High Performance Of Direct Torque Control For Five Phase Induction Machine.

MASTER OF SCIENCE IN ELECTRICAL ENGINEERING

2016

HIGH PERFORMANCE OF DIRECT TORQUE CONTROL

FOR FIVE-PHASE INDUCTION MACHINE

HIGH PERFORMANCE OF DIRECT TORQUE CONTROL FOR FIVE PHASE INDUCTION MACHINE

LOGAN RAJ A/L LOURDES VICTOR RAJ

A thesis submitted

in fulfillment of the requirements for the degree ofMaster of Science in Electrical Engineering

Faculty of Electrical Engineering

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

APPROVAL

I hereby declare that I have read this dissertation/report and in my opinion this dissertation/report is sufficient in terms of scope and quality as a partial fulfillment of Master of Science in Electrical Engineering (Power Electronics and Drives).

Signature : ... Name : ... Date : ...

DECLARATION

I declare that this thesis entitled “High Performance of Direct Torque Control for Five-Phase Induction Machine” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.

Signature : ... Name : ... Date : ...

DEDICATION

To my parents,

supervisor Dr Auzani bin Jidin, and friend Sundram Rahmalingam for their support, care and patience.

ABSTRACT

In recent years, research on multiphase AC drives has received great attention due to its several advantages over three-phase drives such as reducing the amplitude and increasing the frequency of torque pulsations, reducing the rotor harmonic currents, reducing the current per phase without increasing the voltage per phase, and lowering the DC-link current harmonics and higher reliability. Until now, however, neither a circular flux operation nor a decagonal flux operation in formulating an optimal switching strategy has been proposed to achieve high-torque control performance of Direct Torque Control (DTC) of five-phase induction machines. A few previous studies on DTC of five-phase induction machine are limited to analyze the effects of selecting different voltage vectors on torque and flux control performances, which do not facilitate the DTC to obtain fast torque dynamic control, reduced torque ripple and switching frequency. This thesis proposes an optimal switching strategy of DTC of five-phase induction machines for high-performance torque control. By employing a five-phase inverter in the proposed method, it provides a greater number of voltage vectors as compared to that offered in the three-phase inverter which gives more options to select the most optimal voltage vectors. The analysis of effects of selecting different voltage vectors on DTC performances are carried out to identify the most optimal vectors that can be chosen to improve torque control performances for every operating condition. The identification is made with the aid of vector diagrams and some equations which are, equations of torque rate, slip angular frequency and current dynamic. Once the identification is done, all optimal vectors are tabulated into a look up table, and the optimal switching of vectors is accomplished by providing appropriate error status and flux sector into the look up table. The appropriate error status are obtained from the hysteresis comparators which are reponsible to determine proper amplitude of vectors and flux control operations, either to form the flux trajectory into a circular or a decagonal locus. The improvements of the proposed method are verified via simulation and experimental results. The results have shown that the torque ripple and switching frequency in the proposed method are greatly reduced about 50 % and 40 %, respectively from that obtained in the DTC with non-optimal switching strategyof five phase inverter, particularly at low-speed operation. The results have also showed that the proposed DTC with decagonal flux control produces a faster torque dynamic response than the non-optimal switching strategy of five phase inverter DTC. These improvements offered are important features for the electrical drive applications that require high-performance torque control and reduced switching losses or high-efficiency.

