ANALYSIS AND MODELLING OF ULTRACAPACITOR

NOR AKMAL BINTI RAI

UNIVERSITI TEKNOLOGI MALAYSIA

ANALYSIS AND MODELLING OF ULTRACAPACITOR

NOR AKMAL BINTI RAI

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Electrical – Power)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

JANUARY 2015

iii

Dedicated to my beloved parents

Rai bin Ngah Mat Ali & Rohani binti Jusoh

Siblings

Nor Arina binti Rai

Nor Raidah binti Rai

Muhamad Najmi bin Rai

Muhamad Hisyam bin Rai

and

All my friends in MEP programme

for their support and encouragement

iv

ACKNOWLEDGEMENT

First and foremost, I am very grateful to ALLAH S.W.T. for giving me life and

chance to finish this project without much difficulty. Special thank goes to my helpful

supervisor Dr. Mohd Junaidi bin Abdul Aziz. The supervision and support that he gave

truly helps the progression and smoothness of completing this project. The cooperation

is much indeed appreciated.

Secondly, I would like to express my warmest gratitude to my supportive

lecturer, Dr. Zulkarnain Nordeen who has provided immeasurable support and

guidance toward the completion of my research project.

My grateful thanks also goes to my family for their endless support and

encouragement. My deepest gratitude also extend to all lecturers of University

Teknologi Malaysia (UTM), for their guidance, ideas, and support in completing this

master project. This project had opened my eyes on solving real problems and I was

able to relate them with what I’ve been studied in UTM during the past 1 and half

years.

A number of individuals in Electrical, Chemical and Science faculty were very

helpful and understanding. I would like to acknowledge in particular for their

contribution in this work.

Last but not least, I would like to thank to all my friends for the wise idea and

tips throughout the project works. I’m very much enjoy working with all of you and

thank you very much for all of the contributions and care.

v

ABSTRACT

Ultracapacitor is one of most popular device for energy storage system

because of it capability that have high charge/discharge efficiency, can operate at

high current, have long life cycle and no chemical reaction involve in store and

release of energy. Ultracapacitor modelling is important for the electrical system

analysis and equipment design. An efficient and high accuracy model can help

electrical engineers thoroughly understand ultracapacitor’s characteristics. A

commercial ultracapacitor cell is characterized under standard procedures to assess

its performance. This project focuses on the analysis and modelling of

ultracapacitor cell characteristic. Two experiments involve which are

charging/discharging test and AC Impedance test. The charge / discharge test is to

determine ultracapacitor cell ability on charge and discharge performance. AC

impedance test/ Electrochemical impedance spectroscopy (EIS) is to measure the

complex impedance of ultracapacitor. The purpose of the test is to determine

capacitance and equivalent series resistance. Based on experiment result,

parameters and analysis, the equivalent circuit model of ultracapacitor is proposed.

After that, the proposed model is simulated with MATLAB/Simulink and EIS

Spectrum Analyser for verification. Then, the simulation result carried out is

analysed and compared with experiment results. Based on ultracapacitor

characteristic, the electrical circuit modelling was present in this thesis and can be used

for power electronic, backup memory, heavy transportation application, hybrid electric

vehicles and as power back up for UPS application.

vi

ABSTRAK

Ultracapacitor ialah satu daripada peranti paling popular untuk sistem simpanan tenaga

disebabkan ia mempunyai keupayaan untuk mengecas/menyahcas pada kecekapan

yang tinggi, boleh beroperasi pada arus yang tinggi, mempunyai kitaran umur yang

panjang dan tiada tindak balas kimia terlibat dalam penyimpanan dan pembebasan

tenaga. Model Ultracapacitor penting untuk analisis sistem elektrik dan reka bentuk

peralatan. Kecekapan tinggi dan kejituan model boleh membantu jurutera elektrik

memahami sifat ultracapacitor. Sel ultracapacitor komersial akan digunakan untuk

ujikaji berdasarkan standart prosedur untuk menilai prestasinya. Projek ini

menumpukan kepada analisis dan model sel ultracapacitor. Dua eksperimen terlibat

iaitu ujian mengecas/menyahcas dan ujian arus ulang-alik galangan. Ujian

mengecas/menyahcas adalah untuk menentukan kebolehan prestasi sel ultracapacitor

mengecas/menyahcas. Ujian arus ulang-alik galangan / Elektrokimia Galangan

Spektroskopi adalah untuk mengukur nilai kompleks galangan ultaracapacitor. Tujuan

ujian ialah adalah untuk menentukan nilai rintangan siri setara dan nilai capcitor.

Berdasarkan keputusan eksperimen, parameter dan analisis, model litar elektrik setara

ultracapacitor dicadangkan. Selepas itu, model cadangan disimulasikan dengan

MATLAB / Simulink and EIS Spectrum Analyser untuk pengesahan. Kemudian,

keputusan simulasi yang dijalankan dianalisis dan dibandingkan dengan hasil ujian.

