Title Page
Contents
Abbreviations 17
ABSTRACT 18
Chapter 1. INTRODUCTION 20
1.1. Overview 20
1.1.1. Structure of hybrid hydraulic excavator 21
1.1.2. Potential energies 22
1.1.3. Drawback of previous research 23
1.2. Research objectives 26
1.3. Limitations 27
1.4. Thesis outline 27
Chapter 2. DEVELOPMENTS OF HYBRID HYDRAULIC EXCAVATOR (HHE) 29
2.1. Introduction 29
2.2. Powertrain configurations of hybrid HE 29
2.2.1. Series powertrain configuration 30
2.2.2. Parallel powertrain configuration 32
2.2.3. Series-parallel powertrain configuration 33
2.3. Types of Boom, Arm, and Bucket energy regeneration technologies 34
2.3.1. ERS using electrical energy storages 35
2.3.2. ERS using hydraulic storage 43
2.3.3. ERS using mechanical storage 52
2.3.4. Types of Swing energy regeneration technologies 53
2.4. Challenges 58
Chapter 3. ELECTRICAL HYDRAULIC CONTINUALLY VARIABLE POWERTRAIN 60
3.1. Introduction 60
3.2. System structure 62
3.3. Experiment test bench 65
3.4. EHCVP model 68
3.4.1. Boom up process 68
3.4.2. Boom down process 69
3.4.3. Lithium-Ion battery model 73
3.5. Experiment and analysis 73
3.5.1. Working performance of EHCVP 73
3.5.2. Energy saving efficiency in different conditions 78
3.5.3. Economic analysis of proposed system 79
3.6. Chapter summary 81
Chapter 4. IMPROVEMENT OF ENERGY SAVING 82
4.1. Introduction 82
4.2. Working principle 83
4.3. Modification of experiment test bench 85
4.4. Energy management strategy 86
4.5. Simulation results and discussions 88
4.5.1. Working performance of modified EHCVP 88
4.5.2. Extremum seeking control with constraint conditions 93
4.6. Experimental results discussions 95
4.7. Chapter summary 97
Chapter 5. ADVANCED ENERGY MANAGEMENT STRATEGY 99
5.1. Introduction 99
5.1.1. Overview 99
5.1.2. Proposed energy management strategy based on fuzzy ESC 99
5.2. Lithium-Ion battery degradation model 100
5.3. Constraint problems in the ESC 100
5.3.1. Fix-Constraint ESC 100
5.3.2. Proposed Fuzzy-Constraint ESC 101
5.4. Simulation results and discussions 103
5.4.1. Simulation description 103
5.4.2. Experiment description 113
5.5. Chapter Summary 123
Chapter 6. CONCLUSION AND FUTURE WORKS 124
6.1. Conclusions 124
6.2. Future works 124
Publish papers and patents 126
References 129
Table 1-1. Potential energies in HE. 23
Table 2-1. comparison of 3 above configurations 34
Table 2-2. Technology summary table of ERS using electrical storage. 42
Table 2-3. Technology summary table of ERS using hydraulic storage. 50
Table 2-4. Technology summary table of swing ERS. 57
Table 3-1. comparison of 3 above configurations 67
Table 3-2. Energy consumption 78
Table 3-3. Results of energy saving efficiency 79
Table 4-1. Total energy consumption and energy saving 93
Table 4-2. Comparison of energy consumption 97
Table 5-1. Fuzzy rule of current status 101
Table 5-2. Fuzzy rule of current status and temperature with Jconstraint[이미지참조] 103
Table 5-3. Fuzzy rule of current status and SOC with Jconstraint[이미지참조] 103
Table 5-4. Fuzzy rule of SOC and temperature with Jconstraint[이미지참조] 103
Table 5-5. Initial values of SOC and temperature in different cases 103
Table 5-6. Comparation table of simulation results of a 50000 cycles projection 113
Table 5-7. Summary table of constraint 122
Table 5-8. Comparation table of experimental results of a 50000 cycles projection 122
Fig. 1-1. Total final consumption by source, World 1990-2017. 20
Fig. 1-2. CO2 emissions by energy source, World 1990-2017 21
Fig. 1-3. Layout of a typical hydraulic excavator 21
Fig. 1-4. Power requirement of HE in digging condition. 23
Fig. 1-5. Recoverable energy of the boom cylinder in digging condition. 23
Fig. 2-1. The conventional powertrain configuration on a construction machine 29
Fig. 2-2. The amount of heat generated by fuel 30
Fig. 2-3. The energy flow in typical work of a hydraulic excavator 30
Fig. 2-4. The typical series powertrain configuration on engine hybrid construction machinery 31
Fig. 2-5. Series powertrain configuration of ZW220HYB-5B wheel loader introduced by Hitachi 31
Fig. 2-6. The series powertrain configuration on KOBELCO 6-ton class machines 32
Fig. 2-7. The typical parallel powertrain configuration in construction machines 32
Fig. 2-8. System outline of the HITACHI hybrid wheel loader 33
Fig. 2-9. The typical compound powertrain configuration 33
Fig. 2-10. Block diagram of Kobelco 8-ton class series-parallel excavator SK80H 34
Fig. 2-11. Different structures of HE. (a) Series type. (b) Parallel type. (c) Compound type. 36
