superconducting rotating machines · 2018-11-21 · rotating magnetic field • basis for...
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Superconducting Rotating Machines
Bulk Superconductivity Group, Department of Engineering
Dr Mark Ainslie
EPSRC Early Career Fellow
EUCAS 2017 Short Course: Superconducting Power Applications
Geneva, 17 September 2017
Presentation Outline
• Electrical machines
• Three-phase & rotating fields
• Types of machines
• Synchronous, induction machines
• Superconducting electrical machines
• Case studies/examples with technical challenges & results
• Use of high temperature superconducting (HTS) conductors
• Use of bulk HTS materials
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines
• Electrical machines = motors & generators
• Motors: Convert electrical power mechanical power
• Generators: Mechanical power electrical power
• Huge range of sizes, power ranges & applications
• Sizes: Nanometres up to 10s of metres
• Power ranges: µW up to GW
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines
• Approx. one third of electricity consumed by industry [1]
• Approx. two thirds of this consumed by electric motors [2]
• Electric motors & systems they drive are the single largest
electricity end-use [3]
• 43-46% of global electricity consumption
• About 6 Gt of CO2 emissions
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[1] International Energy Agency, “2013 Key World Energy Statistics”, 2013
[2] ABB, “ABB drives and motors for improving energy efficiency,” 2010
[3] International Energy Agency, “Energy-Efficiency Policy Opportunities for Electric Motor Driven Systems,” 2011
[1] & [3] available from http://www.iea.org/publications/freepublications/
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Applications
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Washing machine
Hydroelectric generator
Extractor fan
Wind power generation
Computer fan
Synchronous generator Hobby motors
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines
• Generally operate via interaction of current-carrying conductors &
magnetic fields
• Various classifications based on how this interaction occurs:
• Alternating Current (AC) / Direct Current (DC)
• Synchronous machines
• Induction machines
• Hysteresis machines
• Switched reluctance machines
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines
• Generally operate via interaction of current-carrying conductors &
magnetic fields
• Various classifications based on how this interaction occurs:
• Alternating Current (AC) / Direct Current (DC)
• Synchronous machines
• Induction machines
• Hysteresis machines
• Switched reluctance machines
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Most widely used machines
Usually “three-phase AC”
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
• Three-phase is a common
method of AC electric power
generation, transmission &
distribution
• Economical & efficient polyphase
system
• Good compromise between
complexity, no. of conductors,
power transmitted & cost
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
• Allows generation of a rotating magnetic field
• Basis for three-phase generators & motors
• Balanced three-phase currents flowing in a balanced three-phase winding produce a rotating field of constant magnitude!
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
• Allows generation of a rotating magnetic field
• Basis for three-phase generators & motors
• Balanced three-phase currents flowing in a balanced three-phase winding produce a rotating field of constant magnitude!
Phase Angle (α) Current (I)
a 0° I cos ωt
b –120° I cos (ωt – 120°)
c –240° I cos (ωt – 240°)
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
• Allows generation of a rotating magnetic field
• Basis for three-phase generators & motors
• Balanced three-phase currents flowing in a balanced three-phase winding produce a rotating field of constant magnitude!
Phase Angle (α) Current (I)
a 0° I cos ωt
b –120° I cos (ωt – 120°)
c –240° I cos (ωt – 240°)
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Three-Phase Systems & Rotating Fields
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Synchronous Machines
• Synchronous machines
• MWs – 100s of MW, used in most large scale power generation, fixed
speed applications in mills, factories, etc.
• Rotor rotates in synchronism with line frequency/stator rotating field
• ns [rpm] = 60 f / p f = line frequency, p = no. of pole pairs
e.g., n = 60*50/1 = 3000 rpm
• Frequency of induced generator voltage ↔ rotor/machine rpm
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Synchronous Machines
• Synchronous machines
• Rotating rotor winding can be
• DC field winding = direct current (“excitation”) fed into winding
• Requires slip rings/brushes
• Can also use permanent magnets
• More costly (economics), but no slip rings/brushes required
(maintenance)
• Varying excitation for reactive power compensation not possible
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Synchronous Condensers
• Synchronous condensers
• Most industrial loads are inductive (“lagging”) by nature
• Draws excess current larger capacity equipment, more line
losses, penalties from electricity supply companies
• Varying excitation of rotor windings (under- or over-excited)
absorbs or supplies reactive power (VARs)
• Can drive the mechanical load & improve power factor*
*Power factor = ratio of real power to apparent power. A low power factor draws more
current for same amount of useful (real) power transferred.
