Electrical Machines For Renewable Energy Converters Dr. Markus Mueller School of Engineering University of Edinburgh
Presentation <ul><li>Renewable Energy Systems </li></ul><ul><li>Electrical Drivetrain Technology </li></ul><ul><li>Challen...
Wind Energy
 
Wind Drivetrain
Direct Drive Wind <ul><li>Enercon E112 </li></ul><ul><li>4.5MW </li></ul><ul><li>220 tons </li></ul><ul><li>Iron cored fie...
Wave Energy
Global Wave Energy Resource
EU Wave Energy Resource Source : Future Energy Solutions <ul><ul><li>UK Resource </li></ul></ul><ul><ul><li>Offshore: 50TW...
Oscillating Water Column <ul><li>Wave energy conversion device </li></ul><ul><li>LIMPET on Islay since 2000 </li></ul><ul>...
Oscillating Water Column (OWC) Shoreline and near shore ©  Wavegen
Pelamis Full Scale – 750kW Image © Aquatera.co.uk
Pelamis Wave Power ©  Pelamis Wave Power <ul><li>Pelamis – sea snake </li></ul><ul><li>Designed for survivability </li></u...
Pelamis – power take off <ul><li>Cylindrical sections connected by hinged joints </li></ul><ul><li>Motion of joints resist...
Hydraulic Power Take Off
Aquamarine <ul><li>Hydro Technology  </li></ul><ul><li>Pelton Turbine driving Synchronous Machine </li></ul>© Aquamarine
Oyster – Testing at EMEC © Aquamarine
Point Absorber: Archimedes Wave Swing ©  AWS BV Move with incident waves either in surge or heave mode and is very small c...
AWS Electrical Power Conversion <ul><li>Linear PM synchronous machine </li></ul><ul><li>Rating – 2MW </li></ul><ul><li>Ave...
Marine Current Turbines <ul><li>Axial flow turbine </li></ul><ul><li>SEAFLOW: 300 kW unit; Lynmouth, North Devon Coast </l...
Tidal Current Direct Drive: Open Hydro <ul><li>Rim Generator </li></ul><ul><li>Air-cored PM generator </li></ul><ul><li>Fu...
ScotRenewables <ul><li>Floating Turbine </li></ul><ul><li>Hydraulic Power Take Off </li></ul><ul><li>Induction Generator <...
Engineering Challenges <ul><li>Low speed </li></ul><ul><ul><li>Wind: 1MW – 20rpm, 7MW – 10rpm </li></ul></ul><ul><ul><li>W...
Engineering Challenge <ul><li>Variable prime mover  </li></ul><ul><li>Wave: </li></ul>
Challenge Example - Oyster 6 m Diameter £ 3,182k Total Cost  £ 116k Power Electronics Cost £  3,066k Total Generator Cost ...
Single Stage Gearbox <ul><li>Direct Drive </li></ul><ul><ul><ul><li>Maximum Reliability </li></ul></ul></ul><ul><ul><ul><l...
Designs with Different Gear Ratios
Integrated Design Wind speed distribution Wind turbine model Generator model Axial-flux Electrical model Structural model ...
Hydrodynamic model Generator model Electrical model Structural model Criterion calculation Thermal model Design Optimisati...
Structural Modelling of Direct Drive
What does this modelling tell us? <ul><li>Structural material is dominant </li></ul><ul><li>Optimal aspect ratios are larg...
Structural Optimisation
Integrated Electromagnetic-Structural Optimization <ul><ul><li>A FEA optimisation tool was created to further decrease the...
Induction Generator Modelling  for OWCs - Wavegen Airflow and generator power  recorded during OWC operation Recorded casi...
Solutions to Challenges <ul><li>Power Density or Mass </li></ul><ul><ul><li>Transverse Flux Machine  </li></ul></ul><ul><u...
Magnetic Gearing: SNAPPER Armature Translator Springs Copper Winding / Coil Stack Length,  l s
F drive F spring F drive F spring Phase 1 Spring force is less than magnetic attraction force: Translator and armature mov...
Dry Testing
Dry Testing Video <ul><li>Dry Testing video </li></ul>
Economic – PM availability <ul><li>Switched Reluctance </li></ul><ul><ul><li>No permanent magnet material </li></ul></ul><...