Berdasarkan sifat ultracapacitor melalui ujian yang dijalankan, model litar elektrik

dicadangan didalam tesis ini dan boleh digunakan untuk alatan elektronik kuasa,

aplikasi pengangkutan, kenderaan hibrid elektrik dan aplikasi untuk alat bantuan

ingatan.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiii

LIST OF SYMBOLS xiv

LIST OF APPENDICES xv

1 INTRODUCTION 1

1.1 Overview 1

1.2 Problem Statements 2

1.3 Objectives of Project 2

1.4 Scope and Aim of study 3

1.5 Report Outlines 4

2 LITERATURE REVIEW 5

2.1 Introduction 5

2.2 Ultracapacitor 5

2.3 Structure of ultracapacitor 6

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2.3.1 Electrode 8

2.3.2 Electrolyte 9

2.3.3 Current Collector 10

2.3.4 Separator 10

2.4 Model of Ultracapacitor 11

2.4.1 Basic Ultracapacitor Model 11

2.4.2 Classical Equivalent circuit of

Ultracapacitor 11

2.4.3 Three- Branch Model 13

2.4.4 Model based on Frequency Response 14

2.5 Summary 16

3 METHODOLOGY 17

3.1 Introduction 17

3.2 Ultracapacitor Cell 18

3.3 Charge/Discharge Test 19

3.3.1 Test Circuit 20

3.3.2 Test Equipment 20

3.3.2.1 Power Supply 21

3.3.2.2 Electronic Load 21

3.3.2.3 National Instrument (NI) 22

3.3.3 Test Procedure 23

3.4 AC Impedance Test 24

3.4.1 Test Circuit 24

3.4.2 Test Equipment 25

3.4.2.1Autolab PCSTAT302N 26

3.4.3 Test Procedure 27

3.5 Summary 28

4 RESULT AND DISCUSSION 29

4.1 Introduction 29

4.2 Experiment Result 29

4.2.1 Charge/Discharge Test Result 30

4.2.2 AC Impedance Test Result 31

ix

4.3 Equivalent Electrical Circuit Model of

Ultracapacitor 33

4.4 Equivalent Electrical Circuit Model Simulation 34

4.4.1 Simulation for Charge/Discharge 34

4.4.2 Simulation for AC Impedance 36

4.5 Analysis of Experiment Result and Model

Simulation Result 38

4.6 Limitation during AC Impedance Test 39

5 CONCLUSION 40

5.1 Conclusion of the Project 40

5.2 Suggestions and Recommendations 41

5.3 Future Works 42

REFERENCES 43

Appendix A 46

x

LIST OF TABLES

TABLE NO. TITLE PAGE

3.1 General technical data of Maxwell K2 19

series BCAP3000P270 ultracapacitor cell

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Type of electrochemical energy store [3] 6

2.2 Ultracapacitor physical structure [2] 7

2.3 Electrode layer in Ultracapacitor [5] 9

2.4 Illustration of carbon-carbon symmetrical

Ultracapacitor 11

2.5 Basic ultracapacitor model 12

2.6 Classical Equivalent circuit of ultracapacitor 12

2.7 Three-branch model 13

2.8 Ladder circuit model 14

2.9 Advance equivalent circuit for ultracapacitor 15

2.10 Ultracapacitor model based on temperature,

voltage and frequency behaviour 15

3.1 Maxwell k2 series BCAP3000P270 ultracapacitor cell 18

3.2 Circuit for charge/discharge test 20

3.3 Power supply ELECTRO-AUTOMATIK 21

3.4 Itech IT8514C Electronic load 22

3.5 NI 9219- 24 bit analog input. 22

3.6 Charge/discharge test 23

3.7 AC impedance test circuit 24

3.8 Autolab PGSTAT302N 26

3.9 AC Impedance test of ultracapacitor 27

4.1 Input current and output voltage 30

4.2 Nyquist plot of 3000F Maxwell ultracapacitor 31

4.3 Nyquist plot in MATLAB 33

xii

4.4 Capacitance verses frequency value of ultracapacitor 34

4.5 Equivalent circuit model of ultracapacitor 35

4.6 Simulation Model for charge/discharge 35

4.7 Simulation Model element value of ultracapacitor

for charge/discharge 35

4.8 Simulation result of charge/discharge 36

4.9 Experiment result (nyquist plot) in EIS Spectrum

Analyser 37

4.10 Simulation result and parameter value of simulation

result of AC impedance test 37

4.12 Experiment and simulation result for charge/discharge 38

xiii

LIST OF ABBREVIATIONS

EDLC - Electrical Double Layer Capacitor

AC - Alternating Current

EIS - Electrochemical Impedance Spectroscopy

ESR - Electrical Series Resistance

H2SO4 - Sulphuric Acid

KOH - Potassium Hydroxide/ calcium hydroxide

EPR - Electrical Parallel Resistance

NI - National Instrument

PGSTAT - Potentiostart/Galvanostart

FRA - Frequency Response Analyser

I - Current

V - Voltage

P - Power

UC Ultracapacitor

xiv

LIST OF SYMBOLS

Q - Charge

R - Resistance

L - Inductance

C - Capacitance

Z - Impedance

𝜋 - Pi (3.141593)

f - Frequency

Ω - Ohm

F - Farad

xv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Maxwell k2 series BCAP3000P270 ultracapacitor 44