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Electrical Machines – Induction Machines
• Induction (asynchronous) machines
• Induction motor is known as the “workhorse of industry”
• Simple construction, low cost, robust, variable speed possible, long operating lifetime
• Induction generators less utilised (lower efficiency)
• Used in wind turbines,small hydro power generation
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Induction Machines
• Rotor rotates asynchronously with stator rotating field
• Rotor can be wound or “squirrel cage”
• Slip, s = (ns – nr) / ns
• No load, nr ≈ ns
• Slip increases with load/torque
• Variable speed operation with power electronic control
• Torque-speed curves
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Induction Machines
• Rotor rotates asynchronously with stator rotating field
• Rotor can be wound or “squirrel cage”
• Slip, s = (ns – nr) / ns
• No load, nr ≈ ns
• Slip increases with load/torque
• Variable speed operation with power electronic control
• Torque-speed curves
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Electrical Machines – Induction Machines
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X1: stator leakage reactance
R1: stator winding resistance
RI: iron loss resistance
Xm: magnetising reactance
X2: rotor leakage reactance
(referred)
R2/s: rotor winding resistance
(referred)
Electromagnetic torque:
Maximise power
dissipated in
R2/s component
Torque-speed curves:
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
EUCAS 2017 Short Course: Superconducting Rotating Machinery B S G
Superconducting Electrical Machines
• Using superconductors can increase magnetic / electric loading of an electric machine
• Torque proportional to these + active volume
• Higher current density, higher magnetic field increased torque/power density reduced size & weight
• Lower wire resistance lower losses & higher efficiency / better performance
• Bulk superconductors >> permanent magnets
[1] S. Huang et al., “A General Approach to Sizing and Power Density Equations for Comparison of Electrical
Machines,” IEEE Trans. Ind. Appl. 34-1 (1998) 92-7
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
𝑃 =1
1 + 𝐾Φ
𝑚
𝑚1
𝜋
2𝐾𝑒𝐾𝑖𝐾𝑝𝜆0
2𝐵𝐴𝑓𝑚𝑒𝑐ℎ𝐷²𝐿𝜂
𝑃 =𝜋
2ത𝐵 ҧ𝐽𝐷2𝐿𝜔Synchronous (radial) machine
General machine
Superconducting Electrical Machines
• Over many decades, various superconducting machines shown to
be technically feasible over wide range of power ratings
• First attempted in the 1960s, replacing copper windings with LTS
• Improved efficiency (about 1%) was expected, but the main rationale
was the size/weight reduction
• Operated at liquid helium temperature (4 K)
• Complexity & cost of 4 K cryogenics prohibitive
• Large AC losses in armature winding unacceptable heat load
• Only DC field winding feasible
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
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ROTOR
Superconducting dc field winding (rotating)
External excitation current supply
Liquid helium coolant
High vacuum cryogenic insulation
Normally-conducting eddy current shielding system (conducting shell)
STATOR
Normally-conducting armature winding (stationary)
Cooling system rejecting heat at ambient temperature
Laminated back-iron flux shield
Optimal configuration for ac superconducting machines
from studies using LTS conductors in the 1960s & 70s
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
• Discovery of HTS materials in 1987 renewed enthusiasm!
• Expectation that materials could be exploited at higher temperatures,
e.g., 77 K
• Reduced capital costs for & complexity of refrigeration system
• Refrigeration efficiency ~100 times greater than at 4.2 K
• Carnot efficiency (ideal):
1 W heat = 2.8 W @ 77 K
68 W @ 4.2 K
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
• Discovery of HTS materials in 1987 renewed enthusiasm!
• Expectation that materials could be exploited at higher temperatures,
e.g., 77 K
• Reduced capital costs for & complexity of refrigeration system
• Refrigeration efficiency ~100 times greater than at 4.2 K
• Carnot efficiency (ideal):
1 W heat = 2.8 W @ 77 K
68 W @ 4.2 K
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
• Discovery of HTS materials in 1987 renewed enthusiasm!