Experimental Prototype 20 kW at 100 rpm
Switched Reluctance with Segmental Rotor  <ul><li>Prof Barrie Mecrow, University of Newcastle </li></ul>TOPOLOGIES FOR WOU...
Switched Reluctance with Segmental Rotor  <ul><li>65% improvement in Torque Density (Nm/kg) compared conventional. </li></...
Transverse Flux Machines <ul><li>High Shear Stress at the airgap </li></ul><ul><ul><li>200kN/m 2  reported by Weh  </li></...
What type of TFPM machine ? A number of TFPM machine types have been proposed.    It is necessary to find the most suitab...
Comparative design of PM machines a) RFPM machine  b) TFPM machine-1  c) TFPM machine-2 d) TFPM machine-3  e) TFPM machine-4
Design parameters 12 Rotational speed,  rpm 3 Number of phase,  m 675 A Nominal current,  i s 2746 V No-load voltage,  e p...
Comparison
Comparative design of PM machines a) RFPM machine  b) TFPM machine-1  c) TFPM machine-2 d) TFPM machine-3  e) TFPM machine-4
PM Air-cored Machines <ul><li>Stator winding contains no iron. </li></ul><ul><li>Elimination of magnetic attraction forces...
PM machines Copper Steel PM Stator Rotor Rotor <ul><li>Iron-cored  machines: </li></ul><ul><ul><li>High flux density and s...
Air cored PM: SLIM & Goliath
Goliath – 250kW <ul><li>Spoked Structure </li></ul><ul><li>Airgap Winding, steel surrounding winding </li></ul>
Open Hydro
Air-cored Machines:C-GEN
C-GEN modular assembly Rotor Stator Mild steel C-core Magnets
C-GEN final assembly <ul><li>PM Generators </li></ul><ul><ul><li>Assembly is difficult and dangerous </li></ul></ul><ul><u...
C-GEN Mk I: 20 kW Prototype Results Power 21.5 kW Outer radius 502 mm Efficiency 93 % Machine length 500 mm Speed 100 rpm ...
C-GEN MkII: 15kW results rpm
Linear C-GEN for Wave <ul><li>50kW (pk) </li></ul><ul><li>Vpk = 2m/s </li></ul><ul><li>Machine Length = 3m </li></ul><ul><...
High Temperature Superconducting Machines <ul><li>36.5 MW, 120 rpm (U.S. Navy, AMSC) </li></ul>American Superconductor Coorp
HTS Context <ul><li>Larger Offshore Wind Turbines (>5MW) </li></ul><ul><li>Gearboxes unfeasible </li></ul><ul><li>Direct D...
Types of HTS Machines <ul><li>Rotating DC Superconducting Field </li></ul><ul><ul><li>Most Common Type </li></ul></ul><ul>...
HTS Machines – Claw Pole <ul><li>Stationary HTS coil to provide field excitation </li></ul><ul><li>Air-cored winding  </li...
Claw Pole HTS Generator
Future <ul><li>Low speed </li></ul><ul><ul><li>Direct Drive </li></ul></ul><ul><ul><li>Single Stage Gear Box </li></ul></u...
Acknowledegements <ul><li>Scottish Enterprise </li></ul><ul><li>The Carbon Trust </li></ul><ul><li>npower juice </li></ul>...
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Electrical machines for renewable energy converters keynote

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Dr. Markus Mueller
IET- Renewable Power Generation, Edinburgh, 2011
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  • MM
  • Perhaps add in some figures on global market from Future Energy Solutions – p8
  • Map of UK with resource, and a summary of bullet points of technical available resource
  • OWC – picture and describe the main components in the system – comment on efficiency of Wells Turbine
  • Picture of pelamis and bullet points of power conversion – SRO contract
  • NEED TO GET BETTER PICTURE
  • Picture and info on direct drive power take off
  • Better picture of SEAGEN
  • Example of Challenge facing Direct Drive in Wave Energy
  • Importance of structural material: From cost and mass point of view: Electromagnetic only: Small aspect ratio; reduce magnet and copper material Electromagnetic and structural material: Increase aspect ratio – smaller diameter and longer; large radius means lots of structural material Normally have airgap length as fixed % of airgap diameter (0.1%) From cost and mass point of view: Better to have larger airgap length and allow structure to be less stiff
  • The structural optimization highlighted the danger in not optimizing the active and inactive material together a generator design that minimizes active mass leads to a design that maximizes inactive/structural mass. The integrated electromagnetic–structural optimization indicated that machines with a larger airgap will result in lower mass! Traditionally, the airgap is kept as small as possible to optimize the electromagnetic performance. For minimum mass, large aspect ratios (ratio of length to airgap radius) with a larger airgap is desirable, leading to a sausage shaped machine. For minimum cost, small aspect ratios or pancake machines are more desirable, because active mass decreases with radius, and this forms the most expensive part of the generator.
