Fault Diagnostic System for Cascaded H-Bridge Multilevel Inverter ...

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48 V Cell A5 Cell B5 Cell A4 Cell A3 Cell A2 Cell A1 Cell B4 Cell B3 Cell B2 Cell B1 N 8 Cell C5 Cell C4 Cell C3 Cell C2 Cell C1 A B C + DC - Motor To Charger Charge/ Drive Switch H- Bridge Inverter Cell Figure 1.2. Three-phase wye-connection structure for electric vehicle motor drive and battery charging. 1.3 Faults and their consequences Before continuing discussion in this research, it should be noted that the word fault is used to refer to a semiconductor power switch used in the MLID that fails to operate when provided gate drive signals and includes faults such as short circuit or open circuit. One particular effect on a faulty switch is unbalance output voltage of a MLID. In a balanced MLID system, the three line to neutral output voltages are equal in magnitude and are phase displaced from each other by 120 degree as illustrated in Figure 1.3[8-9].
VCA C C5 C4 C3 C2 120 o C1 A A5 A4 A3 A2 A1 n 120 o 9 120 o B1 VAB Figure 1.3. Balanced output voltage available for 5 cells per phase. On the other hand, if a fault occurs at a semiconductor power switch in a cell, it will cause an unbalanced output voltage; for instance, the MLID system as shown in Figure 1.2 has fault (open or short circuit) on cell 5 at phase B, then the magnitude of line to neutral output voltages of phase B (VBN) are not equal with other phases. This causes the B2 B3 B4 B5 VBC line to line output voltages to also be unbalanced as shown in Figure 1.4 [9]. B
Page 1 and 2: To the Graduate Council: I am submi
Page 3 and 4: Copyright © by Surin Khomfoi All R
Page 5 and 6: ACKNOWLEDGEMENTS There are many peo
Page 7 and 8: ABSTRACT A fault diagnostic and rec
Page 9 and 10: TABLE OF CONTENTS CHAPTER PAGE 1. I
Page 11 and 12: LIST OF FIGURES FIGURE 1.1. SINGLE-
Page 13 and 14: FIGURE 5.21. SIMULATION RESULTS OF
Page 15 and 16: 1. INTRODUCTION 1.1 Background In r
Page 17 and 18: Multilevel inverters provide more p
Page 19 and 20: • Common-mode (CM) voltage: Multi
Page 21: Advantages: • The number of possi
Page 25 and 26: times the level of an unbalanced vo
Page 27 and 28: then, if the probability of a singl
Page 29 and 30: It is possible that AI-based techni
Page 31 and 32: Va n v a2 v a1 A + S A - S B- S A +
Page 33 and 34: 2. SURVEY OF PREVIOUS WORKS 2.1 Int
Page 35 and 36: vehicle. It would be better if one
Page 37 and 38: Several research papers on fault de
Page 39 and 40: technology would reduce the impleme
Page 41 and 42: The vector in the d-q frame can als
Page 43 and 44: iβ iβ iβ Fault @ S 1 iα phase a
Page 45 and 46: As can be seen in Figure 2.5, the t
Page 47 and 48: Current beta (A) Current beta (A) 1
Page 49 and 50: 2.3.2 Control signal observer appro
Page 51 and 52: Current phase A (A) 25 20 15 10 5 0
Page 53 and 54: As can be seen, two binary bits are
Page 55 and 56: As illustrated in Table 2.4, most d
Page 57 and 58: system or training a neural network
Page 59 and 60: Murphy [33] presented a fault diagn
Page 61 and 62: Vdc Vdc Current (A) n 15 10 5 0 -5
Page 63 and 64: 2.4.3 Cascaded H-bridges MLID Fault
Page 65 and 66: 2.5 A promising support for AI-base
Page 67 and 68: waveforms. It is evident that the u
Page 69 and 70: Figure 2.16 (b) shows an example of
Page 71 and 72: technique methodology of fault diag
Page 73 and 74:
3.2 Structure of fault diagnostic s
Page 75 and 76:
The modulation index (ma) is the ra
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The simulation model is illustrated
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Normal Fault A+ Fault A- Fault B+ F
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(a) (c) Figure 3.8. Experiment of o
Page 83 and 84:
3.4 Feature extraction system Simul
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Normal Fault A+ Fault A- Fault B+ F
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X1 X2 X3 X4 X5 Xn Data PCA Scores t
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Selecting a reduced subset (PCs kep
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The collected data from both simula
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Score PC1 Score PC1 -2 -4 -6 4 6 4
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population created from multiple in
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• Encoded input PCs: the PCs to b
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andomly selects a crossover point w
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Loadings on PC#13 Scores on PC#13 L
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3.6 Neural network classification A
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As a comparison among transformatio
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Reselect training set Table 3.2. Ta
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[42], is used to simulate the targe
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The second category of testing resu
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4. RECONFIGURATION TECHNIQUE 4.1 In
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4.3 Reconfiguration method The reco
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Amplitude (pu.) 1 0.8 0.6 0.4 0.2 0
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traction motor only at half load co
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% Relative to fundamental component
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Van Vbn Vcn Vab Vbc Vca 100 0 -100
Page 125 and 126:
4.5 Summary The reconfiguration tec
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5.2 Fault Diagnostic technique for
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will be trained with short circuit
Page 131 and 132:
5.2.3 Principal component selection
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5.3 Simulation validation Several S
Page 135 and 136:
The principal component analysis (P
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1 p{1} a{1} Input 1 p{1} Subsystem
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INV_A INV_B INV_C Showing the sub-s
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Fault creating circuit RT-LAB comma
Page 143 and 144:
Figure 5.13. Obviously, the loss of
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For the short circuit validation, t
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Starting current Fault start (a) Fa
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As can be seen, the simulation and
Page 151 and 152:
Loss of gate drive signal fault Rea
Page 153 and 154:
Starting current Fault start Fault
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Fault start Fault clear Fault start
Page 157 and 158:
Table 5.3. Performance investigatio
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5mV/1A (2A/Div) Real open circuit f
Page 161 and 162:
The Opal-RT system needs a few cycl
Page 163 and 164:
6. CONCLUSIONS AND RECOMMENDATIONS
Page 165 and 166:
their locations. Also, a genetic al
Page 167 and 168:
6.2 Contributions This dissertation
Page 169 and 170:
technique for tracking the current
Page 171 and 172:
• S. Khomfoi, L. M. Tolbert, “A
Page 173 and 174:
Chapter 1 [1] L. M. Tolbert, F. Z.
Page 175 and 176:
Characteristics,” IEEE Transactio
Page 177 and 178:
[28] S. Nandi, H. A. Toliyat, X. Li
Page 179 and 180:
[43] D. Zhang, H. Li, “A Low Cost
Page 181 and 182:
[58] J. Fieres, A. Grubl, S. Philip
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Fault Diagnostic System for Cascaded H-Bridge Multilevel Inverter ...

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