1 jun watanabe 2015.6.29 r&d status of highly efficient stirling-type cryocooler for...
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1Jun Watanabe 2015.6.29
R&D status of highly efficient Stirling-type cryocooler for superconducting drive motor
J Watanabe, T Nakamura, S Iriyama,
T Ogasa, N Amemiya(Kyoto University, Japan);
Y Ohashi(AISHIN SEIKI Co.,Ltd , Japan)
CEC/ICMC 2015
June 29-July 4 2015
JW Marriott Starr Pass Resort & Spa,
Tucson, Arizona
Outline
1. Background and objective
2. Specifications of developed compressor
3. Analytical and experimental method
4. Results and discussion
5. Development and test of pulse-tube cryocooler
6. Conclusion
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3Jun Watanabe 2015.6.29
1. Background and objective
Advantages・ High efficiency thanks to synchronous rotation・ High torque density・ Stable Rotation
High Temperature Superconductor Induction/Synchronous Machine
HTS-ISM
Target ;Drive motor for the next generation electric vehicle
Direct-drive without transmission gears
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Fig.1 Schematic diagram of direct-derived power train system
インバータバッテリー
制御ユニット
小型冷凍機
HTS-ISM
インバータバッテリー
制御ユニット
小型冷凍機
HTS-ISMHTSISM
InverterBattery
Controlunit
Cryocooler
1. Background and objective
Necessary functions of the cryocooler for HTS-ISM system
・ High efficiency ・ Light weight・ Robustness against vibration
Development of highly efficient Stirling-type cryocooler
Development of linear actuator-type compressor
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Input 3000 W
Coil Wire diameter 1.6 mm
Turn number of coil 210
DC resistance 0.6 Ω
Rated stroke length ±10 mm
Piston diameter 40 mm
Table1 Specifications of compressor
Fig.2 Schematic diagram of compressor
Outer yokeInner yoke
Compression zone
Piston
Flexure bearingPermanent magnet
Coil
Moving magnet type linear actuator
2. Specifications of the developed actuator
Outer yoke
Coil
Shaft
Permanent magnet
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Finite element method analysis model
SN
SN
x
r
Analysis by commercial software(JMAG-Designer )Ⓡ
Stator
(Analysis conditions) External circuit : Single-phase current source Mover motion : Forced displacement
Inner yoke
Fig.3 Axisymmetric analysis model of the linear actuator
3. Analytical and experimental method
Mover
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Non-linear spring characteristic of the flexure bearingOrifice effect between
piston and cylinderα
Pressure changes in Stirling-cycle space
Dumping of the drive coilRigidity of the electromagnetic force….etc
tnaxxfxfxfdt
dxx
dt
xdm
nn sin))()()(())(( 3212
2
)(1 xf
)(2 xf
)(),( 3 xfx
Mover(piston+motor)
Electrical input :Sinusoidal wave
Fig.4 Analysis model of the actuator
Electromagnetic field analysis code coupled with kinetic equation
3. Analytical and experimental method
3. Analytical and experimental method
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8
Experimental method under no-load condition
Fig.5 Schematic diagram of experiment under no-load condition
Fig.6 Photograph of compressor assembly
1Φ 200 V
Laser displacement Compressionzone
Linear actuatorLinear actuator Laser displacementsensor
Voltage controledinverter
sensor
Voltage controlled inverter
Compression - zone
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Pressure gaugeNeedle valve
Laser displacement sensor
Buffer tank
Load test of the compressor with He gas
Fig.7 Photograph of experimental system under load condition V
P
0Fig.9 PV work
Fig.8 Laser displacement sensor
Pressure
Volume
3. Analytical and experimental method
10
(c) Current(a) Displacement
xa=5 mm
(b) Voltage
xa=10 mm
Drive frequency 42 Hz, Displacement 5 mm, 10 mm (experimental results)
In case of xa=10 mm, the current waveform was distorted.
Detailed examination by analysis
The power factor was decreased because phase of the current waveform lagged.
