Modeling, Stability Analysis and Control of a Direct AC/AC Matrix

360 Pages·2011·9.74 MB·English

AN ABSTRACT OF A THESIS

MODELING, STABILITY ANALYSIS AND CONTROL OF A
DIRECT AC/AC MATRIX CONVERTER BASED SYSTEMS

Melaku Mihret

Master of Science in Electrical and Computer Engineering

The AC-AC matrix converters are pulse-width modulated using either a carrier-
based pulse width modulation (PWM) or space vector modulation techniques. Both
modulation techniques are analyzed for a three phase-to-three phase matrix converter. It
is desirable to be able to synthesize the three-phase voltages with minimum harmonics
and the highest voltage gain possible.

A new methodology for designing an input filter for the matrix converter is
proposed. This approach is based on the Fourier series of the switching signals and
harmonic balance technique. The parameters of the filter are determined based on a
specified maximum allowable source current and input capacitor voltage ripple as well as
the overall system stability.

A complete dynamic modeling and a new approach of steady state analysis for an
AC/AC matrix converter fed induction motor drive are set forth. The dynamic responses
as well as the steady state performance characteristics of the system are studied under
various load conditions while the voltage source operates under a unity power factor.
Similar modeling is also done for a matrix converter feeding a passive RL load.

A new generalized model for stability analysis based on small signal modeling is
proposed for a matrix converter fed induction motor drive system under a constant
Volt/Hertz operation. Different factors which affect the matrix converter stability are
analyzed.

A high performance vector control for a matrix converter fed induction motor
with input power factor control is set forth in this work. Detailed controller designs are
presented after studying the internal and zero dynamics of the overall drive system. The
robustness of the proposed control scheme is verified through computer simulation.

Finally, the actual firing pulses for the bidirectional switches of the matrix
converter are generated using LabVIEW/FPGA on a national instrument NIcRIO chassis.
A computer simulation has been done based on these actual pulses obtained from the
FPGA terminals.
MODELING, STABILITY ANALYSIS AND CONTROL OF A
DIRECT AC/AC MATRIX CONVERTER BASED SYSTEMS

A Thesis
Presented to
The Faculty of the Graduate School
Tennessee Technological University
By
Melaku Mihret

In Partial Fulfillment
Of the Requirements of the Degree
MASTER OF SCIENCE
Electrical Engineering

December 2011
CERTIFICATE OF APPROVAL OF THESIS
MODELING, STABILITY ANALYSIS AND CONTROL OF A
DIRECT AC/AC MATRIX CONVERTER BASED SYSTEMS

By

Melaku Mihret
Graduate Advisory Committee:

Joseph Ojo, Chairperson Date

Ghadir Radman Date

Ahmed Kamal Date

Approved for the Faculty:

Francis Otuonye
Associate Vice President
for Research and Graduate Studies

Date

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DEDICATION

This work is dedicated to my parents
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ACKNOWLEDGEMENTS

I would like my deepest gratitude to the chair person of my advisory committee,
Dr. Joseph Ojo for his expertise guidance, generous support and encouragement during
the course of the research. I would also like to express my sincere thanks to Dr. Ghadir
Radman and Dr. Ahmed Kamal for their effort in reviewing and evaluating my work.
I am grateful to the office of Center for Energy Systems Research (CESR) for the
financial support provided during my graduate study. I would also like to thank ECE
department for creating nice atmosphere and kind treatment with special thanks goes to
Mr. Robert Peterson and Mr Conard Murray for their invaluable support.
I owe my deepest gratitude to Meharegzi Abrham for his time in all the technical
discussions throughout my thesis. And I would also thank him and his wife Elizabeth for
their care and support. I would like to thank Sosthenes, Hossein, Kennedy, Jeff, Mehari
and Will. I am so grateful to my roommates Bijaya, Amrit and Puran for their technical
support and making my stay so cherished.
It is my great pleasure to thank my friends Abebe, Ahmed, Wende and Abel for
their friendship and moral support. I extend my sincere thanks to Dr. Solomon Bekele for
his advice.
My heartfelt appreciation goes toward my families for their unconditional love
and encouragement in all my endeavors.
Lastly, I offer my regards and blessings to all of those who supported me in any
respect during the completion of the work.
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TABLE OF CONTENTS