  • OWC has air-flow over generator. Air-flow assists cooling of generator - include in thermal model 16% additional power achievable without exceeding temperature limits of machine
  • Go through main characteristics, pros &amp; cons
  • In the case of TFPM machine, a number of electromagnetic topologies have been proposed as shown in this slide. For large direct-drive wind generators, what type of TFPM machine can be the most suitable? Therefore, it is necessary to find the most suitable type. But, how?
  • RF machine with surface mounted PM has been discussed as a better choice for large direct-drive wind in references. Therefore, RF machine with surface mounted PM is selected as the RFPM machine for this comparative design. The flux-concentrating TFPM machine has higher force density than other topologies. The single-winding type is simple in construction. Therefore, four different flux-concentrating single-winding TFPM machines are selected for this comparative design. The selected machine types are named as this slide.
  • 5 MW five different PM machines have been designed and compared electromagnetically in terms of mass, cost and loss. In the figure of right side, the criteria values of each concept are divided by RFPM criteria which are the copper loss, the mass/power ratio m/P , the cost/power ratio cost/P , and the cost/mass ratio Cost/m , respectively. The copper losses of TFPM machines are significantly lower than the RFPM machine. The RFPM machine is the 3rd in mass , the 2nd in cost , and the 2nd in cost/m among the five generators. TFPM machine-2, which has the double-sided air gap and single-winding with C-cores, seems the best concept considering all criteria. However, to maintain the double-sided air gap is difficult in constructing. Regarding construction, TFPM machine-1 seems a better choice than TFPM machine-2 concept. However, TFPM-1 is heavier than RFPM. Therefore, when TFPM-1 is selected, it is required to reduce the mass and cost of TFPM-1 further to overcome RFPM.
  • RF machine with surface mounted PM has been discussed as a better choice for large direct-drive wind in references. Therefore, RF machine with surface mounted PM is selected as the RFPM machine for this comparative design. The flux-concentrating TFPM machine has higher force density than other topologies. The single-winding type is simple in construction. Therefore, four different flux-concentrating single-winding TFPM machines are selected for this comparative design. The selected machine types are named as this slide.
  • 16m diameter, 500kW in low tidal currents, to be installed off Northern France Airgap winding similar to Goliath Ed Spooner is the main designer of the machine
  • AM One of the unique features of the C-GEN is it’s modular assembly The C-GEN rotor (which is coupled to the wind turbine blades) was made from 32 C-cores; each made machined standard mild steel pieces; PMs attached and then combined to make the C-cores; and then these were then brought together with 2 aluminium discs and the rotor shaft. The stator (which carries the electrical winding) is made up of 24 coil modules; these are combined to give a complete stator
  • Other permanent magnet generator technologies are difficult and dangerous to assemble, because there are large forces of attraction between the rotor and stator modules. This typically requires hydraulic jacks and manpower. The C-GEN design does not have this problem, so the stator can be easily lowered into place, here by an engine hoist. Potential savings for large size, large scale production are significant. Benefit for maintenance too.
  • AM - The C-GEN Mk I 20kW has been built and successfully tested on the test rig at Edinburgh. We have produced high efficiencies over the whole load range and verified our initial designs.
