Development of Canned Line-start Rim-driven Electric Machines A thesis submitted to The University of Manchester for the degree of Doctor of Philosophy in the Faculty of Engineering and Physical Sciences 2011 Paul M. Tuohy School of Electrical and Electronic Engineering Contents Page Contents Page LIST OF FIGURES ........................................................................................................8 LIST OF TABLES ........................................................................................................15 LIST OF NOTATIONS................................................................................................18 LIST OF ACRONYMS ................................................................................................23 ABSTRACT...................................................................................................................25 DECLARATION...........................................................................................................27 COPYRIGHT STATEMENT......................................................................................28 ACKNOWLEDGEMENTS..........................................................................................29 CHAPTER 1 INTRODUCTION ...............................................................................31 1.1 LOW-SPEED DIRECT-DRIVE MACHINES..............................................................32 1.2 RIM-DRIVEN ELECTRIC MACHINES ....................................................................33 1.3 RESEARCH PROJECT APPROACH AND OBJECTIVES.............................................34 1.4 SIGNIFICANCE OF THE WORK .............................................................................35 1.5 THESIS STRUCTURE............................................................................................37 CHAPTER 2 LITERATURE REVIEW ...................................................................39 2.1 INTRODUCTION ..................................................................................................39 2.2 MARINE APPLICATIONS .....................................................................................39 2.2.1 Mechanical Propulsion System ...............................................................39 2.2.2 Electric Propulsion System......................................................................42 2.2.3 Hybrid-electric Propulsion System..........................................................46 2 Contents Page 2.2.4 Electric Motor Topologies.......................................................................46 2.2.5 AC Motor Topologies..............................................................................47 2.2.6 Induction Motors.....................................................................................47 2.2.7 Permanent-magnet Motors ......................................................................49 2.2.8 Superconducting Motors.........................................................................56 2.2.9 Electric Motor Torque-density Comparison............................................60 2.2.10 Failures of Electric Motors for Marine Propulsion .................................61 2.2.11 Electric Motor Propulsion Topologies ....................................................61 2.2.12 Controllable- and Fixed-pitch Propellers ................................................65 2.2.13 Summary..................................................................................................67 2.3 SEAL-LESS PUMP APPLICATION .........................................................................67 2.3.1 Background..............................................................................................67 2.3.2 Magnetic Coupling Pump........................................................................68 2.3.3 Canned Motor Pump................................................................................70 2.3.4 Rim-drive Motor Pump Design...............................................................71 2.3.5 Summary..................................................................................................72 2.4 RUN-OF-THE-RIVER RIM-DRIVEN GENERATOR APPLICATION ............................73 2.4.1 Background..............................................................................................73 2.4.2 Rim-driven Generator Concept...............................................................73 2.4.3 Summary..................................................................................................75 2.5 CONCLUSIONS....................................................................................................75 CHAPTER 3 BACKGROUND..................................................................................77 3.1 INTRODUCTION ..................................................................................................77 3.2 MAGNETIC MATERIALS THEORY .......................................................................77 3.3 PERMANENT-MAGNET MATERIALS ....................................................................81 3.3.1 Alnico Permanent-magnets .....................................................................81 3.3.2 Ceramic (ferrite) Permanent-magnets .....................................................82 3.3.3 Rare-earth Permanent-magnets ...............................................................82 3.4 UTILISATION OF PMS IN ELECTRIC MACHINES ..................................................84 3.5 FINITE ELEMENT ANALYSIS...............................................................................87 3.5.1 Introduction .............................................................................................87 3.5.2 History .....................................................................................................87 3.5.3 2-D versus 3-D FE Modelling .................................................................88 3 Contents Page 3.5.4 Flux2D FEA Software Package...............................................................89 3.6 CONCLUSIONS....................................................................................................93 CHAPTER 4 RIM-DRIVE TOPOLOGY CONCEPT STUDIES..........................94 4.1 INTRODUCTION ..................................................................................................94 4.2 RIM-DRIVE MARINE PROPULSION MOTOR .........................................................95 4.2.1 Introduction .............................................................................................95 4.2.2 Line-start Permanent-magnet Motor .......................................................96 4.2.3 Synchronisation Process..........................................................................97 4.2.4 LSPM Motor Topologies.........................................................................98 4.2.5 Canned LSPM Rim-drive Motor Concept.............................................101 4.2.6 Canned LSPM Rim-drive Motor Design...............................................103 4.2.7 Canned LSPM Rim-drive Motor FEA Predicted Performance.............110 4.2.8 Summary................................................................................................117 4.3 SEAL-LESS RIM-DRIVE MOTOR PUMP ..............................................................117 4.3.1 Introduction ...........................................................................................117 4.3.2 Application ............................................................................................118 4.3.3 Seal-less Rim-drive Motor Pump Design..............................................118 4.3.4 Seal-less Rim-drive Motor Pump FEA Predicted Performance............122 4.3.5 Summary................................................................................................130 4.4 DDAT RIM-DRIVE PROPULSION MOTOR .........................................................131 4.4.1 Introduction ...........................................................................................131 4.4.2 Application ............................................................................................131 4.4.3 DDAT Rim-drive Propulsion Motor Design.........................................133 4.4.4 DDAT Rim-drive Propulsion Motor FEA Predicted Performance .......137 4.4.5 Summary................................................................................................141 4.5 CONCLUSIONS..................................................................................................142 CHAPTER 5 PROTOTYPE RIM-DRIVE MOTOR FOR TIDAL STREAM TURBINE POSITIONING THRUSTER .................................................................144 5.1 INTRODUCTION ................................................................................................144 5.1.1 Background............................................................................................145 5.1.2 Requirement for a Bi-directional Thruster ............................................146 4 Contents Page 5.1.3 Operational Requirements for the Bi-directional Thruster....................146 5.1.4 Electric Bi-directional Thruster Design Considerations........................147 5.2 MARINE BIO-FOULING .....................................................................................148 5.3 ANALYTICAL CALCULATION OF THE KEY DESIGN PARAMETERS.....................149 5.3.1 Motor Design Loadings.........................................................................149 5.3.2 Calculation