Page
LIST OF TABLES………….…………………...…………………………………...….xi
LIST OF FIGURES.……..…………………………………………..……………….…xii
CHAPTER 1 ........................................................................................................................1
INTRODUCTION ...............................................................................................................1
1.1 Introduction ...........................................................................................................1
1.2 Overview of Static AC/AC Power Frequency Conversion ...................................1
1.2.1 Indirect Power Frequency Converter ............................................................ 2
1.2.2 Direct AC/AC Converter .............................................................................. 4
1.3 Objectives of the Thesis ........................................................................................6
1.4 Thesis Outline .......................................................................................................7
CHAPTER 2 ......................................................................................................................10
LITERATURE REVIEW ..................................................................................................10
2.1 Modulation Strategies .........................................................................................10
2.2 Input Filter Design ..............................................................................................12
2.3 Stability Analysis of a Matrix Converter System ...............................................14
2.4 Control of Matrix Converter Drive System ........................................................15
CHAPTER 3 ......................................................................................................................19
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Page
MODULATION TECHNIQUES ......................................................................................19
3.1 Introduction .........................................................................................................19
3.2 Carrier Based Modulation ...................................................................................19
3.2.1 Switching Signal Generations ..................................................................... 24
3.3 Space Vector Modulation ....................................................................................26
3.3.1 Direct Space Vector modulation ................................................................. 26
3.3.2 Indirect Space Vector modulation .............................................................. 45
3.3.3 Common Mode Voltage Expression Based on Duty Cycle Space Vector
Modulation ................................................................................................................ 60
3.4 Simulation Results and Discussion .....................................................................75
3.5 Conclusion ..........................................................................................................83
CHAPTER 4 ......................................................................................................................85
INPUT FILTER DESIGN .................................................................................................85
4.1 Introduction .........................................................................................................85
4.2 Fourier Series Analysis of Switching Signals of a Matrix Converter .................86
4.3 Input Filter Parameters Specification ..................................................................97
4.3.1 Harmonic Balance Technique ..................................................................... 99
4.3.2 Stability Analysis for Matrix converter feeding an RL load..................... 106
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Page
4.4 Simulation Results and Discussion ...................................................................111
4.5 Conclusion ........................................................................................................118
CHAPTER 5 ....................................................................................................................119
DYANMIC AND STEADY STATE MODELLING OF MATRIX CONVERTER
SYSTEMS .......................................................................................................................119
5.1 Introduction .......................................................................................................119
5.2 Matrix Converter Feeding an RL Load .............................................................120
5.2.1 Dynamic Modelling .................................................................................. 120
5.2.2 Dynamic Simulation Results and Discussion ........................................... 127
5.2.3 Generalized Steady State Analysis ........................................................... 131
5.2.4 Steady State Simulation Results and Discussions .................................... 136
5.3 Modelling of Matrix Converter Fed Induction Machine ..................................139
5.3.1 Dynamic Modelling .................................................................................. 139
5.3.2 Dynamic Simulation Results and Discussion ........................................... 141
5.3.3 Generalized Steady State Analysis ........................................................... 144
5.3.4 Steady State Simulation Results and Discussions .................................... 147
5.4 Conclusion ........................................................................................................150
CHAPTER 6 ....................................................................................................................151
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Page
6.1 Introduction .......................................................................................................151
6.2 Modeling of the Drive System ..........................................................................152
6.3 Small Signal Analysis .......................................................................................157
6.4 Simulation Results and Discussions .................................................................162
6.5 Steady State Operating Conditions ...................................................................168
6.6 Simulation Result for Volt/Hz Control .............................................................170
6.7 Conclusion ........................................................................................................174
CHAPTER 7 ....................................................................................................................175
VECTOR CONTROL OF MATRIX CONVERTER FED INDUCTION MACHINE ..175
7.1 Introduction .......................................................................................................175
7.2 Field Oriented Control for Matrix Converter Fed Induction Motor with Unity
Input Power Factor Control .........................................................................................176
7.2.1 Indirect Field Oriented Control ................................................................. 176
7.2.2 Unity Input Power Factor Control ............................................................ 181
7.2.3 Input-Output Feedback Linearization ....................................................... 183
7.2.4 Stator Flux Estimation .............................................................................. 202
7.3 Simulation Results and Discussions .................................................................208
7.4 Conclusion ........................................................................................................222
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Page
CHAPTER 8 ....................................................................................................................223
SWITCHING SIGNALS GENERATION IN NI-cRIO CHASIS ...................................223
8.1 Introduction .......................................................................................................223
8.2 Switching signal generation using direct digital synthesis ...............................224
8.2.1 Accumulator .............................................................................................. 225
8.2.2 Lookup Table ............................................................................................ 226
8.3 Conclusion ........................................................................................................232
CHAPTER 9 ....................................................................................................................233
CONCLUSSION AND FUTURE SUGGESTION .........................................................233
9.1 Summary of the Thesis .....................................................................................233
9.2 List of Contributions .........................................................................................236
9.3 Future Work ......................................................................................................237
REFERENCES ................................................................................................................241
APPENDIX A ..................................................................................................................253
APPENDIX B ..................................................................................................................270
APPENDIX C ..................................................................................................................293
APPENDIX D ..................................................................................................................298
APPENDIX E ..................................................................................................................305
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