THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE Mar.; 25(3),

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1 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE Mar.; 25(3), ISSN (Print)ISSN X (Online) Analysis of Magnetically Coupled Wireless Power Transmission Efficiency according to Material 오택규 이범선 TaekKyu OhBomson Lee 요약 ()(k) Q (R L,opt )(SRR RR),, Relay. Case 1160 %., EM. Abstract This paper presents the analysis of the coupling coefficient(k), Q value of the resonator, and the optimum loaded resistance at Rx for the magnetically coupled wireless power transmission using two loops(resonators). In addition, the metamaterial, conductor, and the relay methods have been used in order to improve the limitation problem of transmission efficiency by using the figure of merit. We have achieved the increase of transmission efficiency about 1160 % using the proposed methods by analyzing and comparing the results based on EM simulations. Key words: Coupling Coefficient, Firgure Of Merit, Magnetic Coupling, Wireless Power Transmission. 서론. 1914(Nikola Tesla) [1]., MIT (Marin Soljacic). (KCA ). (Department of Electronics & Radio Engineering, Kyung Hee University) Manuscript received December 6, 2013 ; Revised March 7, 2014 ; Accepted March 11, (ID No S) Corresponding Author: Bomson Lee ( bomson@khu.ac.kr) 304 c Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved.

2 [2].,. [3][8].., (η L )(k) Q (R L ), [5]. (R L,opt ) (η L ) EM.. 자계결합방식무선전력전송분석 1 2. ( 1),, (magnetic flux) ( 2)., 2( ). 2, 1 그림 2. Fig. 2. Equivalent circuit of magnetic coupled wireless power transmission considering radiation loss.. 2, (). 1 2 r 1, r 2, r ring1, r ring2. V, R L 2. C 1 C 2, 1 1, P loss1 P loss2, P rad1 P rad2. d. R l1, R l2, R r1, R r2. L 1 L 2. M, k(l 1 L 2 ) 1/2, I 1 I 2. Quality factor Q 1, Q 2 ω 0 L 1 / R 1, ω 0 L 2 / R 2, η L (1) [6]. (1), F m (Figure of merit) (2). 그림 1. Fig. 1. Structure of designed loop antenna and magnetic coupled wireless power transmission system. (2) x 2 R L (R L,opt ). 305

3 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 3, Mar 그림 3. kq Fig. 3. WPT efficiencies as a function of kq. (3) (R L,opt ) (4). x=1(r L =R L,opt ). 3 x. 2 R L R L,opt., kq=10, R L 10 % (x=100, 0.01) 80 % (x=1). R L [5]. F m. F m EM.. 삽입되는물질에따른자계결합방식의무선전력전송시스템의전송효율 4 (a). 1, 2(r 1 ) 5.5 cm, MHz, Q 473, (d) 24 cm, 278 nh, (4) (a) (a) Focusing system (b) Relay (b) Relay system 그림 4. (r=5.5 cm, d=24 cm, f 0 =13.56 MHz) Fig. 4. Application of WPT system. 표 1. (η L ). (r=5.5 cm, d=24 cm, a=b=6 cm, s=12cm, f 0 =13.56 MHz) Table 1. WPT efficiencies as a function of material. μ r =1 η L [%] (R L =R L,opt ) 32 % (0.1 Ω) μ r =1 () 98 % (17 Ω) μ r =1 j % (7 Ω) μ r =1 j0.23 s=6 cm 46.6 % (0.2) Resonator 98 % (5 Ω) 496 pf. s=12 cm, a=b=6 cm., [5]. 4(b) 1, 2 (a=b=11 cm). 1 4(a) (b) (η L ) HFSS EM. (μ r =1) 98 %., (tanδ), 20 % 12 %. 5(a) (s) 306