  • Electrical machines for renewable energy converters keynote

    1. 1. Electrical Machines For Renewable Energy Converters Dr. Markus Mueller School of Engineering University of Edinburgh
    2. 2. Presentation <ul><li>Renewable Energy Systems </li></ul><ul><li>Electrical Drivetrain Technology </li></ul><ul><li>Challenges – engineering & economic </li></ul><ul><li>Integrated Design Tools </li></ul><ul><li>Electrical Machine Topologies </li></ul><ul><li>Future Developments </li></ul>
    3. 3. Wind Energy
    4. 5. Wind Drivetrain
    5. 6. Direct Drive Wind <ul><li>Enercon E112 </li></ul><ul><li>4.5MW </li></ul><ul><li>220 tons </li></ul><ul><li>Iron cored field wound synchronous machine </li></ul><ul><li>Large magnetic attraction forces between stator and rotor. </li></ul><ul><li>Structural support >60% of total mass. </li></ul>
    6. 7. Wave Energy
    7. 8. Global Wave Energy Resource
    8. 9. EU Wave Energy Resource Source : Future Energy Solutions <ul><ul><li>UK Resource </li></ul></ul><ul><ul><li>Offshore: 50TWh/year (1/7 th UK Electricity Production) </li></ul></ul><ul><ul><li>Near-shore: 7.8TWh/year </li></ul></ul><ul><ul><li>Shoreline: 0.2TWh/year </li></ul></ul>
    9. 10. Oscillating Water Column <ul><li>Wave energy conversion device </li></ul><ul><li>LIMPET on Islay since 2000 </li></ul><ul><li>Turbines delivered to Mutriku, Spain </li></ul><ul><li>4MW scheme on Lewis consented </li></ul>
    10. 11. Oscillating Water Column (OWC) Shoreline and near shore © Wavegen
    11. 12. Pelamis Full Scale – 750kW Image © Aquatera.co.uk
    12. 13. Pelamis Wave Power © Pelamis Wave Power <ul><li>Pelamis – sea snake </li></ul><ul><li>Designed for survivability </li></ul><ul><li>Uses off the shelf components </li></ul><ul><li>A 750 kW device will be 150m long and 3.5m in diameter. </li></ul><ul><li>Hydraulic PTO </li></ul><ul><li>Generators </li></ul><ul><ul><li>Squirrel Cage Induction Machine </li></ul></ul>
    13. 14. Pelamis – power take off <ul><li>Cylindrical sections connected by hinged joints </li></ul><ul><li>Motion of joints resisted by hydraulic rams, pumping high pressure oil through hydraulic motors via smoothing accumulators, ultimately driving induction machines </li></ul><ul><li>Power take off at each hinge </li></ul><ul><li>Power from all hinges fed into one sub-sea cable </li></ul>© Ocean Power Delivery http:// www.youtube.com/watch?v =F0mzrbfzUpM
    14. 15. Hydraulic Power Take Off
    15. 16. Aquamarine <ul><li>Hydro Technology </li></ul><ul><li>Pelton Turbine driving Synchronous Machine </li></ul>© Aquamarine
    16. 17. Oyster – Testing at EMEC © Aquamarine
    17. 18. Point Absorber: Archimedes Wave Swing © AWS BV Move with incident waves either in surge or heave mode and is very small compared to the wavelength.
    18. 19. AWS Electrical Power Conversion <ul><li>Linear PM synchronous machine </li></ul><ul><li>Rating – 2MW </li></ul><ul><li>Average – 400kW </li></ul><ul><li>Stroke – 4 to 7m </li></ul><ul><li>Velocity <= 2.2m/s </li></ul><ul><li>Double sided </li></ul><ul><li>Stator – 5.6m </li></ul><ul><li>Translator – 8.4m </li></ul><ul><li>Mass ? </li></ul>© AWS BV (Source: Dr. Henk Polinder, TU Delft)
    19. 20. Marine Current Turbines <ul><li>Axial flow turbine </li></ul><ul><li>SEAFLOW: 300 kW unit; Lynmouth, North Devon Coast </li></ul><ul><li>SEAGEN: 1.2MW, Strangford Narrows, N. Ireland </li></ul><ul><li>Power take-off by geared induction generator </li></ul>© Marine Current Turbines
    20. 21. Tidal Current Direct Drive: Open Hydro <ul><li>Rim Generator </li></ul><ul><li>Air-cored PM generator </li></ul><ul><li>Fully flooded </li></ul><ul><li>300kW device tested at EMEC </li></ul>
    21. 22. ScotRenewables <ul><li>Floating Turbine </li></ul><ul><li>Hydraulic Power Take Off </li></ul><ul><li>Induction Generator </li></ul>
