Development of Control techniques for Direct AC‐AC Matrix Converter fed Multi

267 Pages·2013·7.19 MB·English

Development of Control techniques for
Direct AC‐AC Matrix Converter fed Multi‐
phase Multi‐motor Drive System

Mohammed Ahmed Saleh
Electrical & Electronics Engineering
College of Engineering & Science
Victoria University, Melbourne, Australia

Submitted in fulfilment of the requirements of the degree of PhD

September 2013
ABSTRACT

There are numerous industrial applications, such as paper mills, locomotive traction, oil
and gas, mining and machine tools, which require high performance control of more
than one electric motor simultaneously. When more than one electric motors are
employed in an electric drive, it is called, ‘multi‐motor drive’. These multi‐motor drives
are generally available in two configurations. The first one consists of a number of
three‐phase voltage source inverters connected in parallel to a common DC link, each
inverter feeding a three‐phase AC motor. This configuration allows independent control
of all machines by means of their own three‐phase voltage source inverters (VSIs).
Nevertheless, this configuration needs n number of voltage source inverters for
supplying n number of AC machines. The second configuration comprises one inverter,
which feeds multiple parallel‐connected three‐phase motors. However, the later
configuration does not allow independent control of each motor and is suitable only for
traction application. The power converter supplying the drive system, are
conventionally, voltage source inverters. However, alternative solution could be a direct
AC‐AC converter that can supply the electric drive system. Exploring this alternative
solution is the subject of this thesis.
Thus for decoupled dynamic control of AC machines working in a group (multi‐motor
drive) is possible by employing multi‐phase (more than three‐phase) motors, where
their stator windings are connected in either series or in parallel and the combination is
supplied from a single multi‐phase power converter.
This thesis explores the control techniques of multi‐phase direct AC‐AC converter for
such specific series and parallel‐connected multi‐phase motor drives. The research
presented here utilises additional degrees of freedom available in a multi‐phase system
to control a number of machines independently. The concept is based on the fact that
independent flux and torque control of any AC machine, regardless of the number of
stator phases requires control of only two stator current components. This leaves the
remaining current components free to control other machines within the group.
The multi‐phase multi‐motor drive system fed using multi‐phase direct AC‐AC
converter need precise Pulse Width Modulation (PWM) technique to independently
control the drive system. The subject of this research is to propose PWM techniques for
such configurations. The thesis focuses on four different cases; five‐phase, six‐phase
(symmetrical and asymmetrical), and seven‐phase system. Five‐phase and six‐phase
drive systems consists of two motors, and seven‐phase drive system controls three
motors. The thesis presents various PWM techniques aimed at these drive
configuration. Carrier‐based, carrier‐based with harmonic injection and direct duty
ratio based PWM techniques are presented in the thesis. The independence of control of
various motors are shown by simulation and experimentation. Although, the proposed
techniques are equally applicable to series‐connected drives and parallel‐connected
drives, the thesis focuses on the former drive configuration. Analytical, simulation and
experimental approach is used throughout the thesis.

i
Declaration

“I, Mohammed Ahmed Saleh, declare that the PhD thesis entitled
“Development of Control techniques for Direct AC-AC Matrix
Converter fed Multi-phase Multi-motor Drive System” is no more
than 100,000 words in length including quotes and exclusive of
tables, figures, appendices, bibliography, references and
footnotes. This thesis contains no material that has been
submitted previously, in whole or in part, for the award of any
other academic degree or diploma. Except where otherwise
indicated, this thesis is my own work”.