Fig. 2-12. Distribution of engine working points with the hybrid system. 36
Fig. 2-13. A classical ERS using electrical storage. 37
Fig. 2-14. Structure of the energy recovery controller. 37
Fig. 2-15. The electric HE using EHA. 38
Fig. 2-16. Structure of electric HE using the variable pump and the servo motor. 39
Fig. 2-17. Energy efficiency controller. 39
Fig. 2-18. Power source control strategy and efficiency map of the pump. 39
Fig. 2-19. ERS of boom system using an additional flow control valve. 40
Fig. 2-20. ERS of boom system with additional hydraulic accumulator. 41
Fig. 2-21. Distribution of the working points of the generator with the hydraulic accumulator(AMGERS) and without hydraulic accumulator (JMGERS). 41
Fig. 2-22. Schematic of the ERS using hydraulic storage. 44
Fig. 2-23. Schematic of the potential energy recovery system of the HHE using the electro-hydraulic actuator (EHA). 45
Fig. 2-24. Structure of the Common Pressure Rail system. 46
Fig. 2-25. Working points occurrence frequency map under adjustable single point strategy. 46
Fig. 2-26. Working principle of the balance boom cylinder system. 47
Fig. 2-27. Operating points over five excavation cycles. 47
Fig. 2-28. Schematic diagram of the closed-circuit gravitational potential energy regeneration system (GPERS) of the boom. 48
Fig. 2-29. Test schematic of the double and three-chamber cylinder systems. 48
Fig. 2-30. Pressures and displacement of three chambers cylinder. 49
Fig. 2-31. Principle and structure of the novel-designed asymmetric pump system. 50
Fig. 2-32. Working principle and the image of the valve plate and cylinder block. 50
Fig. 2-33. Structure of a flywheel mechanical ERS. 53
Fig. 2-34. Schematic of hydraulic ERS swing system. 54
Fig. 2-35. The ERSs of the swing system using two pair of hydraulic pump and motor. 54
Fig. 2-36. Hydraulic circuit of the ERS system using an accumulator and a flow control valve. 55
Fig. 2-37. Hydraulic circuit of the ERS system using two independence accumulators. 56
Fig. 2-38. Proposed ERS system using accumulator for swing acceleration process. 57
Fig. 3-1. Structure of the proposed boom system with EHCVP. 62
Fig. 3-2. Working principle of EHCVP in normal mode. 63
Fig. 3-3. Working principle of EHCVP in hybrid mode. 64
Fig. 3-4. Working principle of EHCVP in reuse mode. 64
Fig. 3-5. Working principle of EHCVP in regeneration mode. 65
Fig. 3-6. Boom cylinder and powertrain in experiment test bench. 66
Fig. 3-7. Hydraulic system and control box in experiment test bench. 66
Fig. 3-8. Comparison of engine control in the real excavator and the experiment. 67
Fig. 3-9. Engine efficiency map. 70
Fig. 3-10. Mechanical efficiency map of the pump at 20 bar. 71
Fig. 3-11. Volume efficiency map of pump at 20 bar. 71
Fig. 3-12. Electric motor/generator efficiency map. 71
Fig. 3-13. Hydraulic motor efficiency map. 72
Fig. 3-14. Displacement of cylinder under three driving cycles (NM: normal mode, RM: regeneration mode, HM: hybrid mode, RUM, reuse mode). 73
Fig. 3-15. Velocity of cylinder under three driving cycles 74
Fig. 3-16. Pressure of cylinder under three driving cycles 74
Fig. 3-17. Flow rate of the cylinder under three driving cycles 74
Fig. 3-18. Speed of ICE and electric motor/generator 75
Fig. 3-19. Torque of ICE and electric motor/generator 76
Fig. 3-20. Energy consumption of EHCVP system 76
Fig. 3-21. Displacement of cylinder in conventional system 77
Fig. 3-22. Velocity of cylinder in conventional system 77
Fig. 3-23. Speed of ICE and electric motor/generator in conventional system 77
Fig. 3-24. Torque of ICE and electric motor/generator in conventional system 78
Fig. 3-25. Energy consumption of conventional system 78
Fig. 3-26. Typical working cycle of boom in hydraulic excavator 79
Fig. 3-27. Cylinder displacement of both EHCVP and conventional systems 79
Fig. 3-28. Fuel consumption of EHCVP system 80
Fig. 3-29. Fuel consumption of conventional system 80
Fig. 4-1. Structure of the EHCVP I 82
Fig. 4-2. Structure of the proposed boom system with EHCVP II 83
Fig. 4-3. Modification of the experiment test bench 85
Fig. 4-4. Proposed energy management strategy 86
Fig. 4-5. Proposed extremum seeking based energy management strategy for EHCVP system 87
Fig. 4-6. Simulation model in AMESim software 89
Fig. 4-7. Cylinder displacement during the operation 89
Fig. 4-8. Pressure and flow rate of the boom cylinder 89
Fig. 4-9. Switching gear ratio 89
Fig. 4-10. Power distribution in EHCVP II 90
