Title Page
Contents
Abbreviations 16
Abstract 17
Chapter 1. INTRODUCTION 19
1.1. Background and Motivation 19
1.2. Literature Review of Energy Management for Fuel Cell Hybrid Power System 21
1.3. Research Objectives 25
1.4. Limitations 25
1.5. Outline 26
Chapter 2. HYBRID POWER SYSTEM MODEL 28
2.1. Hybrid Power System Description 28
2.2. Power Sources and Converters Models 30
2.2.1. Fuel Cell System Model 30
2.2.2. Battery Model 33
2.2.3. Supercapacitor Model 35
2.2.4. DC/DC Converters 37
2.2.5. Load Profile Model 38
2.3. Energy Management Strategy 39
2.4. Conclusion 43
Chapter 3. COMPREHENSIVE EMS BASED ON DETERMINISTIC-FREQUENCY DECOUPLING METHOD AND COMPENSATOR DESIGN 44
3.1. Introduction 44
3.2. Proposed Deterministic-Frequency Decoupling Method and Compensator Design 45
3.3. High-level Control Design 46
3.3.1. Frequency Decoupling Method 46
3.3.2. Deterministic Rule-Based Method 47
3.4. Low-Level Control Design 49
3.4.1. Design of SC Current Controller (PI-4 Controller) 50
3.4.2. Design of BAT Current Controller (PI-3 Controller) 52
3.4.3. Design of DC Bus Voltage Controller (PI-2 Controller) 53
3.4.4. Design of PEMFC Current Controller (PI-1 Controller) 55
3.4.5. SOC Regulators 56
3.5. Simulation Results 58
3.5.1. Case Study 1: Step-Changing Load 60
3.5.2. Case Study 2: Specific Driving Cycle 66
3.6. Experimental Results 72
3.7. Conclusion 76
Chapter 4. FUZZY LOGIC-BASED EMS 77
4.1. Introduction 77
4.2. Proposed Fuzzy Logic Rules-Based EMS 78
4.3. High-Level Control Design 79
4.4. Low-Level Control Design 82
4.5. Simulation Results 83
4.5.1. Case Study 1: Step-Changing Load 83
4.5.2. Case Study 2: Specific Driving Cycle 88
4.6. Experimental Results 93
4.7. Conclusion 95
Chapter 5. EXTREMUM SEEKING-BASED OPTIMIZATION FOR ENERGY MANAGEMENT STRATEGY 97
5.1. Introduction 97
5.2. Proposed Extremum Seeking-Based Optimization 99
5.3. High-Level Control 100
5.3.1. PEMFC Reference Power 100
5.3.2. Battery and Supercapacitor Reference Power 102
5.4. Low-Level Control 103
5.5. Simulation Results 105
5.5.1. Step-Changing Load 105
5.5.2. Specific Driving Cycle Load 111
5.6. Conclusion 116
Chapter 6. CONCLUSIONS AND FUTURE WORKS 118
6.1. Conclusions 118
6.2. Future Works 119
Publications 121
Bibliography 123
Table 2.1. Advantages and disadvantages of different EMSs 40
Table 3.1. Parameters of the SC bidirectional converter. 52
Table 3.2. Parameters of the BAT bidirectional converter. 53
Table 3.3. Parameters of the PEMFC converter. 56
Table 3.4. Specifications of PEMFC Horizon (H-200) 58
Table 3.5. SC bank parameters of DLCAP 59
Table 3.6. BAT parameters of Panasonic NCR18650BF 59
Table 3.7. EMS and controller parameters 60
Table 3.8. DC load simulator characteristics 73
Table 4.1. Fuzzy rules for the inputs and output membership functions. 81
Table 5.1. Comparison of existing control strategies for the HPS. 98
Table 5.2. Fuzzy rules for output battery power reference gain 103
Figure 1.1. Global energy-related greenhouse CO₂ emission. 19
Figure 1.2. Renewable electricity generation by source, World 1990 - 2018. 20
Figure 2.1. The response of PEMFC and energy sources. 28
Figure 2.2. Configuration of the hybrid power system. 29
Figure 2.3. The detailed model of the PEMFC stack. 30
Figure 2.4. The PEMFC polarization curves of voltage-current (U-I) and power-current (P-I). 33
Figure 2.5. Efficiency map of the 200-W PEMFC. 33
Figure 2.6. BAT equivalent model. 34
Figure 2.7. Polarization curves of the BAT. (a) Nominal current discharge characteristics. (b) Discharge current. 35
Figure 2.8. SC equivalent model. 36
Figure 2.9. The DC/DC converter models. (a) Unidirectional converter with boost mode. (b) Bidirectional converter with buck and boost modes. 38
Figure 2.10. Load profile models. (a) Step load power profile. (b) Specific driving cycle. 39
Figure 2.11. Classification of energy management systems. 41
Figure 3.1. The proposed energy management strategy for the hybrid power source. 46
Figure 3.2. Rangone diagram of power sources. 47
Figure 3.3. The flowchart of deterministic rule-based for fuel cell power distribution. 48
Figure 3.4. Current controller diagram of the SC converter. 50
Figure 3.5. Bode diagram of the SC current control loop. 51
Figure 3.6. Block diagram of the controllers for BAT converter. 52
Figure 3.7. Bode diagram of the BAT current control loop. 53
Figure 3.8. Bode diagram of the DC bus voltage control loop. 54
Figure 3.9. Current controller diagram of the PEMFC converter. 55
Figure 3.10. Bode diagram of the PEMFC current control loop. 56
