8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Eddy Current Distribution in Rotor ofPermanent Magnet Generators
using 3D Transient FEM
Hung Vu, PhD
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Outline
Geometry model,
3D transient Finite Element Model (FEM),
Rotor eddy current distribution during noload,
Rotor eddy current distribution due to current-carrying windings, and
Segmentation magnet to reduce eddy current
loss.
conclusion
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
@All rights reserved 3
Geometry Model
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Hung Vu
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3D Transient FEM Modeling
Hybrid between Scalar Magnetic Potential
and Vector Magnetic Potential
0 0
e
r
m
AH J
t
B A
H
H V
Governing equations of the magnetic field:
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Magnetic Fields in a Domain without
Currents using Scalar Magnetic Potential Vm
In magnetostatic problems where no electric currents
are present, it is possible to formulate and solve the
problem using a scalar magnetic potential.
In a current-free region: H= 0 (Amprs Law)
This implies that the magnetic scalar potential Vm canbe defined from the relation: H = Vm
Using the constitutive relation: B = 0rH+Br, the
equationB = 0 (Gauss Law) becomes:
0 0r mV rB
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Magnetic Fields in a Domain with Currents
using Vector Magnetic PotentialA
1 1
0
1 1
0
1 10
( ) , or
( ) , or
( ) ( )
( )
r
r
r
t
t
t
t
r e
r e
r e
e
AB B v B J
AB B v B J
AA B v A J
AJ v A J
where, Je
is an external current density, v is the velocity of
the conductor, is scalar electric potential, and J is total
current.
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Meshing
Tetrahedral meshes
8/11/2019 Eddy Current Distribution in Rotor of Permanent Magnet Generators using 3D Transient FEM
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Hung Vu
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Rotor eddy current distribution during noload
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Hung Vu
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Eddy Current in Rotor Yoke
During noload
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Hung Vu
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Magnet eddy current distribution due to
current-carrying windings alone
External current in windings
Magnet eddy current distribution
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Hung Vu
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Segmented magnets
3 segmentations in the
axial direction.3x3 segmentations.
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Reducing Eddy Current by using
Magnet Segmentations
Note: During noload, fully open slot, 3000 rpm.
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Hung Vu
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Comparison of 2D and 3D computation
20
125
25
100
0
20
40
60
80
100
120
140
1 3
Magnet segmentation number
Eddycurrentlossesinmagnets(W)
Fully-open slot, 3D
Fully open slot, 2D
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Hung Vu
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Video of eddy current
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