• Expectation that materials could be exploited at higher temperatures,
e.g., 77 K
• Reduced capital costs for & complexity of refrigeration system
• Refrigeration efficiency up to 100 times greater than at 4.2 K
• Carnot efficiency (ideal):
1 W heat = 2.8 W @ 77 K
68 W @ 4.2 K
• Multiplication factor incl. cryocooler inefficiency: 20-50 @ 77 K
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
• Potential savings in weight / volume increased power / torque density
• Particularly attractive for applications where size / weight is a significant cost driver:
• Wind power generation, electric aviation, electric ship propulsion
• Advantages only appear over critical, “break-even” size or rating due to cryogenic system(s)
• I.e., where the refrigeration penalty (size, weight, cost) becomes negligible
• Critical / “break-even” size reduces with increasing operating temperature
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
• Discovery of HTS materials in 1987 renewed enthusiasm!
• Liquid nitrogen is inexpensive, inert, easy to use & store, readily
available
• Improved thermal properties:
• Assuming Cu stabiliser, specific heat increases
• Critical heat flux (nucleate film boiling) much higher for 77 K
than 4 K
• For 2G HTS (YBCO), improved in-field critical current density
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
In-Field Performance of Various Materials
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Data from NHFML: http://fs.magnet.fsu.edu/~lee/plot/plot.htm
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
– HTS Conductors –
EUCAS 2017 Short Course: Superconducting Rotating Machinery B S G
Superconducting Electrical Machines – AMSC
• American Superconductor (now AMSC) HTS ship propulsion motors
• U.S. Navy moving towards all-electric ship systems incl. propulsion
• Requirements difficult to achieve using conventional technology
• 2001-2004: 5 MW / 230 rpm [1]
• 2003-2008: 36.5 MW / 120 rpm [2]
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[1] G. Snitchler et al., IEEE Trans. Appl. Supercond. 15 (2005) 2206–2209.
[2] B. Gamble et al., IEEE Trans. Appl. Supercond. 21 (2011) 1083–1088.
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines – AMSC
• ROTOR (AMSC)
• HTS field winding at 32 K
• BSCCO-2223 (1G) wire
• Helium gas cooled, external cryocooler module
• EM shield
• STATOR (ALSTOM)
• Dielectric oil cooled Litz wire
• Air-gap winding, non-magnetic support structure
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines – AMSC
• Rotor integrated with stator at Alstom for full factory testing (2003)
• Full load, full speed testing completed
• Operated for 21 hours at Center for Advanced Power Systems, FSU (2005)
• Achieved specified performance & power ratings under full operating conditions
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5 MW, 230 rpm HTS Motor (left)
with 2.5 MW load motor (right)
at ALSTOM, UK
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines – AMSC
• Extended to 36.5 MW HTS motor
• 14:1 increase in torque over 5 MW machine
• Passed full power tests by end of 2008
• Achieved specific target of 75 metric tonnes
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1/2 size
1/3 weight
of traditional copper-based
propulsion systems
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines – Other Efforts
• Japanese Super-GM program, 70 MW-class superconducting generators (LTS)
• AMSC developed a 8 MVAR (1800 rpm) synchronous condenser
• Siemens 380 kW (1500 rpm) motor, extended to a 4 MVA (3600 rpm) generator
• Sumitomo Electric 30 kW motor for electric passenger car
• Converteam 1.7 MW (214 rpm) hydroelectric power generator
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SIEMENS SUMITOMO CONVERTEAM
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Induction Machine
• High temperature
superconducting induction-
synchronous machine (HTS-ISM)
• Developed at Kyoto University
• Target: electric vehicle drive motor
• Replace rotor windings of squirrel
cage induction machine with HTS
materials
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Induction Machine
• Current induced in rotor
winding at slip frequency, sf
• s = 1 (standstill)
s 0 (near synchronous speed)
• Large current induced when
starting
flux-flow resistivity (E/J)
large starting torque
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Test bench for Kyoto University’s
HTS-ISM, including load