ABSTRAK

Sejak kebelakangan ini, kajian tentang pemacu AC berbilang fasa telah menerima perhatian yang tinggi disebabkan oleh banyak kelebihan yang dimilikinya berbanding dengan pemacu tiga fasa seperti pengurangan amplitud dan peningkatan frekuensi bagi denyutan dayakilas, pengurangan harmonik arus angker, pengurangan arus per fasa tanpa peningkatan voltan per fasa, dan pengurangan harmonik arus penghubung-DC dan keboleharapan yang lebih tinggi. Namun begitu, sehingga sekarang, tiada pengoperasian fluks membulat mahupun pengoperasian fluks dekagon dalam memformulasikan sebuah strategi pensuisan optimal dicadangkan untuk mencapai prestasi tinggi kawalan dayakilas bagi Kawalan Dayakilas Langsung (DTC) motor aruhan lima fasa. Segelintir kajian terdahulu tentang DTC motor aruhan lima fasa dihadkan untuk menganalisis kesan-kesan bagi pemilihan vektor voltan yang berlainan terhadap prestasi kawalan dayakilas dan fluks, yang mana tidak menyediakan DTC untuk mendapatkan kepantasan kawalan dayakilas dinamik, pengurangan riak dayakilas dan frekuensi pensuisan. Tesis ini mencadangkan sebuah strategi pensuisan yang optimal bagi pemacu DTC motor aruhan lima fasa untuk prestasi tinggi kawalan dayakilas. Dengan menggunakan sebuah penyongsang lima fasa dalam kaedah cadangan, ia menyediakan bilangan vektor voltan yang lebih banyak berbanding dengan yang ditawarkan dalam pemacu tiga fasa yang memberikan lebih banyak pilihan untuk memilih vektor voltan yang paling optimal. Analisa bagi kesan-kesan pemilihan voltan vektor yang berlainan terhadap prestasi DTC telah dilakukan untuk mengenalpasti voltan vector yang paling optimal yang boleh dipilih untuk menambahbaik prestasi kawalan dayakilas untuk setiap keadaan operasi. Pengenalpastian ini dilakukan dengan bantuan rajah vektor dan beberapa persamaan, iaitu persamaan kadar dayakilas, frekuensi sudut gelinciran dan arus dinamik. Apabila pengenalpastian ini telah dilakukan, kesemua vektor-vektor yang optimal telah dijadualkan ke dalam sebuah jadual carian, dan pensuisan vektor optimal disempurnakan dengan menyediakan status-status ralat yang bersesuaian dan sektor fluks ke dalam jadual carian tersebut. Status-status ralat yang besesuaian diperoleh daripada pembanding-pembanding histeresis yang bertanggungjawab menentukan amplitud vektor yang sesuai dan operasi kawalan fluks, sama ada untuk membentuk trajektori fluks dengan lokus membulat atau dekagon. Penambahbaikan-penambahbaikan bagi kaedah cadangan telah disahkan menerusi keputusan simulasi dan eksperimen. Keputusan tersebut telah menunjukkan bahawa riak dayakilas dan frekuensi pensuisan dengan kaedah cadangan dikurangkan sehingga 50 % dan 40 % daripada yang diperoleh dalam DTC dengan strategi pensuisan yang tidak optimal pemacu lima fasa, terutamanya pada operasi kelajuan rendah. Keputusan juga menunjukkan bahawa DTC cadangan dengan kawalan fluks dekagon menghasilkan sambutan dayakilas dinamik yang lebih cepat berbanding dengan DTC dengan strategi pensuisan yang tidak optimal pemacu lima fasa. Penambahbaikan-penambahbaikan ini merupakan ciri-ciri penting bagi aplikasi pemacuan elektrik yang memerlukan prestasi tinggi kawalan dayakilas dan pengurangan kehilangan pensuisan atau kecekapan yang tinggi.

ACKNOWLEDGEMENTS

I acknowledge, with gratitude, my debt of thanks to Dr. Auzani bin Jidin for his guidance, ancouragement and patience on assisting me throughout my research and towards the completion of this thesis.

I would also like to thank everyone who have contributed to this thesis particularly my friend and co-researcher Sundram Rahmalingam for their undisputed support and encouragament.

This research was fully supported by Universiti Teknikal Malaysia Melaka. I am grateful to this institution for providing me the platform and support through scholarship and sponsorship to complete this study.

Finally, I would like to thank my parents and family members for their moral support encouragement and tollerence throughout my study.