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4. Results and discussion
Fig.10 Experimental results under no-load condition
11
0
1
2
3
4
5
0 42 84 126 168 210 252
xa =1.55 mmxa =3.34 mmxa =5.06 mmxa =6.88 mmxa =8.65 mmxa =10.1 mm
Cu
rre
nt I
(A
)
Frequency f (Hz)
Fig.11 Power spectrum of current waveform
The FFT analysis of the current waveform →Third harmonic component was highly included
Current waveform obtained by superimposing the third harmonic
0
50
100
150
200
250
0 2 4 6 8 10 12
MeasuredAnalyzed (fundamental wave)Analyzed (harmonic wave)
Eff
ect
ive
po
we
r P
(W
)
Displacement amplitude xa (mm)
0
20
40
60
80
100
120
0 2 4 6 8 10 12
MeasuredAnalized (fundermental wave)Analized (harmonic wave)
Vo
ltag
e V
(V
)
Displacement amplitude xa (mm)
(a) Effective power (b) Voltage
Agreement between experimental and analysis results
Reason for the current waveform distortion
Fundamental only
Third harmonic superimposed
Fig.12 Experimental and analysis results under no-load condition
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4. Results and discussion
12
-200
-150
-100
-50
0
50
100
150
200
0 0.005 0.01 0.015 0.02 0.025
xa =1.55 mmxa =3.34 mmxa =5.05 mmxa =6.88 mmxa =8.65 mmxa =10.1 mm
I
Co
unt
er
elec
trom
otiv
e f
orce
Es
(V)
Time t (s)
Fig.13 Analysis results of counter-electromotive force
(a) Waveform (b) Effective value
The counter-electromotive force in the case of forced displacement (analysis results)
→ Distortion of the waveform caused by nonlinear B-H curve
0
20
40
60
80
100
0 2 4 6 8 10 12
Co
unte
r e
lect
rom
otiv
e fo
rce
Es
(V)
Displacement amplitude xa (mm)
Out of the linearDistortion
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4. Results and discussionC
ou
nte
r-e
lect
rom
otiv
e f
orc
e E
s
(V)
Co
un
ter-
ele
ctro
mo
tive
fo
rce
Es
(V)
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0
1000
2000
3000
4000
5000
6000
0 5 10 15 20
Input powerMechanical output
Po
wer
P (
W)
Current I (A)
0
0.2
0.4
0.6
0.8
1.0
0 5 10 15 20
EfficiencyPower factor
Current I (A)
Output characteristics (analysis results)
Fig.14 Output characteristics (analysis results)
→ Possibility of high efficiency and power factor
Displacement 10.0 mm, Frequency 58 Hz, Current - displacement phase difference 90 °
4. Results and discussion
Mechanical output2495 W
Efficiency 90 %
Power factor 0.83
Po
we
r P
(W
)
200
400
600
800
1000
1200
Effective power
Work
Pow
er P
(W)
small largeValve aperture
Frequency 59 Hz Pressure 2.5 MPa Input 200 V
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Fig.15 Experimental results under load condition
(a) Input power and PV work (b) Displacement
(c) Efficiency and power factor
Next target: ・ Improvement of efficiency
0
0.2
0.4
0.6
0.8
1
Efficiency
Power factor
small largeValve aperture
・ Comparison of analysis results
4. Results and discussion
3
4
5
6
7
8
Displacement (left)
Displacement (right)
Dis
pla
cem
ent
x(m
m)
small largeValve aperture
・ Test at the rated displacement
Po
we
r P
(W
)
Dis
pla
cem
en
t x
(m
m)
5. Development and test of the pulse-tube cryocooler
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z
Heat exchanger
Cold stage
Pulse-tube
Hot stage
Fig.16 Photograph of pulse-tube cryocooler
Cooling test of the pulse-tube cryocooler coupled with the compressor
sensor
Heat exchanger
1Φ 400 V
Laser displacement
Buffer tank
Copper pipe
Compressionzone Linear actuatorLinear actuator
Laser displacement
sensor
sensorPressure
Variable voltageinverter
Cold stage
Pulse tube
sensor
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Buffer tank volume
3485 cm3
(1 gal)
Copper pipe length
2 m
Evaluation of pulse-tube cryocooler at 77 K
Fig.17 Schematic diagram of experiment of pulse-tube cryocooler
Table2 Specifications of buffer unit
5. Development and test of the pulse-tube cryocooler
Voltage controlled inverter
Compression - zone
Pressure 2.5 MPa, Input 160 V, Operational temperature 77 K
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Fig.18 Experimental results of pulse-tube cryocooler
Output 31.603 W COP 0.0276
(a) Input power and PV work (b) Cryocooler output (c) COP
Next target: Re-try of cooling test with the improved compressor
0.01
0.015
0.02
0.025
0.03
48 49 50 51 52 53 54 55
COPCO
P
Frequency f (Hz)
15
20
25
30
35
48 49 50 51 52 53 54 55
Heater output
Po
we
r P
(W
)
Frequency f (Hz)
0
200
400
600
800
1000
1200
1400
48 49 50 51 52 53 54 55
Effective powerWork
Po
we
r P
(W
)
Frequency f (Hz)
5. Development and test of the pulse-tube cryocooler
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6. Conclusion
・ Development of linear actuator-type compressor for cryocooler
・ Agreement between experimental and analytical results by considering the nonlinear B-H curve of the iron core
・ Modeling the linear actuator by the use of electromagnetic field analysis code coupled with kinetic equation
・ Obtaining analytical results which show possibility of high efficiency as well as high power factor
・ Conducting cooling test of the pulse-tube cryocooler
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Future plan
・ Experiment at the rated displacement and development of analysis code considering thermodynamics of He gas ・ Development of Stirling-type cryocooler for HTS-ISM system
6. Conclusion