A micro flywheel energy storage system with a high-temperature superconductor (HTS) bearing which is characterized by the diamagnetic effect and the flux pinning effect has been developed. The micro flywheel is made up of circumferential magnets for a motor/generator as well as concentric magnets for an HTS bearing and they are fitted into a 34-mm diameter and 3-mm thick aluminum disk. Mass and moment of inertia of the micro flywheel are 12.75 g and 1.84E−6 kgm2, respectively. For simplicity and miniaturization of the whole system, the micro flywheel directly takes torque from a planar stator, which consists of an axial flux type brushless DC motor/generator. The micro flywheel successfully rotated up to 38,000 rpm in vacuum condition as it is levitating above the stator with a gap of about 1 mm. However, there are some eddy current losses in the stator and non-axisymmetry in magnetic field causing large drag torque. In order to solve these problems, an improved magnet array in the flywheel including a Halbach array is proposed and 3D simulations have been conducted.

1.
John
R Hull
,
2000
, “
Topical Review: Superconducting bearings
,”
Superconductor Science and Technology
,
13
,
R1–R15
R1–R15
.
2.
Nagaya
S.
,
Kashima
N.
,
Minami
M.
,
Kawashima
H.
,
Unisuga
S.
, March
2001
, “
Study on High Temperature Superconducting Magnetic Bearing for 10KWh Flywheel Energy Storage System
,”
IEEE Transactions on Applied Superconductivity
, Vol.
11
, No.
1
,
1649
1652
.
3.
Day
A. C.
,
Strasik
M.
,
McCrary
K. E.
,
Johnson
P. E.
,
Gabrys
J. W.
,
Schindler
J. R.
,
Hawkins
R. A
,
Carlson
D. L.
,
2002
, “
Design and testing of the HTS bearing for a 10kWh flywheel system
,”
Superconductor Science and Technology
,
15
,
838
841
.
4.
T.H. Sung, J.S. Lee, Y. H. Han, S.C. Han, S.K. Choi, S.J. Kim, 2002, “300 Wh class superconductor flywheel energy storage system with a horizontal axle,” Physica C, 372–376, 1451–1456.
5.
Mulcahy
T. M.
,
Hull
J. R.
,
Uherka
K. L.
,
Niemann
R. C.
, June
1999
, “
Flywheel Energy Storage Advances Using HTS Bearings
,”
IEEE Transactions on Applied Superconductivity
, Vol.
9
, No.
2
,
297
300
.
6.
Coombs
T. A.
,
Cansiz
A.
and
Campbell
A. M.
,
2002
, “
A superconducting thrust-bearing system for an energy storage flywheel
,”
Superconductor Science and Technology
,
15
,
831
835
.
7.
Lee
E.
, June
2003
, “
A Micro HTS Renewable Energy/Attitude Control System for Micro/Nano Satellites
,”
IEEE Transactions on Applied Superconductivity
, Vol.
13
, No.
2
,
2263
2266
.
8.
Wilson
T. L.
, June
2003
, “
A High-Temperature Superconductor Energy-Momentum Control System for Small Satellites
,”
IEEE Transactions on Applied Superconductivity
, Vol.
13
, No.
2
,
2287
2290
.
9.
Hull
J. R.
,
Mulcahy
T. M.
,
Uherka
K. L.
, June
1995
, “
Low Rotational Drag In High-Temperature Superconducting Bearings
,”
IEEE Transaction on Applied Superconductivity
, Vol.
5
, No.
2
,
626
629
.
10.
Kordyuk
A. A.
,
Nemoshkalenko
V. V.
, June
1997
, “
High-Speed Magnetic Rotor with HTS Bearings for Precision Energy Losses Investigation
,”
IEEE Transaction on Applied Superconductivity
, Vol.
7
, No.
2
,
928
931
.
11.
Niknejad
A. M.
,
Meyer
R. G.
, January
2001
, “
Analysis of Eddy-Current Losses Over Conductive Substrates with Applications to Monolithic Inductors and Transformers
,”
IEEE Transaction on Microwave Theory and Techniques
, Vol.
49
, No.
1
,
166
176
.
12.
Lee
E.
,
Kim
B.
,
Ko
J.
,
Song
C. Y.
,
Kim
S. J.
,
Jeong
S.
, and
Lee
S. S.
,
2005
, “
An Integrated Micro HTS System for Energy Storage and Attitude Control for Three-Axis Stabilized Nanosatellites
,”
IEEE transactions on applied superconductivity: a publication of the IEEE Superconductivity Committee
, Vol.
15
, No.
2
, pt.2,
2324
2327
.
This content is only available via PDF.
You do not currently have access to this content.