TABLE OF CONTENTS

PAGE DECLARATION

APPROVAL DEDICATION

ABSTRACT i

ABSTRAK ii

ACKNOWLEDGEMENTS iii

TABLE OF CONTENTS iv

LIST OF TABLES vii

LIST OF FIGURES viii

LIST OF APPENDICES xvii

LIST OF SYMBOL xviii

LIST OF ABBREVIATIONS xx

LIST OF ACHIVEMENTS xxii

CHAPTER

1. INTRODUCTION 1

1.1 Research Background 1

1.2 Motivation of Research 5

1.3 Problem statement 5

1.3.1 Large Torque Ripple 6

1.3.2 High Switching Frequency/Losses 6 1.3.3 Slow Torque Dynamic Control 7

1.4 Objectives 7

1.5 Methodology 8

1.6 Contribution of Thesis 11

1.7 Thesis organization 12

2. LITERATURE REVIEW 14

2.1 Introduction 14

2.2 Principle of Direct Torque Control (DTC) of Three-

Phase Induction Motors 14

2.2.1 Mathematical Modelling of Three-phase

Induction Machines. 15

2.2.2 Three-Phase Voltage Source Inverter 18

2.2.3 Control Strategy of DTC 20

2.2.3.1 Control of Flux 20

2.2.3.2 Control of Torque 22

2.2.3.3 Simultaneous Control of Torque and Flux 25 2.2.4 Structure of Direct Torque Control 31 2.3 Principle of Direct Torque Control with Hexagonal

Flux Control for Three-Phase Induction Motors 33 2.3.1 Hexagonal Flux Control based on the Hysteresis

Controllers 33

2.3.2 Hexagonal Flux Control based on the Modification of

Torque Error Status 37

2.3.3 Performance Analysis of Torque Dynamic Control 44 iv

2.4 Direct Torque Control of Five-Phase Induction Motors 48 2.4.1 Comparison of DTC and FOC 49 2.4.2 Conceptual of DTC of Five-Phase Induction Machines 53

2.5 Conclusion 69

3. RESEARCH METHODOLOGY 70

3.1 Introduction 70

3.2 Mapping of Voltage Vectors for Five-Phase Inverter 70 3.2.1 Five-Phase Voltage Source Inverter 71 3.2.2 Space Voltage Vector of Five-phase Voltage 74 3.2.3 d- and q- Components of Stator Voltage 76

3.2.4 Voltage Vectors of Five-phase Inverter on the

Voltage Vector Plane 78

3.3 An Improved Switching Strategy 80

3.3.1 Investigation on Effects of Selecting Different Switching

Voltage Vector Options on Torque Control Behaviour 80 3.3.1.1 Analysis on Torque Dynamic Control using

Torque Rate Equation 81

3.3.1.2 Analysis on Torque Control Capability based on

the Maximum Slip Angular Frequency 83 3.3.1.3 Analysis on Torque Slopes for Various Motor

Operating Conditions 86

3.3.2 Identification of Optimal Voltage Vectors 88 3.3.2.1 Improvement 1: Reduction of Switching Frequency 92 3.3.2.2 Improvement 2: Reduction of Torque Ripple 99 3.3.2.3 Improvement 3: Fast Torque Dynamic Control 105 3.4 Definition of Flux Sectors for Selecting Optimal Vectors 107 3.5 Look-up Table for Selecting Optimal Voltage Vectors 109

3.6 Proposed Control Structure 112

3.7 Simulation Model of DTC of Five-Phase Induction Machine 114 3.7.1 Five-Phase induction machine 117 3.7.2 Simulation Model of Five-Phase inverter 119 3.7.3 Simulation Model of d- and q-Components of Stator Voltage 122 3.7.4 Simulation Model of d- and q-Components of Stator Current 122 3.7.5 Simulation Model of Flux and Torque Estimation for

Five-Phase Induction Machine 123 3.7.6 Simulation Model of Five-Phase Sector Definition 124 3.8 Description on Experimental Setup 127 3.8.1 DS1104 R&D Controller Board 128

3.8.2 FPGA–Altera DE0 Board 129

3.8.3 Hall Effect Current Sensor 132

3.8.4 Gate Drivers 134

3.8.5 Five Phase Voltage Source Inverter 135 3.8.6 Five Phase Induction Machine 135

3.9 Conclusion 137

4. RESULT AND DISCUSSION 138

4.1 Introduction 138

4.2 Performance Analysis of Torque Ripple, Switching Frequency

and Torque Dynamic Control via Simulations 138 4.2.1 Improvement 1: Reduction of Torque Ripple 140 4.2.2 Improvement 2: Minimization of Switching Frequency 147 4.2.3 Improvement 3: Fast Torque Dynamic Control 152 4.3 Verification Improvements via Experimental Results 159 4.3.1 Reduction of Torque Ripple and Switching Frequency 160 4.3.2 Improved Torque Dynamic Control 171