    22. 23. Engineering Challenges <ul><li>Low speed </li></ul><ul><ul><li>Wind: 1MW – 20rpm, 7MW – 10rpm </li></ul></ul><ul><ul><li>Wave: recoprocating, 1-1.5 m/s peak </li></ul></ul><ul><ul><li>Tidal Current: 1MW – 10rpm </li></ul></ul><ul><li>Mechanical interface to step up speed </li></ul><ul><li>Direct Drive </li></ul><ul><ul><li>Physical size, weight, </li></ul></ul><ul><li>Permanent Magnet - Cost and Availability </li></ul><ul><ul><li>June £77/kg, August £150/kg </li></ul></ul><ul><li>Environment – corrosion, vibration </li></ul>
    23. 24. Engineering Challenge <ul><li>Variable prime mover </li></ul><ul><li>Wave: </li></ul>
    24. 25. Challenge Example - Oyster 6 m Diameter £ 3,182k Total Cost £ 116k Power Electronics Cost £ 3,066k Total Generator Cost 118,6 t Total Weight
    25. 26. Single Stage Gearbox <ul><li>Direct Drive </li></ul><ul><ul><ul><li>Maximum Reliability </li></ul></ul></ul><ul><ul><ul><li>Larger generator mass & cost </li></ul></ul></ul><ul><ul><ul><li>Low utilization of magnetic material (due to low speed) </li></ul></ul></ul><ul><li>Single Stage Gearbox </li></ul><ul><ul><ul><li>Reduced reliability (but not as multi speed gearboxes) </li></ul></ul></ul><ul><ul><ul><li>Decreased generator mass & cost </li></ul></ul></ul><ul><ul><ul><li>Increased efficiency & electricity generation </li></ul></ul></ul>
    26. 27. Designs with Different Gear Ratios
    27. 28. Integrated Design Wind speed distribution Wind turbine model Generator model Axial-flux Electrical model Structural model Criterion calculation Radial-flux 5 MW 3 MW 2 MW Thermal model
    28. 29. Hydrodynamic model Generator model Electrical model Structural model Criterion calculation Thermal model Design Optimisation Final Design Wave Energy Converter Wave Frequency Distribution
    29. 30. Structural Modelling of Direct Drive
    30. 31. What does this modelling tell us? <ul><li>Structural material is dominant </li></ul><ul><li>Optimal aspect ratios are larger </li></ul><ul><li>Optimal airgap lengths are larger </li></ul>Stator Rotor Stator Rotor
    31. 32. Structural Optimisation
    32. 33. Integrated Electromagnetic-Structural Optimization <ul><ul><li>A FEA optimisation tool was created to further decrease the weight of the direct drive generator </li></ul></ul><ul><ul><li>The FEA optimisation tool removes peaces of the predefined structure based on the major forces that apply on it </li></ul></ul><ul><ul><li>The rotating part was optimised separately from the stationery one </li></ul></ul><ul><ul><li>The new structures are up to 15% lighter compared to the original ones </li></ul></ul>Original Structure “ New” Structure Partial FEA Optimisation
    33. 34. Induction Generator Modelling for OWCs - Wavegen Airflow and generator power recorded during OWC operation Recorded casing and winding temperatures and 1 minute average generator power during operation
    34. 35. Solutions to Challenges <ul><li>Power Density or Mass </li></ul><ul><ul><li>Transverse Flux Machine </li></ul></ul><ul><ul><li>Air-cored Machines </li></ul></ul><ul><ul><li>Novel Structures </li></ul></ul><ul><ul><li>Superconducting Machines </li></ul></ul><ul><li>Low speed </li></ul><ul><ul><li>Magnetic Gearing - SNAPPER </li></ul></ul><ul><li>PM Magnets </li></ul><ul><ul><li>Switched Reluctance Machines </li></ul></ul>
    35. 36. Magnetic Gearing: SNAPPER Armature Translator Springs Copper Winding / Coil Stack Length, l s
    36. 37. F drive F spring F drive F spring Phase 1 Spring force is less than magnetic attraction force: Translator and armature move in same direction. Phase 2 Spring force matches magnetic attraction force: Armature movement ceases Phase 3 Armature becomes decoupled from translator and begins to move at high velocity relative to the translator.