Cell data sheet

CHAPTER 1

INTRODUCTION

1.1 Overview

Nowadays, ultracapacitor become an alternative and complementary device for

energy storage system. Its ability to fast charge/discharge and long life cycle give an

advantage of ultracapacitor in a lot of electrical and electronic application.

Ultracapacitor also known as supercapacitor or electric double layer capacitor (ELDC)

are one type of an electrochemical device that stores electrical charge in the electrical

double layer surface.

The first electrical device using double layer charge storage was invented in

1957 by H.I. Becker from General Electric. Unfortunately, Becker’s device was not

practical because it is similar to a flooded battery with both electrodes need to immerse

in a container of electrolyte and this device was never been commercialized [1]. As a

rapid development in technology, a lot of researches have been done to produce an

electric double layer capacitor. Varies type of ultracapacitor have been develop based

on its application as electrical energy storages device in power electronic system,

industrial application, heavy transportation application, hybrid electric vehicles, UPS

system and memory backup application.

2

Ultracapacitor have become a popular device in many applications because of

its characteristic that give advantages over other energy storage device. The energy

density of the existing ultracapacitor range is about 1 to 10 Wh/kg and its power

density range typically of 2000 to 20000 W/kg as compared to electrochemical

batteries that have an energy density range about 100 Wh/kg but lower in power

density range 100 to 500W/kg [2]. Furthermore, ultracapacitor have high efficiency,

which can stand at higher current and temperature, have a long life cycle and an

environmental friendly because it’s not involve in any chemical reaction while store

electrical energy as compare to other energy storage device.

1.2 Problem Statement

Ultracapacitor are being used in many applications in electrical and electronic

application, as an energy storage device. Ultracapacitor modelling plays an important

role for the electrical system analysis and equipment design. The ultracapacitor model

can provide detail information and equivalent electrical circuit modelling of energy

storage device. An efficiency and high accuracy model can help electrical engineer to

understand ultracapacitor characteristics.

1.3 Objective

The main objective of this project is:

To study the characteristic of ultracapacitor.

3

To performed in lab testing for ultracapacitor using charge/discharge and AC

Impedance test.

To proposed an equivalent electrical circuit model of tested ultracapacitor.

To simulate equivalent electrical circuit model using MATLAB/Simulink and EIS

Spectrum Analyser.

1.4 Scope and Aim of Study

These projects focus on modelling of ultracapacitor characteristic. This project

needs in lab test and model of the ultracapacitor equivalent circuit. It involves two

parts which are in lab test of ultracapacitor characteristic and modelling of the

ultracapacitor using the equivalent electrical circuit model. There are two types of in

lab test require which is charge/discharge test and AC impedance test. The charge /

discharge test is to determine ultracapacitor cell ability on charge and discharge

performance. AC impedance test/ Electrochemical impedance spectroscopy (EIS) is to

measure the complex impedance of ultracapacitor. Based on experiment result,

parameters and analysis, the equivalent circuit model of ultracapacitor is proposed.

After that, the proposed model is simulated with MATLAB/Simulink and EIS

Spectrum Analyser for verification. Then, the simulation result carried out is analysed

and compared with experimental results.

4

1.5 Report Outlines

The thesisconsists of five chapters. In the first chapter, it discusses the project

background, problem statement, objectives, scope and report outline.

Chapter 2 presents background, characteristic of ultracapacitor, related work

and an overview of ultracapacitor model and parameter identification method. The

principle of ultracapacitor structure and material are explained in detail in this chapter.

In chapter 3, the focus is on detail description for in lab test carried out. It is

clear and concise of work performed. This chapter describes the test circuit and method

used to obtain lab data which will be used to develop ultracapacitor model.

In chapter 4, the lab result and equivalent electrical circuit modelling of

ultracapacitor is attached. This chapter represented in the form of diagrams, waveform

of test result and simulation result of ultracapacitor model. The comparison and

analysis are made in order to achieve objectives. Analysis of data, such as discusses

on the outcome of research in relation to the result are obtained.

Lastly, the conclusion about the project is written on the fifth chapter. It is also

provide suggestions and recommendations for future work.

43

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44

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45

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