4.4 Conclusion 174

5. CONCLUSION AND RECOMMENDATIONS 175

5.1 Conclusions 175

5.2 Constrains and Limitations of Research 177

5.3 Future Works 178

REFERENCES 181

APPENDICES 193

LIST OF TABLES

TABLE TITLE PAGES

2.1 Selection of Voltage Vectors as Proposed in

(Takahashi and Noguchi, 1986) 30

2.2 Table 2.2 : The look up table proposed in (Toliyat and Huangsheng, 2000) (a) Longgest Voltage Vector

(b) Medium Voltage Vector (c) Shortest Voltage Vector 56

2.3 Stator Flux and Torque Variation for Different Voltage Vectors

for Sector I, as Reported in (Mythili and Thyagarajah, 2005) 58

3.1 Classification of Voltage Vectors of Five-Phase Inverter 78

3.2 Look-up table of DTC with Circular Flux Control

(Optimal Vector Selection) 110

3.3 Look-up table of DTC with Decagonal Flux Control and with

Optimal Vector Switching 111

3.4 Parameters of 5-Phase Induction Machine 136

4.1 Parameters of Five-Phase Induction Motor 139

LIST OF FIGURES

FIGURE TITLE PAGE

1.1 DTC Structure Proposed in (Takahashi and Noguchi, 1986) 2

1.2 Control Structure of DTC of Five-Phase Induction Motor 4

1.3 Flow chart of Research Methodology 10

2.1 Block Diagram of the Mathematical Modelling of an Induction

Machine 17

2.2 A Three-Phase Voltage Source Inverter 19

2.3 Voltage Vectors (including Switching States Information) on the

Voltage Vector Plane 19

2.4 Trajectory of Stator Flux Vector in DTC 21

2.5 A Decoupled Control Structure with a Look-up Table for

Establishing Simultaneous Control of Stator Flux and Torque 26

2.6 Production of Flux Error Status σ_φ and Torque Error Status σ_T using (a) 2-Level Hysteresis Comparator and (b) 3-level Hysteresis

Comparator, Respectively 27

2.7 Typical Waveforms of the Torque, the Torque Error, the Stator Flux, the Flux Error, the Torque Error Status and the Flux Error Status including Voltage Vectors Selection for Controlling the

Stator Flux and Torque in Sector III 29

2.8 Structure of Direct Torque Control (DTC) based Induction

Machine, as Proposed in (Takahashi and Noguchi, 1986) 31

2.9 Structure of Direct Self Control (DSC) based Induction

Machine, as Proposed in (Depenbrock, 1988) 35

2.10 Simulation Result of the Typical Waveforms in Direct Self Control 36

2.11 A Hexagonal Flux Shape obtained in DSC Scheme 37

2.12 Structure of DTC with Inclusion of Modification of Torque Error

Status, as Proposed in (Jidin et al., 2011a) 39

2.13 The Modification Block for Hexagonal Flux Operation 40

2.14 Modified Flux Error Status �_���� _{for Every Sub Sector}

(in Each Sector) for Hexagonal Flux Control 41

2.15 The Shrinking of Hexagonal Flux Locus 42

2.16 Flux Keeps the Increase as it Enters to Sub sector ii Until it

Reaches to the Point c. (i.e. path b-c) with the �_���� = 0 43

2.17 State Diagram of Finite State Machine that Establishes the Modified Flux Error Status for Proper Hexagonal Flux Locus

Operation (as Proposed in (Jidin et al., 2011a)). 44

2.18 Effects of Selecting Different Switching under Dynamic Condition. (a) Stator Voltage Vector in Stator Flux (b) Comparison of the Load Angle, δsr generated by the Same Magnitude of Appropriate

Voltage Vectors. 47

2.19 Structure of Field Oriented Control of Five-Phase Induction

Machine 51

2.20 Structure of Direct Torque Control of Five-Phase Induction

Machine 52

2.21 A Five-Phase Voltage Source Inverter Connected to a Five-Phase

Induction Machine 54

2.22 32 Voltage Vectors (on the voltage vector plane) offered in a

Five-Phase Inverter 54

2.23 Control of Torque is Directly Influenced by the Variation of Angle δsr due to the Irregular Motion of Stator Flux Vector

(e.g. in Sector I). 58

2.24 Hysteresis Comparators for (a) Torque Controller with 7- Level

Hysteresis Band (b) Flux Controller with 2-Level Hysteresis Band 61

2.25 Simulation Results of Torque, Torque Error, Torque Error Status, Stator Currents and Phase Voltage obtained in Five-Phase DTC

