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

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v a v b v c v a v b v c Circuit Breaker Fuses Metal oxide varistors Clear fault signal 22 S1 S3 S5 C Motor S 4 Ground fault signal Under/over Voltage signal Protection and Control Over current signal S 6 S 2 Thermal relay Figure 2.2. A typical protection of a conventional voltage-fed inverter drive. Circuit Breaker Intelligent Power Module (IPM ) control unit Speed/current Command Fault indicators S1 S3 S5 C Motor S 4 S Protection Functions 6 Isolated gate driver circuits S 2 - Over current - Over/under voltage -Over temperature Gate drive signals PWM Generator V/Hz Control Law Figure 2.3. A typical protection system of a conventional voltage-fed inverter drive using IPM. Fault signals
Several research papers on fault detection and reconfiguration for a CID have been elucidated in the last decade of the twentieth century. To begin with, Kastha and Bose [14] have investigated the possible fault modes of a voltage-fed inverter for induction motor drive. The method is based on mathematical model of possible faults and their consequences. The major fault modes based on mathematical models has been analyzed; specifically, input supply single line to ground faults, rectifier diode short circuit, inverter transistor base drive open circuit and inverter switch short circuit conditions. Although the research did not contribute a fault detection method, it provided an extensive study to design the zone of operation safely in a degraded mode of CID, which is important in high reliability applications. In addition, the research conveyed the available signals which can be used to detect particular faults as follows: • input rectifier current for detecting input supply single line to ground faults; • dc-link current and voltage for monitoring rectifier diode short circuit fault and over/under voltage; • input motor current for sensing inverter transistor base drive open circuit and inverter switch short circuit fault. Kastha [15, 16] also provided a single phase operation technique for a CID when a fault occurs in a leg of a CID; particularly, base drive open circuit and device short circuit. Assuming that the fault could correctly be detected and isolated, a CID could operate with a single-phase mode. The technique is based on torque compensation at an induction motor by injecting odd harmonic voltages at appropriate phase angles. In the next section, fault detection in an inverter of a CID system is described. 23
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 and 22: Advantages: • The number of possi
Page 23 and 24: VCA C C5 C4 C3 C2 120 o C1 A A5 A4
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: vehicle. It would be better if one
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
Page 77 and 78: The simulation model is illustrated
Page 79 and 80: Normal Fault A+ Fault A- Fault B+ F
Page 81 and 82: (a) (c) Figure 3.8. Experiment of o
Page 83 and 84: 3.4 Feature extraction system Simul
Page 85 and 86: Normal Fault A+ Fault A- Fault B+ F
Page 87 and 88:
X1 X2 X3 X4 X5 Xn Data PCA Scores t
Page 89 and 90:
Selecting a reduced subset (PCs kep
Page 91 and 92:
The collected data from both simula
Page 93 and 94:
Score PC1 Score PC1 -2 -4 -6 4 6 4
Page 95 and 96:
population created from multiple in
Page 97 and 98:
• Encoded input PCs: the PCs to b
Page 99 and 100:
andomly selects a crossover point w
Page 101 and 102:
Loadings on PC#13 Scores on PC#13 L
Page 103 and 104:
3.6 Neural network classification A
Page 105 and 106:
As a comparison among transformatio
Page 107 and 108:
Reselect training set Table 3.2. Ta
Page 109 and 110:
[42], is used to simulate the targe
Page 111 and 112:
The second category of testing resu
Page 113 and 114:
4. RECONFIGURATION TECHNIQUE 4.1 In
Page 115 and 116:
4.3 Reconfiguration method The reco
Page 117 and 118:
Amplitude (pu.) 1 0.8 0.6 0.4 0.2 0
Page 119 and 120:
traction motor only at half load co
Page 121 and 122:
% Relative to fundamental component
Page 123 and 124:
Van Vbn Vcn Vab Vbc Vca 100 0 -100
Page 125 and 126:
4.5 Summary The reconfiguration tec
Page 127 and 128:
5.2 Fault Diagnostic technique for
Page 129 and 130:
will be trained with short circuit
Page 131 and 132:
5.2.3 Principal component selection
Page 133 and 134:
5.3 Simulation validation Several S
Page 135 and 136:
The principal component analysis (P
Page 137 and 138:
1 p{1} a{1} Input 1 p{1} Subsystem
Page 139 and 140:
INV_A INV_B INV_C Showing the sub-s
Page 141 and 142:
Fault creating circuit RT-LAB comma
Page 143 and 144:
Figure 5.13. Obviously, the loss of
Page 145 and 146:
For the short circuit validation, t
Page 147 and 148:
Starting current Fault start (a) Fa
Page 149 and 150:
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
Page 155 and 156:
Fault start Fault clear Fault start
Page 157 and 158:
Table 5.3. Performance investigatio
Page 159 and 160:
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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