Signature Date

ii
ACKNOWLEDGEMENT

The research work presented in this thesis has been carried out under the invaluable
and expert guidance of Professor Akhtar Kalam, Dr. Atif Iqbal and Prof. Haitham Abu-Rub. I
consider it a privilege to have been associated with them for carrying out the research work
towards my PhD degree. I have greatly benefited from their deep insight into the subject and
constant support during numerous fruitful discussions. It is with a deep sense of my affection
and gratitude that I wish to express my sincere thanks to them.
It is my duty to thanks the Head of the Departments, Department of Electrical
Engineering, Qatar University and Department of Electrical & Computer Engineering, Texas
A&M University at Qatar for their help in completing the experimental work at their
laboratory.
My sincere thanks are due to Mr. SK. Moin Ahmed, Research Associate, Department
of Electrical & Computer Engineering, Texas A&M University at Qatar, Qatar, for his
endless support in commissioning the experimental set up used in this work.
I must also acknowledge here the fruitful discussions that I had time and again with
my colleagues, Mr. Moidu Thavot, Mr. Khaleequr Rahman and Mr. Ahmad Anad of Qatar
University, Doha, Qatar.
I also sincerely thanks Qatar Foundation for providing fund for the research work
through the NPRP 4-152-02-053.
I would like to thank my parents, my wife’s parents and my relatives for their moral
support for pursuing this work. Without their constant assurances and assistance, completion
of this project would have not been possible.
Finally, the patience, understanding and co-operation provided throughout the work
by my wife Mona and children Abdullah, Reema and Nour, who had to bear the constraints
of my long working hours during the last three years, are greatly appreciated.

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List of Publications
1. Iqbal, A., Payami, S., Saleh. M., Ahmad, A.A., Moinuddin, S., (2013), “Five-phase
AC/DC/AC converter with PWM rectifier”, Australian journal of Electrical &
Electronics Engineering (Accepted).
2. Saleh, M,Iqbal, A., Ahmed, Sk. M., Abu-Rub. H., Kalam, A., (2013) “Direct Duty ratio
based PWM control of a five-phase Matrix Converter supplying five-phase two-motor
drive system”, Australian Journal of Electrical & Electronics Engg., vol. 9, issue 3, pp.
283-293, Feb. 2013
3. Ahmed, SK.M., Iqbal, A., Abu-Rub, H., Rodriguez, J., Saleh, M., (2011), “Simple
carrier-based PWM technique for a three to nine-phase Matrix Converter”, IEEE Trans.
On Ind. Elect., vol. 58, no. 11, pp. 5014-5023, Nov. 2011.
4. Iqbal, A., Saleh, M., Ahmed, Sk. M., Abu-Rub. H., Kalam, A., (2013) “Simple carrier-
based PWM technique for a three to quasi six-phase Matrix Converter”, Australian
Journal of Electrical & Electronics Engg., vol. 9, issue 3, pp. 295-304, Feb. 2013.
5. Ahmed, M. SK, Iqbal A., Abu-Rub, H., Saleh, M., Kalam. A., (2013), “Vector Control
of a Five-phase induction motor supplied by a Non-square 3X5 phase Matrix
Converter”, Australian Journal of Electrical Engineering, vol. 10, no. 1, March 2013,
pp. 55-63.
6. Saleh, M., Iqbal, A., Thavot, M., Kalam, A., (2013), “Modeling of seven-phase series-
connected three-motor drive system”, 7th IEEE GCC COnf., Doha, Qatar, Nov. 2013
(review).
7. Saleh, M., Khan, M.A., Iqbal, A., Moin, SK., Kalam, A., (2013) “Three to seven phase
Matrix Converter supplied seven-phase three-motor drive”, Journal of Innovation in
Electronics and Communication, vol. 2, Issue 3, pp. 6-13. July-Dec. 2013.
8. Ahmad, R., Iqbal, A., Saleh, M., Kalam, A. (2013), “Performance Analysis of Soft
Starter Based Control of Five-phase Induction Motor”, 2013 IEEE PES General
Meeting, 21 - 25 July 2013, Vancouver, BC, Canada. CD-ROM paper.
9. Islam, S., Bakhs, Ilahi, Iqbal, A., Saleh, M., Kalam, A. (2013), “Stability Analysis of a
Series-Connected Five-phase Induction Motor Drive System using Flux-linkage model”
Paper 4604, 8th IEEE Int. conf. on Industrail electronics and applications, 19-21 June,
2013, Melbourne, Australia, CD-ROM paper.
10. Iqbal, A., Pyami, S., Saleh, M., Anad, A., Kalam, A., (2012), “Analysis of Five-phase
AC/DC/AC active front end converter”, Australian Universities Power Engineering
Conf (AUPEC), 26-29 Sept., Bali, Indonesia, CD-ROM paper.
11. Saleh, M.,Iqbal, A., Moin, SK., Kalam, A., (2012), “Matrix Converter based Five-
phase series-connected induction motor drive”, Australian Universities Power
Engineering Conf (AUPEC), 26-29 Sept., Bali, Indonesia CD-ROM paper.
12. Saleh. M., Iqbal, A., Ahmed, SK.M, Abu-Rub, H., Akhtar, K., (2011), “Carrier-based
PWM technique for a three to six phase Matrix Converter supplying six-phase two-
motor drives”, IEEE IECON, 7-10 Nov, Melbourne, Australia pp. 3347-3352.