4 (a) (a) WPT efficiencies as a function of width 5(b) EM slab EM S-parameter., MHz. Relay 98 %., (tanδ) [8].,. 4.. 주변물질에따른자계결합방식의무선전력전송시스템의전송효율 (b) S-parameter (b) Result of S-parameter 그림 5. S-parameter. (r=5.5 cm, d=24 cm, a=b=6 cm, s=12 cm, f 0 =13.56 MHz) Fig. 5. WPT efficiencies as a function of width an S-parameter. static field slab 1, (d) slab (s). statics field quasi-statics field, (tanδ) slab [7] MHz. (r) 5.5 cm, Q 255, (L) 278 nh MHz (C=1,950 pf). (d) 24 cm, (w) 1 cm.. 2. Case 1, Case 2 (η L ) EM. 1() 22 %. 1() 22 %. 10() Case 1, 2, 307

5 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 3, Mar (a) Case 1 (b) Case 2 그림 6. (r=5.5 cm, d=24 cm, w=1 cm) Fig. 6. WPT system with a magnetic material. 표 2. (η L ) (R L =R L, opt ) Table 2. Maximum WPT efficiency by magnetic material. μ r j0.2 10j0.6 PMC Case 1 Case 2 22 % (0.1 Ω) 33.3 % (0.09 Ω) 49.2 % (0.11 Ω) 15.1 % (0.2 Ω) 11 % (0.2 Ω) 9 % (0.4 Ω) 3.4 % (0.4 Ω) 40 % (0.08 Ω) 68 % (0.09 Ω) 그림 8. Case 2 H-field Fig. 8. Magnitude of H-field in Case 2. 표 3. (η L )[%] Table 3. WPT efficiency by the conductor. 1 Copper μ r =0 μ r =0j 1 η L (%) (R L =R L,opt ) 22 % (0.1Ω) 49 % (0.16Ω) 49 % (0.17Ω) 49 % (0.17Ω) (d). Case 1, 2, μ r =1() μ r =10(), μ r =10 j0.2, μ r =10j0.6 H-field. H-field H-field 그림 7. Case 1 H-field Fig. 7. Magnitude of H-field in Case % 27.2 % , Q , % [5]. 7, A H-field. Z 그림 9. (r=5.5 cm, d=24 cm, w=1 cm) Fig. 9. WPT system with a conductor material. 308

6 ., (tanδ), H-field., MRI. References 그림 10. Case 3 Fig. 10. Magnitude of H-field in Case 3.. 3,, 27 %, H-field A. 3.. 결론. (R L,opt ). kq F m., Copper F m. EM 1020 % [1] N. Tesla, U.S. patent 1,119,732, [2] A. Kurs et al., "Wireless power transfervia strongly coupled magnetic resonances", Science, vol. 317, pp , Jul [3] Chunlai Yu, Rengui Lu, Yinhua Mao, Litao Ren, and Chunbo Zhu, "Research on the model of magnetic-resonance based wireless energy transfer system", Vehicle Power and Proplsion Conference, pp , Sep [4] I. Awai, T. Komori, "A simple and versatile design method of resonator-coupled wireless power transfer systerm", Proc. ICCCAS2010, Jul [5] Gunyoung Kim, Bomson Lee, "Extraction solution for the coupling coefficient at the magnetically coupled wireless power transmission", Journal of the Korea Institute of Electronic Engineering and Science, vol. 23, no. 9, pp Sep [6] Dongho Jeon, Bomson Lee, "Simplified modeling of ring resonators and split ring resonators using magnetization", Journal of Electromagnetics Engineering and Science, vol. 13, no. 2, pp , Jun [7] Taekkyu Oh, Bomson Lee, "Analysis of wireless power transfer using metamaterial slabs made of ring resonators at MHz", Journal of Electromagnetics Engineering and Science, vol. 13, no. 4, Dec [8],, "μ r =1 slab ",,

2011 8: () 2011 92014 2: () [ 주관심분야 ] Antenna, Metamaterials, Microwave Passive Devices,

7 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 3, Mar : () : () [ 주관심분야 ] Antenna, Metamaterials, Microwave Passive Devices, Filter, Wireless Power Transmisson : ( ) : () : () : : [ 주관심분야 ] Microwave Antenna, Metamaterials, RF Tags, Passive Devices, Wireless Power Transmisson 310

THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE Nov.; 25(11),

THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 2014 Nov.; 25(11), 11281134. http://dx.doi.org/10.5515/kjkiees.2014.25.11.1128 ISSN 1226-3133 (Print)ISSN 2288-226X (Online)