(permanent magnet) motor
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Induction Machine
• Current induced in rotor
winding at slip frequency, sf
• s = 1 (standstill)
s 0 (near synchronous speed)
• Large current induced when
starting
flux-flow resistivity (E/J)
large starting torque
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Induction Machine
• As motor accelerates, s and rotor resistance reduces
small resistance at low slip
• At s = 0, magnetic flux linked between rotor bars is trapped(induced persistent current)
synchronous torque at zero slip
• Hence, coexistence of synchronous and slip modes
robust against overload conditions, dynamic switching between modes
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
– Bulk Superconductors –
EUCAS 2017 Short Course: Superconducting Rotating Machinery B S G
Bulk High Temperature Superconductors
• Can be utilised in machines in three ways:
• Flux shielding (reluctance)
• Flux pinning (hysteresis)
• Flux trapping (trapped flux)
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A large, single grain
bulk superconductor
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• RELUCTANCE MOTOR
• Difference in permeability in direct (‘easy’ path) & quadrature (‘difficult’)
• Rotor aligns itself with direct axis
• Torque, T, proportional to difference of flux in direct & quadrature axes
• T, SC machine > conventional machine (magnetic & non-magnetic interleaving)
B S GBarnes et al. Supercond. Sci. Technol. 13 (2000) 875-878
d axis
q axis
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• RELUCTANCE MOTOR
• Based on flux shielding property
• Combines bulk SC + ferromagnetic material
• Bulk SC shields flux, reinforcing ferromagnetic material
• Can show flux pinning / hysteresis motor-like behaviour
• Disadvantages
• Increase in torque only up to + ~1/3 of conventional
• Use of iron limits flux density < 2 T; usually much less than, but up to 1 T air gap field
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Kovalev et al. Supercond. Sci. Technol. 15 (2002) 817-822
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• HYSTERESIS MOTOR
• Based on flux pinning property
• Normal hysteresis motor has ferromagnetic rotor torque produced by interaction between stator/driving field + magnetisation of rotor by this field
• Like induction motor, ‘slippage’ (lag) between driving field & rotor
• Lag independent of speed, so constant torque from start-up to synchronous speed
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• HYSTERESIS MOTOR
• Type II superconductor exhibits magnetic hysteresis = pinned flux lines
• Approaching synchronous speed/steady state, behaves like synchronous motor
• Main magnetic field must be produced by stator windings
• Low operating power factor, efficiency, torque density
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• Conventional magnets (NdFeB, SmCo) limited by material properties
• Magnetisation independent of sample volume
• Bulk HTS “trap” magnetic flux via macroscopic electrical currents
• Magnetisation increases with sample volume
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A large, single grain
bulk superconductor
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk High Temperature Superconductors
• Conventional magnets (NdFeB, SmCo) limited by material properties
• Magnetisation independent of sample volume
• Bulk HTS “trap” magnetic flux via macroscopic electrical currents
• Magnetisation increases with sample volume
• Trapped field given by
Btrap = k µ0 Jc a
a = radius; k = geometric constant (Biot-Savart law)
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Typical trapped magnetic
field profile above a
bulk superconductor
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk HTS Trapped Fields
• Trapped field measurements tell us the potential of a sample as a strong, permanent magnet
• Demonstrated trapped fields over 17 T
• 17.24 T at 29 K
2 x 26.5 mm YBCO
Tomita, Murakami Nature 2003
• 17.6 T at 26 K
2 x 25 mm GdBCO
Durrell, Dennis, Jaroszynski, Ainslie et al.
Supercond. Sci. Technol. 2014
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk HTS Trapped Fields
• Significant potential at 77 K
• Jc = up to 5 x 104 A/cm2 at 1 T
• Btrap up to 1 ~ 1.5 T for YBCO
• Btrap > 2 T for (RE)BCO,
neutron-irradiated YBCO
• Record trapped field = 3 T at 77 K
• 65 mm GdBCO
• Nariki, Sakai, Murakami Supercond. Sci.
