium. This allows the algorithm to reset the state of charge that is estimated by Coulomb counting – which tends to have a growing error over time – frequently.
To evaluate the accuracy of the voltage prediction, cell tests were executed where the voltage relaxation was sampled. The recursive least square method to predict the end voltage was tested with a MATLAB programme. With the help of voltage versus state of charge lookup tables it was possible to determine the state of charge accuracy with the accuracy of the voltage prediction.
KW  - Battery Managment System
KW  - Lithium-Ion
KW  - State of Charge
KW  - Battery
Y2  - 2015
U6  - https://nbn-resolving.org/urn:nbn:de:bsz:ofb1-opus4-9356
UN  - https://nbn-resolving.org/urn:nbn:de:bsz:ofb1-opus4-9356
SP  - XII, 65
S1  - XII, 65
ER  -