(Raj et al., 2013) 62

2.26 Zoomed Images for Simulation Results of Torque and Torque Error as obtained in Fig. 2.24, for (a) Region 1, (b) Region 2

and (c) Region 3. 63

2.27 Simulation Results of Torque, Torque Error, Torque Error Status, Stator Currents and Phase Voltage obtained in Five-

Phase DTC (Raj et al., 2013), at a Sampling Time 50 �s 65

2.28 Zoomed Images for Simulation Results of Torque and Torque Error as obtained in Fig. 2.26, for (a) Region 1, (b) Region 2

and (c) Region 3 66

2.29 Torque Dynamic Control with Selection of Non-Optimal Voltage

Vectors 68

3.1 Simplified Five-Phase Inverter Connected to a Five-Phase

Induction Machine 72

3.2 Simplified Five-Phase Inverter with Consideration only for any

Phase (or �-phase) 73

3.3 Definition of Phase Vectors in (3.4). 75

3.4 Vector Units for Each Phase on the Rectangular Coordinates 77

3.5 32 Voltage Vectors (on the Voltage Vector Plane) offered in a Five- Phase Inverter, as shown in Fig. 2.20 79

3.6 Space Vectors of the Applied Voltage, the Stator Flux and the

Rotor Flux 82

3.7 Phasor Diagrams of Vectors of Stator Voltage, Ohmic Voltage Drop and Back-Emf for (a) Low Speed Operation and (b) Base

Speed Operation 87

3.8 Analysis of Torque Dynamic or Slope based on Current Changes

for Different Switching of Voltage Vectors in Sector III 90

3.9 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (Solid Line) at Low Speed Operations. (a) the Selection of Voltage Vectors and (b) the Variation of Torque

inthe Hysteresis Band 96

3.10 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (Solid Line) at Medium Speed Operations. (a) the Selection of Voltage Vectors and (b) the Variation of

Torque in the Hysteresis Band 97

3.11 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (Solid Line) at High Speed Operations. (a) the Selection of Voltage Vectors and (b) the Variation of

Torque in the Hysteresis Band 98

3.12 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (solid line) at Low Speed Operations. (a) the Torque Waveforms (b) the Torque Error Waveforms, and (c)

the Torque Error Status Waveforms 102

3.13 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (solid line) at Medium Speed Operations. (a) the Torque Waveforms (b) the Torque Error

Waveforms, and (c) the Torque Error Status Waveforms 103

3.14 Control of Torque using the Proposed Method (Dotted Line) and the Conventional DTC (solid line) at High Speed

Operations. (a) the Torque Waveforms (b) the Torque

Error Waveforms, and (c) the Torque Error Status Waveforms 104

3.15 Performance Comparison of Torque Dynamic Control for (a) Conventional DTC with a Circular Flux Operation (b)

Proposed DTC with a Decagonal Flux operation 106

3.16 Flux Sector Definition and Optimal Voltage Vector Selection for

Circular Flux Locus 108

3.17 Flux Sector Definition and Optimal Voltage Vector Selection for

Decagonal Flux Locus 109

3.18 Control structure of the proposed circular flux DTC 113 3.19 Control structure of the proposed decagonal flux DTC 113

3.20 Complete simulation model of proposed circular flux DTC 115 xiii

3.21 Complete simulation model of proposed decagonal flux DTC 116

3.22 Simulation model of 5-Phase induction machine 117 3.23 Detailed simulation model of 5-Phase induction machine 118

3.24 Definition of Phase Voltage and Pole Inverter Voltage (e.g.

in Phase �) based on Simplified Five-Phase Inverter 120 3.25 Simulation Model of Five-Phase Inverter 121

3.26 Simulation Model of �- and �-Component of Voltage 122

3.27 Simulation Model of �- and �-Component of Current 123

3.28 Simulation model of flux and torque estimation 124 3.29 Simulation block of sector definition 124

3.30 Flow chart of sector definition for circular flux 125 3.31 Flow chart of sector definition for decagonal flux 126

3.32 Block diagram of Experimental Setup 127 3.33 Photography of Experimental setup of DTC for 5-Phase Induction

Machine 128

3.34 FPGA Altera DE0 board 130

3.35 Waveform with time delay applied 131

3.36 Current sensor 132

3.37 Schematic diagram of current sensor 133 3.38 Schematic diagram of gate driver 134

3.39 Five-Phase Voltage Source Inverter 135 xiv

3.40 Five Phase Induction Machine 136

4.1 Waveforms of Torque, Stator flux, Phase Stator Currents and Stator Voltage at Low-Speed for (a) the DTC2, and (b) the DTC1 143