Technol. 2005
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Rotating Machines Using Bulk HTS
Comparison of radial
and axial machines
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Radial-type bulk machine
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Rotating Machines Using Bulk HTS
Comparison of radial
and axial machines
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Axial-type bulk machine
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Bulk HTS Axial Flux Motor
• Axial gap, trapped flux-type motor
• Advantages:
• Higher torque/power density
• Compact ‘pancake’ shape
• Better heat removal
• Adjustable air gap
• Multi-stage machines possible
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TUMSAT* prototype motor
for ship propulsion
EUCAS 2017 Short Course: Superconducting Rotating Machinery
*Izumi et al. Tokyo University of Marine Science and Technology (TUMSAT)
Bulk HTS Axial Flux Motor
• Uses stator coils to magnetise HTS bulks with pulsed field
• Cooled using liquid nitrogen
• Dual purpose: magnetising coils, then armature winding
• Closed cycle neon thermosyphon system
• Includes cryo-rotary joint
• Cryogen from static condenser to rotating rotor plate with bulk HTS
• Allows cooling of bulks HTS down to below 40 K
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Schematic diagram of
TUMSAT prototype motor
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Magnetisation of Bulk Superconductors
• Three magnetisationtechniques:
• Field Cooling (FC)
• Zero Field Cooling (ZFC)
• Pulse Field Magnetisation(PFM)
• To trap Btrap, need at least Btrapor higher
• FC and ZFC require large magnetising coils
• Impractical for applications/devices
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ZFC FC
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Pulsed Field Magnetisation
• PFM technique: compact, mobile, relatively inexpensive
• Issues: Btrap [PFM] < Btrap [FC], [ZFC]
• Temperature rise ΔT due to rapid movement of magnetic flux
• Record PFM trapped field: 5.2 T @ 29 K
Top surface of 45 mm diameter Gd-Ba-Cu-O
Fujishiro et al. Physica C 2006
• Record trapped field by FC: 17.6 T @ 26 K
Centre of 2 x 25 mm diameter Gd-Ba-Cu-O
Durrell et al. Supercond. Sci. Technol. 2014
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Pulsed Field Magnetisation
• Many considerations for PFM:
• Pulse magnitude, pulse duration, temperature(s), number of pulses,type of magnetising coil(s), use of ferromagnetic materials
• Dynamics of magnetic flux during PFM process
• Multi-pulse PFM: effective in increasing trapped field/flux
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Fujishiro et al. Physica C 2006 Zhou et al. Appl. Phys. Lett. 2017
EUCAS 2017 Short Course: Superconducting Rotating Machinery
Superconducting Electrical Machines
– Future Outlook –
EUCAS 2017 Short Course: Superconducting Rotating Machinery B S G
Future Views & Prospects
• Significant body of work 2G HTS (RE)BCO coated conductor, MgB2
• Most designs have focused on isolated, cryogenic rotor + conventional stator
• Low ac loss conductor and/or improved winding/machine design
• All-cryogenic / all-superconducting solutions with unprecedented power densities
• Will reduce complexity, improve reliability
• Cost still a major issue as identified by large-scale projects
• Appropriate infrastructure & knowledge required for large-scale manufacture
• Superconducting materials & cryogenic/vacuum systems need to be available on an industrial level
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Future Views & Prospects – Bulk-based Machines
• Magnetisation techniques
• Improved in-situ PFM 5-7 Tesla trapped fields
• Magnetic field stability + demagnetisation
• Time-varying fields in real machine environments demagnetisation?
• Mechanical properties of bulks + mechanical design of machines
• Limiting factor for very high field applications (> 7-9 T); brittle ceramics
• Development of numerical models
• Crycooler + cryostat technology
• Efficiency, reliability, cost, redundancy; complete engineering solution required
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Recommended Further Reading
• Superconductor Science & Technology‘Focus Issue on Superconducting Rotating Machines’ (2016)
• Novel topologies (claw-pole, homopolar machines)
• Wind turbines (MgB2 field winding & ac loss analysis)
• Bulk-based machines (TUMSAT review)
• HTS stator (BSCCO) thermal analysis
• Brushless HTS-PM exciter for rotating DC field winding (flux pump)
• Magnetic gears (HTS conductors)
Available online: http://iopscience.iop.org/0953-2048/focus/Focus-on-Superconducting-Rotating-Machines
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Recommended Further Reading
• J. R. Bumby, “Superconducting rotating electric machines (monographs in electrical and electronic engineering),” Oxford: Clarendon Press (1983)
• K. S. Haran et al., “High Power Density Superconducting Machines – Development Status and Technology Roadmap,” Supercond. Sci. Technol. (accepted for publication)
• http://iopscience.iop.org/article/10.1088/1361-6668/aa833e
Bulk-based machines:
• D. Zhou et al., “An overview of rotating machine systems with high-temperature bulk superconductors,” Supercond. Sci. Technol. 25 (2012) 103001
• http://iopscience.iop.org/article/10.1088/0953-2048/25/10/103001/meta
• Y. Zhang et al., “Melt-growth bulk superconductors and application to an axial-gap-type rotating machine,” Supercond. Sci. Technol. 29 (2016) 044005
• http://iopscience.iop.org/article/10.1088/0953-2048/29/4/044005/
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery
Presentation Outline
• Electrical machines
• Three-phase & rotating fields
• Types of machines
• Synchronous, induction machines
• Superconducting electrical machines
• Case studies/examples with technical challenges & results
• Use of high temperature superconducting (HTS) conductors
• Use of bulk HTS materials
B S GEUCAS 2017 Short Course: Superconducting Rotating Machinery