Pop / Bergveld / Danilov Battery Management Systems

Accurate State-of-Charge Indication for Battery-Powered Applications
1. Auflage 2008
ISBN: 978-1-4020-6945-1
Verlag: Springer Netherlands
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, Band 9, 238 Seiten

Reihe: Philips Research Book Series

This book describes the field of State-of-Charge (SoC) indication for rechargeable batteries. An overview of the state-of-the-art of SoC indication methods including available market solutions from leading semiconductor companies is provided. All disciplines are covered, from electrical, chemical, mathematical and measurement engineering to understanding battery behavior. This book will therefore is for persons in engineering and involved in battery management.

Autoren/Hrsg.

Pop, Valer

Bergveld, Henk Jan

Danilov, Dmitry

Regtien, Paul P. L.

Notten, Peter H. L.

Inhaltsverzeichnis

1;Table of contents;7
2;List of abbreviations;10
3;List of symbols;12
4;Chapter 1 Introduction;20
4.1;1.1 Battery Management Systems;20
4.2;1.2 State-of-Charge definition;22
4.3;1.3 Goal and motivation of the research described in this book;23
4.4;1.4 Scope of this book;25
4.5;1.5 References;26
5;Chapter 2 State-of-the-Art of battery State-of-Charge determination;29
5.1;2.1 Introduction;29
5.2;2.2 Battery technology and applications;29
5.3;2.3 History of State-of-Charge indication;34
5.4;2.4 A general State-of-Charge system;41
5.5;2.5 Possible State-of-Charge indication methods;42
5.6;2.6 Commercial State-of-Charge indication systems;56
5.7;2.7 Conclusions;59
5.8;2.8 References;60
6;Chapter 3 A State-of-Charge indication algorithm;64
6.1;3.1 An introduction to the algorithm;64
6.2;3.2 Battery measurements and modelling for the State-of-Charge indication algorithm;64
6.3;3.3 States of the State-of-Charge algorithm;69
6.4;3.4 Main issues of the algorithm;71
6.5;3.5 General remarks on the accuracy of SoC indication systems;76
6.6;3.6 Conclusions;76
6.7;3.7 References;77
7;Chapter 4 Methods for measuring and modelling a battery’s Electro-Motive Force;79
7.1;4.1 EMF measurement;79
7.2;4.2 Voltage prediction;85
7.3;4.3 Hysteresis;99
7.4;4.4 Electro-Motive Force modelling;102
7.5;4.5 Conclusions;109
7.6;4.6 References;109
8;Chapter 5 Methods for measuring and modelling a battery’s overpotential;111
8.1;5.1 Overpotential measurements;111
8.2;5.2 Overpotential modelling and simulation;119
8.3;5.3 Conclusions;124
8.4;5.4 References;125
9;Chapter 6 Battery aging process;126
9.1;6.1 General aspects of battery aging;126
9.2;6.2 EMF measurements as a function of battery aging;129
9.3;6.3 Overpotential dependence on battery aging;147
9.4;6.4 Adaptive systems;152
9.5;6.5 Conclusions;156
9.6;6.6 References;157
10;Chapter 7 Measurement results obtained with new SoC algorithms using fresh batteries;159
10.1;7.1 Introduction;159
10.2;7.2 Implementation aspects of the algorithm;160
10.3;7.3 Results obtained with the algorithm using fresh batteries;165
10.4;7.4 Uncertainty analysis;169
10.5;7.5 Improvements in the new SoC algorithm;178
10.6;7.6 Comparison with Texas Instruments’ bq26500 SoC indication IC;188
10.7;7.7 Conclusions;192
10.8;7.8 References;193
11;Chapter 8 Universal State-of-Charge indication for battery-powered applications;195
11.1;8.1 Introduction;195
11.2;8.2 Implementation aspects of the overpotential adaptive system;196
11.3;8.3 SoC=f(EMF) and adaptive system;197
11.4;8.4 Results obtained with the adaptive SoC system using aged adaptive system;199
11.5;8.5 Uncertainty analysis;202
11.6;8.6 Results obtained with other Li-based battery;203
11.7;8.7 Practical implementation aspects of the SoC algorithm;214
11.8;8.8 Conclusions;232
11.9;8.9 References;233
12;Chapter 9 General conclusions;235
12.1;References;237

Leseproben

"Chapter 3

A State-of-Charge indication algorithm (p. 47-48)

As discussed in chapter 2, many advances have been made in State-of- Charge (SoC) indication in recent years, both through continued improvement of the SoC algorithms and through the development of more accurate hardware systems. Nevertheless, there is still no ""ideal"" SoC system that gives accurate indications under all realistic user conditions. The ""ideal"" SoC system is obviously one that is not expensive, can handle all battery chemistries, can operate over a wide range of load currents and can deal with the aging effect. Leading semiconductor companies (e.g. Philips [1]–[3], NXP Research, Texas Instruments [4]–[6], Microchip [7], [8] Maxim [9], [10], etc.) are paying more and more attention to accurate State-of-Charge indication in attempts to find that ideal system.

A SoC algorithm that combines some form of adaptivity with direct measurement and book-keeping systems was developed and implemented by Bergveld et al. in 2000 [1]–[3]. By implementing the mathematical models described in [1], this algorithm was found to be the most sophisticated and accurate [11], [12]. This chapter will give a complete description of this algorithm, which serves as the starting point of this book. This chapter is organised as follows.

An introduction to the algorithm is given in section 3.1. Section 3.2 describes the models and states of the SoC indication system. The main aspects of the algorithm are given in section 3.3. The focus in section 3.4 is on accuracy problems. Section 3.5 presents concluding remarks.

3.1 An introduction to the algorithm

The SoC indication algorithm presented by Bergveld et al. in [1]–[3] aims to eliminate the main drawbacks and combine the advantages of the direct measurement and book-keeping methods described in Chapter 2. The basis of the SoC algorithm is Electro-Motive Force (EMF) measurement during equilibrium and current measurement and integration during charge and discharge. During discharge, in addition to simple Coulomb counting, the effect of the overpotential is also considered [1]. A method has also been developed for updating the value of the maximum capacity for coping with capacity loss due to the aging effect. The algorithm will be described below for a Panasonic CGR17500 Li-ion battery, but the basis of the algorithm holds for other types of Li batteries, too. The rated capacity of this battery is 720 mAh.

3.2 Battery measurements and modelling for the State-of-Charge indication algorithm

The battery model applied in the developed SoC indication algorithm describes the battery EMF and overpotential behaviour, neither of which can be measured directly. The EMF and overpotential curves have been measured with an accurate battery tester and implemented in the Battery Management System (BMS) using mathematical-function approximations [1], [13]. Both the measurement and the implementation method contribute to the final accuracy of the SoC indication.
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