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Table of Contents

ABSTRACT ............................................................................................................................ i 
LIST OF FIGURES ............................................................................................................... ix 
LIST OF TABLES ............................................................................................................... xii 
LIST OF ABBREVIATIONS ............................................................................................ xiii 
LIST OF SYMBOLS .......................................................................................................... xiv 
Chapter 1 Introduction ............................................................................................................... 1 
1.1  Preliminary Remark .................................................................................................... 1 
1.2  Power Electronic Converters ....................................................................................... 2 
1.3  Features of Multi-phase Motor Drive .......................................................................... 5 
1.4  Analyzed Drive Topologies ........................................................................................ 6 
1.5  Research Objectives .................................................................................................. 12 
1.6  Layout of the Thesis .................................................................................................. 12 
1.7  Novelty and Contribution of Thesis .......................................................................... 14 
References: ........................................................................................................................... 15 
Chapter 2 Literature Review .................................................................................................... 17 
2.1  Introduction ............................................................................................................... 17 
2.2  Multi-phase Motor Drive Systems ............................................................................ 18 
2.3  Three-phase input and three-phase output Matrix Converter .................................... 22 
2.4  Multi-phase Matrix Converter ................................................................................... 23 
2.5  Summary ................................................................................................................... 28 
References: ........................................................................................................................... 29 
Chapter 3 Over-View of Modelling and Control of three-phase by three-phase Matrix-
Converter.................................................................................................................................. 33 
3.1  Introduction ............................................................................................................... 33 
3.2  Control Algorithms for matrix converter .................................................................. 33 
3.3  MODULATION DUTY CYCLE MATRIXAPPROACH ....................................... 34 
A. Alesina-Venturini 1981 (AV method) ......................................................................... 36 
B. Alesina-Venturini 1989 (Optimum AV method) ......................................................... 37 
3.4  Space Vector Control Approach ............................................................................... 38 
v
A.  SVM Technique ..................................................................................................... 38 
3.7  Carrier-Based PWM Approach ................................................................................. 44 
A. Carrier Based Control Strategy .................................................................................... 44 
B. Application of Offset Duty Ratios ............................................................................... 45 
3.8  Direct Duty Ratio Based PWM approach ................................................................. 47 
3.9  Summary ................................................................................................................... 52 
References: ........................................................................................................................... 52 
Chapter 4 Modelling of Multi-phase Multi-motor Drive System ............................................ 54 
4.1  Introduction ............................................................................................................... 54 
4.2  Modelling of five-phase series-connected two-motor drives .................................... 56 
A.  Modelling of series-connected five-phase two-motor drive ................................. 56 
4.2b  Model in the Rotating Reference Frame ................................................................ 60 
4.2c  Model in the stationary reference frame ................................................................ 63 
4.2d   Simulation Results ............................................................................................. 65 
4.3  Modeling of a Six-phase Series-connected Two-motor Drive System ..................... 66 
4.3a  Phase Variable Model ............................................................................................ 67 
4.3b  Model in the Rotating reference frame .................................................................. 70 
4.3c  Transformation of the model into the stationary common reference frame ......... 72 
4.4   Modelling of A Seven-Phase Series-connected Three-Motor Drive System ............ 74 
4.4a  Phase Variable Model ............................................................................................ 76 
4.4b  Model in the rotating reference frame ............................................................... 83 
4.4 c  Transformation of model in to the stationary common reference frame ........... 91 
Torque equation of the machine become ............................................................................. 93 
4.4d  Simulation Result .................................................................................................. 95 
4.5  Summary ................................................................................................................. 101 
References .......................................................................................................................... 101 
Chapter 5 Space Vector Modelling of Multi-phase Matrix Converter .................................. 104 
5.1  Introduction ............................................................................................................. 104 
5.2  Space Vector Model of a Three-phase to Five-phase Matrix Converter ................. 104 
5.3  Space Vector Model of Three-phase to Six-phase Direct Matrix Converter .......... 127 
5.4  Space Vector Model of Three-phase to Seven-phase Direct Matrix Converter ...... 136 