4.2 Waveforms of Torque, Stator flux, Phase Stator Currents and Stator Voltage at Medium-Speed for (a) the DTC2, and (b)

the DTC1 144

4.3 Waveforms of Torque, Stator flux, Phase Stator Currents and Stator Voltage at High-Speed for (a) the DTC2, and (b) the DTC1 145

4.4 Mapping of Switching Vectors on the d- and q-Axis Coordinate for (a) the DTC1 at Every Different of Speed Operations, (b) the DTC2at High-Speed, (c) the DTC2 at Medium-Speed, and (d)

the DTC2 at Low-Speed 146

4.5 Comparison of Switching Frequency Performance Resulted in Torque and Currents Waveforms for (a) Low-Speed, (b) Medium-

Speed and (c) High-Speed 151

4.6 Waveforms of Torque, Stator flux and d- and q-Components of Stator Currents when a Step Change of Reference Torque is

Applied, at Low-Speed for (a) DTC1, (b) DTC3, (c) DTC4 155 4.7 Comparison of Torque Dynamic Control Performance, when a Step

Change of Reference Torque is Applied, at Low-Speed for (a)

DTC1, (b) DTC3, and (c) DTC4 156

4.8 Waveforms of Torque, Stator flux and d- and q-Components of Stator Currents when a Step Change of Reference Torque is

Applied, at High-Speed for (a) DTC1 and (b) DTC3 157

4.9 Comparison of Torque Dynamic Control Performance, when a Step Change of Reference Torque is Applied, at High-Speed

for (a) DTC1, and (b) DTC3 158

4.10 Profiles of Current Components when a Step Change of Reference

Torque is Applied, at High-Speed for (a) DTC1, and (b) DTC3 158

4.11 Experimental result of Torque, Stator flux, and Stator Voltage at

Low-Speed for DTC1 and DTC2 (a) Overall, and (b) Zoomed 160 4.12 Experimental Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 162 4.13 Simulation Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 163 4.14 Simulation Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 164

4.15 Experimental Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 167 4.16 Experimental Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 168 4.17 Simulation Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 169

4.18 Simulation Results of Torque, Stator Flux and Stator Voltage at

High -Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 170

4.19 Experimental Results of Torque, Stator Flux and Phase Voltage 172 in DTC1

4.20 Experimental Results of Torque, Stator Flux and Phase Voltage 172

in DTC3

4.21 Comparison of Torque Dynamic Control Performance Between

DTC1and DTC3 173

4.22 Trajectory of Stator Flux (a) Circular Locus in DTC1 and (b)

Decagonal Locus in DTC3 174

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Matlab source code listing 192

B VHDL source code listing 202

LIST OF ABBREVIATIONS

AC - Alternating Current ADC - Analog Digital Converter DAC Digital Analog Converter

DC - Direct current DSC - Direct Self Control DSP - Digital Signal Processor

DT - Sampling period DTC - Direct Torque Control

DTC1 - Conventional DTC of Five Phase Inverter DTC2 - DTC with Optimal Voltage Vector Selection

DTC3 - DTC with Decagonal Flux and Optimal Voltage Vector Selection FPGA - Field Programmer Gate Array

FOC - Field Oriented Control

IGBT - Insulated gate bipolar transistor IM - Induction Motor

LB - Lower band

SVM - Space vector modulated UB - Upper band

3.21 Complete simulation model of proposed decagonal flux DTC 116 3.22 Simulation model of 5-Phase induction machine 117 3.23 Detailed simulation model of 5-Phase induction machine 118 3.24 Definition of Phase Voltage and Pole Inverter Voltage (e.g.

in Phase �) based on Simplified Five-Phase Inverter 120

3.25 Simulation Model of Five-Phase Inverter 121

3.26 Simulation Model of �- and �-Component of Voltage 122 3.27 Simulation Model of �- and �-Component of Current 123 3.28 Simulation model of flux and torque estimation 124