    37. 38. Dry Testing
    38. 39. Dry Testing Video <ul><li>Dry Testing video </li></ul>
    39. 40. Economic – PM availability <ul><li>Switched Reluctance </li></ul><ul><ul><li>No permanent magnet material </li></ul></ul><ul><ul><li>Coils on stator only. </li></ul></ul><ul><ul><li>Rotor consists of iron laminations only. </li></ul></ul><ul><ul><li>Versatile in terms of control. </li></ul></ul><ul><ul><li>Requires grid connection for excitation </li></ul></ul><ul><ul><li>Small airgaps required for high performance. </li></ul></ul>
    40. 41. Experimental Prototype 20 kW at 100 rpm
    41. 42. Switched Reluctance with Segmental Rotor <ul><li>Prof Barrie Mecrow, University of Newcastle </li></ul>TOPOLOGIES FOR WOUND-FIELD THREE-PHASE SEGMENTED-ROTOR FLUX-SWITCHING MACHINES A. Zulu, B.C. Mecrow, M. Armstrong, IET PEMD, Brighton, 2010
    42. 43. Switched Reluctance with Segmental Rotor <ul><li>65% improvement in Torque Density (Nm/kg) compared conventional. </li></ul>“ Optimised Segmental Rotor Switched Reluctance Machines with a Greater Number of Rotor Segments Than Stator Slots” J.D. Widmer and B.C. Mecrow, IEEE IEMDC, Niagara, Canada, 2011 .
    43. 44. Transverse Flux Machines <ul><li>High Shear Stress at the airgap </li></ul><ul><ul><li>200kN/m 2 reported by Weh </li></ul></ul><ul><ul><li>4-5 times conventional PM synchronous machine </li></ul></ul><ul><li>Construction is challenging </li></ul><ul><li>Power Factor is an issue </li></ul><ul><ul><li>Surface mounted TFM – pf ~0.2 </li></ul></ul><ul><ul><li>Flux concentrating TFM - pf ~0.5 </li></ul></ul>
    44. 45. What type of TFPM machine ? A number of TFPM machine types have been proposed.  It is necessary to find the most suitable type. How?
    45. 46. Comparative design of PM machines a) RFPM machine b) TFPM machine-1 c) TFPM machine-2 d) TFPM machine-3 e) TFPM machine-4
    46. 47. Design parameters 12 Rotational speed, rpm 3 Number of phase, m 675 A Nominal current, i s 2746 V No-load voltage, e p 6.14 mm Air gap length, l g 6.14 m Air gap diameter, D g 5.56 MW Generator power, P Generator parameter 25 Magnet cost ( € /kg) 15 Copper cost ( € /kg) 3 Laminations cost ( € /kg) Cost modeling 0.025 Resistivity of copper at operating temperature (μΩm) 1.06 Recoil permeability of the magnets 1.2 Remanent flux density of the magnets (T) Material parameter
    47. 48. Comparison
    48. 49. Comparative design of PM machines a) RFPM machine b) TFPM machine-1 c) TFPM machine-2 d) TFPM machine-3 e) TFPM machine-4
    49. 50. PM Air-cored Machines <ul><li>Stator winding contains no iron. </li></ul><ul><li>Elimination of magnetic attraction forces between stator and PM rotor </li></ul><ul><li>Benefits in terms of </li></ul><ul><ul><li>Machine structural mass </li></ul></ul><ul><ul><li>Assembly and manufacture </li></ul></ul>
    50. 51. PM machines Copper Steel PM Stator Rotor Rotor <ul><li>Iron-cored machines: </li></ul><ul><ul><li>High flux density and shear stress </li></ul></ul><ul><ul><li>Large attractive forces between rotor and stator </li></ul></ul><ul><li>Air-cored machines: </li></ul><ul><ul><li>Lower flux density and shear stress </li></ul></ul><ul><ul><li>No attractive forces between rotor and stator </li></ul></ul>
    51. 52. Air cored PM: SLIM & Goliath
    52. 53. Goliath – 250kW <ul><li>Spoked Structure </li></ul><ul><li>Airgap Winding, steel surrounding winding </li></ul>
    53. 54. Open Hydro
    54. 55. Air-cored Machines:C-GEN