Fig. 4-11. Speed of the ICE and electric motor/generator in EHCVP II 90
Fig. 4-12. Torque of the ICE and electric motor/generator in EHCVP II 90
Fig. 4-13. Power distribution in conventional EHCVP I 91
Fig. 4-14. Speed of the ICE and electric motor/generator in conventional EHCVP I 91
Fig. 4-15. Torque of the ICE and electric motor/generator in conventional EHCVP I 92
Fig. 4-16. Efficiency comparation 93
Fig. 4-17. SOC of battery. 93
Fig. 4-18. SOC of battery with constraints. 93
Fig. 4-19. Power distribution with constraints. 94
Fig. 4-20. Power distribution without constraints. 94
Fig. 4-21. Experimental results with EHCVP II. 95
Fig. 4-22. Experimental results with EHCVP I. 96
Fig. 4-23. Experimental results with conventional system. 96
Fig. 4-24. Working points of engine. 96
Fig. 5-1. Proposed fuzzy extremum seeking based energy management strategy. 99
Fig. 5-2. MFs for input and output of battery's current status. 101
Fig. 5-3. MFs for input and output of penalty function Jconstraint.[이미지참조] 102
Fig. 5-4. Power distribution by using proposed Fuzzy ESC in case 1. 104
Fig. 5-5. Power distribution by using Fixed Constraint ESC in case 1. 104
Fig. 5-6. Power distribution by using Non-Constraint ESC in case 1. 105
Fig. 5-7. Power distribution by using ECMS in case 1 105
Fig. 5-8. Engine efficiencies with different control strategies in case 1. 105
Fig. 5-9. Current of battery with different control strategies in case 1. 105
Fig. 5-10. Power distribution by using proposed Fuzzy ESC in case 2. 106
Fig. 5-11. Power distribution by using Fixed Constraint ESC in case 2. 106
Fig. 5-12. Power distribution by using Non-Constraint ESC in case 2. 107
Fig. 5-13. Power distribution by using ECMS in case 2. 107
Fig. 5-14. SOC of battery with different control strategies in case 2. 107
Fig. 5-15. Power distribution by using proposed Fuzzy ESC in case 3. 108
Fig. 5-16. Power distribution by using Fixed Constraint ESC in case 3. 108
Fig. 5-17. Power distribution by using Non-Constraint ESC in case 3. 109
Fig. 5-18. Power distribution by using ECMS in case 3. 109
Fig. 5-19. SOC of battery with different control strategies in case 3. 109
Fig. 5-20. Temperature of battery with different control strategies in case 3. 110
Fig. 5-21. Power distribution by using proposed Fuzzy ESC in case 4. 110
Fig. 5-22. Power distribution by using Fixed Constraint ESC in case 4. 111
Fig. 5-23. Power distribution by using Non-Constraint ESC in case 4. 111
Fig. 5-24. Power distribution by using ECMS in case 4. 111
Fig. 5-25. Current of battery with different control strategies in case 4. 111
Fig. 5-26. SOC of battery with different control strategies in case 4. 112
Fig. 5-27. Temperature of battery with different control strategies in case 4. 112
Fig. 5-28. Power allocation by using proposed Fuzzy ESC in case 1. 113
Fig. 5-29. Power allocation by using Fixed Constraint ESC in case 1. 114
Fig. 5-30. Power allocation by using Non-Constraint ESC in case 1. 114
Fig. 5-31. Power allocation by using ECMS in case 1. 114
Fig. 5-32. Efficiency of engine in case 1 based on experiment results 115
Fig. 5-33. SOC of battery in case 1 based on experiment results. 115
Fig. 5-34. Current of battery in case 1 based on experiment results. 115
Fig. 5-35. Power allocation by using proposed Fuzzy ESC in case 2. 116
Fig. 5-36. Power allocation by using Fixed Constraint ESC in case 2. 116
Fig. 5-37. Power allocation by using Non-Constraint ESC in case 2. 116
Fig. 5-38. Power allocation by using ECMS in case 2. 117
Fig. 5-39. SOC of battery in case 2 based on experiment results. 117
Fig. 5-40. Power allocation by using proposed Fuzzy ESC in case 3. 117
Fig. 5-41. Power allocation by using Fixed Constraint ESC in case 3. 118
Fig. 5-42. Power allocation by using Non-Constraint ESC in case 3. 118
Fig. 5-43. Power allocation by using ECMS in case 3. 118
Fig. 5-44. Temperature of battery in case 3 based on experiment results. 119
Fig. 5-45. SOC of battery in case 3 based on experiment results. 119
Fig. 5-46. Power allocation by using proposed Fuzzy ESC in case 4. 119
Fig. 5-47. Power allocation by using Fixed Constraint ESC in case 4. 120
Fig. 5-48. Power allocation by using Non-Constraint ESC in case 4. 120
Fig. 5-49. Power allocation by using ECMS in case 4. 120
Fig. 5-50. Current of battery in case 4 based on experiment results. 121
Fig. 5-51. SOC of battery in case 4 based on experiment results. 121
Fig. 5-52. Temperature of battery in case 4 based on experiment results. 121