5.5  Summary ................................................................................................................. 144 
References: ......................................................................................................................... 145 
Chapter 6 Carrier Based PWM Schemes for Feeding Multi-Motor Drive System ............... 146 
vi
6.1  Introduction ............................................................................................................. 146 
6.2  Generalized Carrier-based PWM Techniques for three-to N-phase ....................... 147 
6.2a Application of offset duty ratios ............................................................................. 150 
6.2b Without Common Mode Voltage Addition ............................................................ 152 
6.2.c With Common Mode Voltage Addition ................................................................ 152 
6.2d Output Side over Modulation ................................................................................. 153 
6.2e  Modulator Gain.................................................................................................... 153 
6.3.1  Carrier Based PWM Technique for a Three-to-Five Phase Matrix Converter .... 153 
6.3a Three-To-Five Phase Matrix Converter .................................................................. 154 
6.3b Simulation Results .................................................................................................. 156 
6.3.2  Career Based PWM Technique for a Three-to-Five Phase Matrix Converter for
Supplying Five-phase Two-motor Drives .......................................................................... 157 
6.4a Five-Phase Two-Motor Drive System .................................................................... 158 
6.4b Carrier Based PWM Technique for a two motor system ........................................ 160 
6.4c Simulation Results for RL Load ............................................................................. 162 
6.4d  Simulation Results for Motor Load .................................................................... 166 
6.5  Carrier Based PWM Technique for a Three-to-Six Phase Matrix Converter ......... 170 
6.5a Three-to-Six Phase Matrix Converter system ......................................................... 171 
6.5b Application of Offset Duty Ratio ........................................................................... 172 
6.5c  With Harmonic Injection ..................................................................................... 173 
6.5d  Output Voltage Magnitude .................................................................................. 175 
6.5e Simulation Results .................................................................................................. 175 
6.6  Carrier Based PWM Technique for a Three-to-Six Phase Matrix Converter for
Supplying Six-phase Two-motor Drives ............................................................................ 177 
6.6a Six-Phase Series-Connected Two-Motor Drive Configuration .............................. 178 
6.6b Carrier-Based PWM Technique For Six-Phase Two-Motor Drive ........................ 179 
6.6c Application of Offset Duty Ratio............................................................................ 180 
6.6d Simulation Results .................................................................................................. 182 
6.7  Carrier Based PWM Technique Strategies for a Three-to-Seven Phase Matrix
Converter ............................................................................................................................ 186 
6.7a Application of Offset Duty Ratio............................................................................ 187 
6.7b Without Common-mode voltage addition .............................................................. 189 
6.7b With Common mode voltage Addition .................................................................. 189 
6.7c Simulation Results .................................................................................................. 190 
6.8  Seven-Phase Series Connected Three-Motor Drive System ................................... 193 
6.8a Carrier-Based Pulse Width Modulation Technique ................................................ 194 
6.8b Simulation Results .................................................................................................. 197 
6.8c Independent Control at Identical Frequencies ........................................................ 198 
6.8d Independent Control at Three Different Frequencies ............................................. 201 
6.9  Experimental Investigation ..................................................................................... 203 
6.9a Experimental Set-up ............................................................................................... 203 
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6.9b Experimental Investigation of two motor supply .................................................. 211 
6.9c Experimental investigation on 3x6 phase Matrix Converter .................................. 212 
6.10  Summary ................................................................................................................. 215 
References .......................................................................................................................... 215 
Chapter 7 Direct Duty Ratio Based Pulse Width Modulation of Multi-phase Matrix Converter
................................................................................................................................................ 217 
7.1  Introduction ............................................................................................................. 217 
7.2  Direct Duty Ratio based PWM Technique for a Three-phase to n-phase Matrix
Converter for Single-motor drive system ........................................................................... 218 
Case-I: ................................................................................................................................ 218 
7.3  Direct Duty Ratio Based PWM for 3-phase to 5-phase Matrix Converter ............. 223 
7.4  Simulation Results for Five-phase Single-motor Drive .......................................... 226 
7.4  DDPWM of three-to-fivephase Matrix Converters for five-phase two-motor drive
237 
7.5  Simulation Results for Two-motor drive system .................................................... 240 
7.7  Summary ................................................................................................................. 247 
References .......................................................................................................................... 247 
Chapter 8 Conclusions and Future Work ............................................................................... 248 
8.1  Conclusions ............................................................................................................. 248 
8.2  Future Work ......................................................................................................... 252 

