Title Page
Contents
1. Introduction 10
1.1. Switched Reluctance Motors: Advantages and Drawbacks 10
1.2. Research Motivation 12
1.3. Research Objective 13
1.4. Thesis Organization 14
2. SRM Fundamentals and Sensorless Controls 16
2.1. Introduction 16
2.2. Basic SRM Principles 16
2.2.1. SRM Drive and Equations 17
2.2.2. SRM Energy Conversion 19
2.2.3. SRM Torque Production 25
2.3. Review of Sensorless Methods for SRMs 29
2.3.1. Current Gradient Sensorless Method 32
3. Proposed Sensorless Control Method 35
3.1. Phase Initialization 35
3.2. Current Threshold Scheme 38
3.3. Transition Between the Two Phases 42
3.4. Speed Estimation 43
4. Results of the Proposed Sensorless Control Method 45
4.1. Simulation of the SRM 45
4.2. Simulation Results 50
4.2.1. Low Speed Sensorless Control 50
4.2.2. High Speed Sensorless Control 51
4.3. Experimental Results 57
4.3.1. Experimental Setup 57
4.3.2. Phase Initialization 57
4.3.3. Current Threshold Scheme 61
5. Conclusion 67
References 68
Abstract 72
Publications 75
Table 4-1. [제목없음] 48
Figure 2.1. A conventional SRM and asymmetric half-bridge converter 17
Figure 2.2. Basic SRM equivalent circuit 18
Figure 2.3. Flux flow of a 4/2 SRM 20
Figure 2.4. Flux-current relationship for: (a) linear and (b) non-linear systems 21
Figure 2.5. Stored field energy on the λ - i curve 23
Figure 2.6. Increase in stored energy because of change in airgap 24
Figure 2.7. Ideal SRM excitation and torque production 27
Figure 2.8. Conventional SRM excitation 28
Figure 2.9. Sensorless control methods 30
Figure 2.10. Sensorless control methods according to speed 31
Figure 2.11. Phase currents at low- and high- speed ranges 32
Figure 2.12. key positions of phase current during single-pulse excitation 33
Figure 2.13. Variations of the current gradient method. 34
Figure 3.1. Flow chart of phase initialization 37
Figure 3.2. Phase currents and respective inductance plots 38
Figure 3.3. Key positions of one phase current 39
Figure 3.4. Proposed current threshold method for turn-off 40
Figure 3.5. Proposed current threshold method for turn-on 40
Figure 3.6. Flow chart of current threshold scheme 41
Figure 3.7. Speed range of the motor 43
Figure 3.8. Speed Estimation using CGS 44
Figure 4.1. MATLAB model of a 4/2 SRM 46
Figure 4.2. Electrical block diagram of the model 46
Figure 4.3. Mechanical block diagram of the model. 47
Figure 4.4. Static inductance characteristic 48
Figure 4.5. Static flux linkage characteristic 49
Figure 4.6. Static torque characteristic 49
Figure 4.7. Starting procedure 50
Figure 4.8. Open-loop speed up 51
Figure 4.9. Variation of the peak current position 52
Figure 4.10. Effect of changing current values on thresholds 53
Figure 4.11. Simulation results when using CTS with 45% off threshold 54
Figure 4.12. Simulation results when using CTS with 60% off threshold 55
Figure 4.13. Simulation results when using CTS with 30% off threshold 56
Figure 4.14. Experimental setup 57
Figure 4.15. Initial pulse injection with phase A 58
Figure 4.16. Starting mechanism with phase B 58
Figure 4.17. Operation of the motor using the proposed method using CTS 59
Figure 4.18. Phase initialization using proposed method (A) 60
Figure 4.19. Open loop acceleration of motor (B) 61
Figure 4.20. Peak detection 62
Figure 4.21. Position estimation during transient conditions (C) 63
Figure 4.22. Position estimation during steady state conditions (D) 64
Figure 4.23. Speed estimation of the proposed control method 65
Figure 4.24. Close up of mode change 66