1 Design of Low Speed Axial Flux Permanent Magnet Generators for Marine Current Application Sanjida Moury Faculty of Engineering and Applied Science Memorial University of Newfoundland St. John’s, NL, A1B 3X5, Canada October 16, 2009 Supervised by Dr. Tariq Iqbal
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Design of Low Speed Axial Flux Permanent Magnet Generators for Marine Current
Application
Sanjida Moury
Faculty of Engineering and Applied Science Memorial University of Newfoundland
St. John’s, NL, A1B 3X5, CanadaOctober 16, 2009
Supervised byDr. Tariq Iqbal
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Presentation at a glanceObjectiveBackgroundDesign challengesFirst prototype
• Minimization of Cogging Torque TORUS ConfigurationTORUS configuration Alternating Pole ArcMagnet ShiftingFractional Number of Slots Per Pole
• Generator designRotorStatorStator winding
• Prototyped Generator• Test Result
Mechanical Parameter testElectrical parameter test
• System model
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Cont….
Second prototype• Generator Design
RotorStatorStator winding
• Prototyped Generator• Test Result
Mechanical Parameter testElectrical parameter test
• System modelComparison between two prototypeConclusionFuture workAcknowledgement
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ObjectiveTo extract few watts electrical power from the sea-floor ocean current.
To design a generator suitable for under water application.
To design a direct driven generator by eliminating step-up gearbox.
To design permanent magnet generators as a low speed energy converter.
Minimization technique1. Reducing the amplitude of each
portion2. Shifting the relative phase of the
different components
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Minimization of Cogging Torque (Cont….)
TORUS Configuration
(a) (b)
Figure 5: TORUS Topology (a) NN type and (b) NS type
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Minimization of Cogging Torque (Cont….)
Alternating Pole Arc
Figure 6(a): Same magnetpole arc
Figure 6(b): Different magnet Pole arc
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Minimization of Cogging Torque (Cont….)
Magnet ShiftingFractional Number of Slots Per Pole
Figure 7: Axial view of Rotor With Shifted magnet Figure 8: Two dimensional view
of shifted magnet
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Generator DesignRotor
Magnetic material- NdFeB
Number of pole- 100
Figure 9: Full and sectional view of Rotor
Large magnetLarge gap
Small magnetSmall gap
Steel ring
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Generator Design (Cont….)Stator
Slotted stator is build with ferrite E-cores.
Figure 10: (a) E-core (b) Stator
(a) (b)
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Generator Design (Cont….)
Stator Winding
Number of turns
ph
srms N
NfN
EE ××××== max
max
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2ϕπ
maxmax BAmagn ⋅=ϕ
)(max δ+⋅=
m
mr l
lBB
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Generator Design (Stator Winding) Cont…
Figure 11: Prototyped stator
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Generator Design (Stator Winding) Cont…
Figure 12: Stator winding
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Prototyped Generator
Figure 13: prototyped generator
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Test result
Mechanical Parameter test
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2mrJ =Rotor
F
r
m
Figure 14: Initial torque Measurement
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Test result (cont….)
Electrical parameter test
Figure 15: Test setup
Generator
Prime mover
OscilloscopeMultimeter
Load
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Test result (Electrical parameter test) cont….
Figure 16: Open Circuit voltage characteristic
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Test result (Electrical parameter test) cont….
Figure 17: Output Characteristic
Each graph shows the variation of generated power with rotational speed. The different graphs are for different load (2-20 ohm).
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Test result (Electrical parameter test) cont….
Figure 18:Load current and voltage characteristic
The graph shows the variation of load voltage with load current as load varies from 0-20 ohm. The different graphs arefor different frequencies.
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Test result (Electrical parameter test) cont….
Figure 19: Load characteristic
Each graph shows the variation of generated power with load. The different graphs are for different frequencies.
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Test result (Electrical parameter test) cont….
Figure 20: Voltage wave form
The voltage wave form for the both sides of the stator
Resultant wave form after connecting the both sides of the stator in series
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System model
Internal resistance, Rg
, [ohm] 1.8
Internal inductance, Lg
[µH] 216.7
Machine constant, λm 0.071
No load loss. Rnull
[ohm] 0.003f2+0.0116f-0.1458
Inertia, Jm
[Kg-m2] o.96
Initial torque, To [N-m] 14.5
Open Circuit voltage at 72 rpm [volt] 5.18
Load for maximum power point
[ohm]
1.8Figure 21: System model
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Conclusion
Output Power is 3.5 watt at 72 rpm.Open circuit voltage is 5.2 volt at designed speed.Generating current is high due to thicker wire.Cogging torque is minimized.Large in sizeMore frictional loss