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LIST OF FIGURES
Fig. 1.1 General block diagram of a Variable speed drive 2
Fig. 1.2. Possible discrete implementations of a bi-directional switch. 3
Fig. 1.3. Three-phase multi-motor drive system. 7
Fig. 1.4a. Five-phase series-connected two-motor drive structure. 9
Fig. 1.5. Outlay of a three-phase to n-phase direct Matrix Converter. 10
Fig. 2.1. Power Circuit topology of Three-phase to k-phase Matrix Converter. 24
Fig. 2.2. Single-sided Matrix Converter with unidirectional power switches as shown in
reference [2.58]. 27
Fig. 2.3. Indirect Matrix Converter with rectifier and inversion stage as shown in reference
[2.58]. 27
Fig. 3.1. Three phase (input) to single phase (output) basic connection. 34
Fig. 3.2. General topology of three phase to three phase Matrix Converter. 35
Fig. 3.3. Double-sided switching pattern in a cycle period Tp. 37
Fig. 3.4. Direction of the output line-to neutral voltage vectors generated by the active
configurations. 40
Fig. 3.5. Double-sided switching pattern in a cycle period Tp [3.7]. 44
Fig. 3.6. Modified offset duty ratios for all input phases. 46
Fig. 3.7. Output and Switching pattern for kth phase in the Case I. 50
Fig. 3.8. Output and Switching pattern for kth phase in the Case II. 52
Fig. 4.1. Five-phase series-connected two-motor drive structure. 56
Fig. 4.2. Response of Five-phase Two-motor drive supplied by ideal voltage source. 66
Fig. 4.3. Connection diagram for series connection of a six-phase and a three-phase machine.
67
Fig. 4.4. Response of Six-phase Two-motor drive supplied by ideal voltage source. 74
Fig. 4.5. Seven Phase Series-Connected Three-Motor system. 75
Fig. 4.6. Response of Seven-phase Three-motor drive supplied by ideal voltage source. 97
Fig. 4.7, Torque and speed characteristics of Machine 1 97
Fig. 4.8. Torque and Speed characteristics of Machine 2. 98
Fig. 4.9. Speed and Torque Characteristics of Machine 3. 98
Fig. 4.10. Current ‘I -I ’. 98
α β
Fig. 4.11. Current ‘Ix -Iy ’. 99
1 1
Fig. 4.12. Source current ‘Ix -Iy ’. 99
2 2
Fig. 4.13. Spectrum of source phase ‘a’ voltage. 99
Fig. 4.14. Spectrum of source voltage Vα. 100
Fig. 4.15. Spectrum of source voltage V . 100
x1
Fig. 4.16. Spectrum of source voltage V . 100
x2
Fig. 5.1. Basic topology of a three-phase to five-phase Matrix Converter. 105
Fig. 5.2. Switching states of Group-1. 108
Fig. 5.3. Switching states of Group-2 [4,1,0]. 110
Fig. 5.4. Switching states for Group-4 [3,2,0]. 116
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