    55. 56. C-GEN modular assembly Rotor Stator Mild steel C-core Magnets
    56. 57. C-GEN final assembly <ul><li>PM Generators </li></ul><ul><ul><li>Assembly is difficult and dangerous </li></ul></ul><ul><ul><li>Large forces of attraction between rotor and stator </li></ul></ul><ul><li>C-GEN stator can be simply and easily lowered into place </li></ul><ul><ul><li>No forces </li></ul></ul><ul><ul><li>Assembles with an engine hoist </li></ul></ul><ul><ul><li>Production savings for large generators </li></ul></ul>
    57. 58. C-GEN Mk I: 20 kW Prototype Results Power 21.5 kW Outer radius 502 mm Efficiency 93 % Machine length 500 mm Speed 100 rpm Total mass 949 kg
    58. 59. C-GEN MkII: 15kW results rpm
    59. 60. Linear C-GEN for Wave <ul><li>50kW (pk) </li></ul><ul><li>Vpk = 2m/s </li></ul><ul><li>Machine Length = 3m </li></ul><ul><li>Stroke = 2m </li></ul>
    60. 61. High Temperature Superconducting Machines <ul><li>36.5 MW, 120 rpm (U.S. Navy, AMSC) </li></ul>American Superconductor Coorp
    61. 62. HTS Context <ul><li>Larger Offshore Wind Turbines (>5MW) </li></ul><ul><li>Gearboxes unfeasible </li></ul><ul><li>Direct Drive </li></ul><ul><ul><li>Low Speed – High Torque </li></ul></ul><ul><ul><li>More Reliable </li></ul></ul><ul><ul><li>High Generator Mass </li></ul></ul><ul><ul><ul><li>High Installation Cost </li></ul></ul></ul>M. Lesser, J. Müller, “Superconductor Technology – Generating the Future of Offshore Wind Power,”
    62. 63. Types of HTS Machines <ul><li>Rotating DC Superconducting Field </li></ul><ul><ul><li>Most Common Type </li></ul></ul><ul><ul><li>Transient Torques on HTS wire </li></ul></ul><ul><ul><li>Cryocooler Coupler + Brushes  Low Reliability </li></ul></ul><ul><ul><li>Cooling Times </li></ul></ul><ul><li>Magnetized Bulk HTS </li></ul><ul><ul><li>Very Difficult to Handle </li></ul></ul><ul><ul><li>Demagnetization </li></ul></ul><ul><li>All Superconducting Machines </li></ul><ul><ul><li>AC Losses on HTS wire </li></ul></ul>
    63. 64. HTS Machines – Claw Pole <ul><li>Stationary HTS coil to provide field excitation </li></ul><ul><li>Air-cored winding </li></ul><ul><li>Claw Pole Rotor </li></ul><ul><ul><li>steel construction </li></ul></ul><ul><ul><li>modulates the field </li></ul></ul>
    64. 65. Claw Pole HTS Generator
    65. 66. Future <ul><li>Low speed </li></ul><ul><ul><li>Direct Drive </li></ul></ul><ul><ul><li>Single Stage Gear Box </li></ul></ul><ul><li>Direct Drive </li></ul><ul><ul><li>HTS, Air-cored machines, Novel Support Structures </li></ul></ul><ul><li>Permanent Magnet Issue </li></ul><ul><ul><li>Switched reluctance segmented rotor machine </li></ul></ul><ul><li>Integrated Design Tools </li></ul><ul><ul><li>Electromagnetic, structural, thermo-fluid </li></ul></ul><ul><ul><li>Operational Environment </li></ul></ul><ul><ul><li>Design for Reliability </li></ul></ul>
    66. 67. Acknowledegements <ul><li>Scottish Enterprise </li></ul><ul><li>The Carbon Trust </li></ul><ul><li>npower juice </li></ul><ul><li>EPSRC Supergen Marine </li></ul><ul><li>EU FP6 UPWIND </li></ul><ul><li>EU FP7 SNAPPER Project </li></ul><ul><li>NGenTec </li></ul><ul><li>Fountain Design Ltd, TUV NEL, & Hopewell Wind Ltd </li></ul><ul><li>PhDs & RAs </li></ul><ul><ul><li>Ozan Keysan, Richard Crozier, Alasdair McDonald, Aris Zavvos </li></ul></ul><ul><li>Professor Ed Spooner (Goliath & Open Hydro) </li></ul><ul><li>Dr. Henk Polinder (TU Delft) </li></ul>

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