() THE INSTITUTE OF ELECTRONICS, IEICE Technical Report INFORMATION AND COMMUNICATION ENGINEERS WPT2012-26(2012-11)
This article is a technical report without peer review, and its polished and/or extended version may be published elsewhere.
WPT
†1 † ‡2
†◊ 520-2194 1-5 ‡2194-520 1-5 REC
E-mail: 1 t090135@mail.ryukoku.ac.jp, 2 awai@ryutech.com
WPT(Wireless Power Transfer)






, ,
A Coupled Resonator WPT System Immune to Environmental Variations Yuichi SAWAHARA†1 Toshio ISHIZAKI† and Ikuo AWAI‡2
†Faculty of Science & Technology, Ryukoku Univ., 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga Pref. 520-2194 Japan ‡Ryutech Corporation, 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga Pref. 520-2194 Japan
E-mail: 1 t090135@mail.ryukoku.ac.jp, 2 awai@ryutech.com
Abstract Since a coupled-resonator wireless power transfer (WPT) system delivers energy via a coupled resonator system, the fluctuations of the resonant frequency of each resonator and the mutual coupling between them deteriorates the quality of energy transfer. The causes of those fluctuations are intrusion of alien matters into the transfer space and change of the space itself due to movement of the receiver or time lapses. Considering the electromagnetic property of the surrounding material is dielectric, one may attain the stable system by taking off the electric energy from the system.
First, we study the effect of share between the inductance and capacitance of the resonator with the constant resonant frequency. It is expected a larger capacitance will reduce the stray electric energy more. Secondly, each coil is separated into two to construct an effective capacitor between them. By reducing the distance between each coil, the electric energy around the coils decreases.
Keyword Wireless power transfer, Coupled resonator, Confinement of electric energy, Divided resonator, Dielectric
material .1










E0
H0
33
(1)
E1H1 E2H2
[3],[2]

⊃
/
⊃
0



(2) 0


↓ Q


1(a)

30cm 3cm
1(b) 2 r

(a)



1(c) (a) 2



20cm

1 2

2 1 3
[5],[4] 1(d) (c) 2


1.
3.

2







34


1MHz

2
23cm
1W
S11 -1dB

z=-10 10cm
3




4


75
0
50
100
150
200
250
Number of turns of coils

0
500
1000
1500
2000
2500
3000
3500


15


5


↓

6



22

0
50
100
150
200
250
300
350
400
450
500
-10 -8 -6 -4 -2 0 2 4 6 8 10


75turns
38turns
25turns
19turns
15turns
0
10
20
30
40
50
60
70
80
90
-10 -8 -6 -4 -2 0 2 4 6 8 10

75turns
38turns
25turns
19turns
15turns
20cm
30cm
9cm
10cm
20cm
30cm
9cm
10cm
35
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0 5 10 15 20 25 30 35 40 45
Number of turns of coils
S h if t
fr e q u e n c y

6.
3-2.
3-1



7 8 7
2mm 8
15


0
50
100
150
200
250
300
350
400
450
500
-10 -8 -6 -4 -2 0 2 4 6 8 10


15turns
18.7turns
25turns
0
10
20
30
40
50
60
70
80
90
100
-10 -8 -6 -4 -2 0 2 4 6 8 10


15turns
18.7turns
25turns
0 50
100 150 200 250 300 350 400 450 500
-10 -8 -6 -4 -2 0 2 4 6 8 10

1mm
2mm
5mm
10mm








9
10 20cm

0
0.0005
0.001
0.0015
0.002
0.0025
Distance between divided coils rt
S h if t
fr e q u e n c y




c
36





↓ Q
12
2
4 11
0
25

.11 L C MH
12. ↓ Q
↓ Q
↓
Q

2

↓ Q
↓ Q
7.5



WIPL-D 1W
S11 -1dB

30cm15 2mm

13



0
0.2
0.4
0.6
0.8
1
1.2
1.4
Relative permittivity


13.
. C




+
3cm
0
50
100
150
200
250
Distance between divided coils rt


0
500
1000
1500
2000
2500
3000
3500

22turns
Distance between divided coils rt


0
500
1000
1500
2000
2500
3000
3500

22turns
22turns
15turns
15turns
7.5turns
7.5turns
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25 Distance between divided coil rt
u n lo

1MHz
-1 C
14
15


0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
0.0018
0.002
Number of turns of the coils
S h if t
15.
4-2

16
17

15


L

Distance between divided coils ra
S h if t

17.
4-3 ↓ Q ↓ Q
18
↓ Q
↓
Q LC
11

Distance between divided coils ra
u n lo
18.↓ Q
↓ Q

20cm 3cm15
5cm15
Z
0cm
19 3cm

38
16 ↓



-90
-80
-70
-60
-50
-40
-30
-20
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1





5cm
3cm
-90
-80
-70
-60
-50
-40
-30
-20
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1





5cm
3cm

20 3cm
S21(Gain) -6.2dB 25%
5cm -2.4dB
↓58%

-60
-50
-40
-30
-20
-10
0
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1





5cm
3cm
-60
-50
-40
-30
-20
-10
0
0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1





5cm
3cm







Q

[1] R. F. Harrington, “Time-harmonic Electromagnetic
Fields”, McGraw-Hill Book Co., p.322, 1961 [2] Ikuo Awai, “ New expressions for coupling
coefficient between resonators ” , IEICE Trans. Electron., E88-C, No.12, pp.2295-2301, Dec. 2005.
[3] ,Vol.J89-C, pp.962-968 2006 12
[4] WPT WPT2012-202012 8
[5] “ WPT B-1-542012 9
39
40