3.29 Simulation block of sector definition 124

3.30 Flow chart of sector definition for circular flux 125 3.31 Flow chart of sector definition for decagonal flux 126

3.32 Block diagram of Experimental Setup 127

3.33 Photography of Experimental setup of DTC for 5-Phase Induction

Machine 128

3.34 FPGA Altera DE0 board 130

3.35 Waveform with time delay applied 131

3.36 Current sensor 132

3.37 Schematic diagram of current sensor 133

3.38 Schematic diagram of gate driver 134

3.39 Five-Phase Voltage Source Inverter 135

3.40 Five Phase Induction Machine 136 4.1 Waveforms of Torque, Stator flux, Phase Stator Currents and Stator

Voltage at Low-Speed for (a) the DTC2, and (b) the DTC1 143 4.2 Waveforms of Torque, Stator flux, Phase Stator Currents and

Stator Voltage at Medium-Speed for (a) the DTC2, and (b)

the DTC1 144

4.3 Waveforms of Torque, Stator flux, Phase Stator Currents and Stator Voltage at High-Speed for (a) the DTC2, and (b) the DTC1 145 4.4 Mapping of Switching Vectors on the d- and q-Axis Coordinate for

(a) the DTC1 at Every Different of Speed Operations, (b) the DTC2at High-Speed, (c) the DTC2 at Medium-Speed, and (d)

the DTC2 at Low-Speed 146

4.5 Comparison of Switching Frequency Performance Resulted in Torque and Currents Waveforms for (a) Low-Speed, (b) Medium-

Speed and (c) High-Speed 151

4.6 Waveforms of Torque, Stator flux and d- and q-Components of Stator Currents when a Step Change of Reference Torque is

Applied, at Low-Speed for (a) DTC1, (b) DTC3, (c) DTC4 155 4.7 Comparison of Torque Dynamic Control Performance, when a Step

Change of Reference Torque is Applied, at Low-Speed for (a)

DTC1, (b) DTC3, and (c) DTC4 156

4.8 Waveforms of Torque, Stator flux and d- and q-Components of Stator Currents when a Step Change of Reference Torque is

Applied, at High-Speed for (a) DTC1 and (b) DTC3 157 4.9 Comparison of Torque Dynamic Control Performance, when

a Step Change of Reference Torque is Applied, at High-Speed

for (a) DTC1, and (b) DTC3 158

4.10 Profiles of Current Components when a Step Change of Reference

Torque is Applied, at High-Speed for (a) DTC1, and (b) DTC3 158 4.11 Experimental result of Torque, Stator flux, and Stator Voltage at

Low-Speed for DTC1 and DTC2 (a) Overall, and (b) Zoomed 160 4.12 Experimental Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 162 4.13 Simulation Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 163 4.14 Simulation Results of Torque, Stator Flux and Stator Voltage

at Low-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 164 4.15 Experimental Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 167 4.16 Experimental Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 168 4.17 Simulation Results of Torque, Stator Flux and Stator Voltage

at High-Speed for DTC1 and DTC2 (a) Overall and (b) Zoomed 169

4.18 Simulation Results of Torque, Stator Flux and Stator Voltage at

High -Speed for DTC1 and DTC3 (a) Overall and (b) Zoomed 170

4.19 Experimental Results of Torque, Stator Flux and Phase Voltage 172 in DTC1

4.20 Experimental Results of Torque, Stator Flux and Phase Voltage 172 in DTC3

4.21 Comparison of Torque Dynamic Control Performance Between

DTC1and DTC3 173

4.22 Trajectory of Stator Flux (a) Circular Locus in DTC1 and (b)

Decagonal Locus in DTC3 174

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Matlab source code listing 192

B VHDL source code listing 202

LIST OF ABBREVIATIONS

AC - Alternating Current ADC - Analog Digital Converter DAC Digital Analog Converter

DC - Direct current DSC - Direct Self Control DSP - Digital Signal Processor

DT - Sampling period DTC - Direct Torque Control

DTC1 - Conventional DTC of Five Phase Inverter DTC2 - DTC with Optimal Voltage Vector Selection

DTC3 - DTC with Decagonal Flux and Optimal Voltage Vector Selection FPGA - Field Programmer Gate Array

FOC - Field Oriented Control

IGBT - Insulated gate bipolar transistor IM - Induction Motor

LB - Lower band

SVM - Space vector modulated UB - Upper band