Figure 3.11. The comparison of load power adaptation based on three EMSs. (a) The load power adaptation. (b) The power tracking error. 61
Figure 3.12. The power distribution of energy sources. (a) PEMFC. (b) BAT. (c) SC. 62
Figure 3.13. The DC bus voltage regulation. (a) Voltage tracking. (b) Tracking error. 63
Figure 3.14. The SOC status. (a) BAT SOC. (b) SC SOC. 64
Figure 3.15. The comparison of PEMFC stack efficiency. (a) Efficiency status. (b) Average efficiency. 65
Figure 3.16. The comparison of hydrogen (H2) consumption. (a) H2 consumption status. (b) Total H2 consumption. 66
Figure 3.17. The comparison of load power adaptation based on three EMSs. (a) The load power adaptation. (b) The power tracking error. 67
Figure 3.18. The power distribution of energy sources. (a) PEMFC. (b) BAT. (c) SC. 68
Figure 3.19. The DC bus voltage regulation. (a) Voltage tracking. (b) Tracking error. 69
Figure 3.20. The SOC status. (a) BAT SOC. (b) SC SOC. 70
Figure 3.21. The comparison of PEMFC stack efficiency. (a) Efficiency status. (b) Average stack efficiency. 71
Figure 3.22. The comparison of H2 consumption. (a) H2 consumption status. (b) Total H2 consumption. 71
Figure 3.21. The hybrid power system test bench. 72
Figure 3.22. The load power adaptation of three EMSs. (a) The tracking performance. (b) The power tracking error. 74
Figure 3.23. The power distribution of PEMFC, BAT, and SC by using the proposed EMS. 74
Figure 3.24. The comparison results of DC bus voltage by using three EMSs. (a) Voltage tracking. (b) Tracking error. 75
Figure 4.1. Proposed energy control strategy. 79
Figure 4.2. Inputs and output membership functions of the FLRs. (a) Input variable Pload. (b) Input variable SOCBAT. (c) Output variable PFC.[이미지참조] 80
Figure 4.3. The comparison of power adaptation of two EMSs. (a) The adaptation of load power. (b) The tracking error power. 84
Figure 4.4. The power distribution from energy sources. (a) PEMFC. (b)BAT. (c) SC. 85
Figure 4.5. The comparison of the DC bus voltage. (a) Voltage tracking. (b) Voltage tracking error. 86
Figure 4.6. The SOC comparison. (a) BAT SOC. (b) SC SOC. 86
Figure 4.7. The PEMFC stack efficiency. (a) Efficiency status. (b) Average efficiency. 87
Figure 4.8. The comparison of fuel consumption. (a) H2 consumption status. (b) Total H2 consumption. 88
Figure 4.9. The comparison of load power adaptation based on three EMSs. (a) The load power adaptation. (b) The power tracking error. 89
Figure 4.10. The power distribution of energy sources. (a) PEMFC. (b) BAT. (c) SC. 90
Figure 4.11. The DC bus voltage regulation. (a) Voltage tracking. (b) Tracking error. 91
Figure 4.12. The SOC status. (a) BAT SOC. (b) SC SOC. 91
Figure 4.13. The comparison of PEMFC stack efficiency of PEMFC stack. (a) Efficiency status. (b) Average stack efficiency. 92
Figure 4.14. The comparison of hydrogen consumption. (a) H2 consumption status. (b) Total H2 consumption. 93
Figure 4.15. The load power adaptation of three EMSs. (a) The tracking performance. (b) The power tracking error. 94
Figure 4.16. The power distribution of PEMFC, BAT, and SC by using the proposed EMS. 94
Figure 4.17. The comparison results of DC bus voltage by using three EMSs. 95
Figure 5.1. Multi-level control scheme of the proposed ES-based EMS. 99
Figure 5.2. MFs of inputs and output of the fuzzy operator for the BAT and SC power split. 103
Figure 5.3. Structure of low-level control. 104
Figure 5.4. The comparison of load power adaptation based on three EMSs. (a) The load power adaptation. (b) The power tracking error. 106
Figure 5.5. The power distribution of energy sources. (a) PEMFC. (b) BAT. (c) SC. 107
Figure 5.6. The DC bus voltage regulation. (a) Voltage tracking. (b) Tracking error. 108
Figure 5.7. The SOC status. (a) BAT SOC. (b) SC SOC. 109
Figure 5.8. The PEMFC stack efficiency. (a) Efficiency status. (b) Average efficiency. 109
Figure 5.9. The comparison of fuel consumption. (a) H2 consumption status. (b) Total H2 consumption. 110
Figure 5.10. Load satisfaction under three strategies. (a) Load tracking performance. (b) Tracking error performance. 111
Figure 5.11. The power distribution of energy sources. (a) PEMFC. (b) BAT. (c) SC. 112
Figure 5.12. The DC bus voltage regulation. (a) Voltage tracking. (b) Tracking error. 113
Figure 5.13. The SOC status. (a) BAT SOC. (b) SC SOC. 114
Figure 5.14. The comparison of PEMFC stack efficiency of PEMFC stack. (a) Efficiency status. (b) Average stack efficiency. 115
Figure 5.15. The comparison of hydrogen consumption. (a) H2 consumption status. (b) Total H2 consumption. 115