Magnetic Resonant Wireless Power Transfer with Rearranged Configurations

Seok Hyon Kang,Chang Won Jung 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.2

We investigate the indirect-fed magnetic resonant wireless power transfer (MR-WPT) system for wireless charging for mobile devices by rearranging the loops and coils. Conventional MR-WPT is difficult to apply to consumer electronic products because of the arrangement of the resonators. In addition, there are restrictions for charging using a wireless technology, which depend on the circumstances of the usage scenarios. For practical applications, we analyzed the transfer efficiency of the MR-WPT system with various combinations and positions of resonators. Three rearranged configurations (Out-Out, Out-In, In-In) have been considered and experimentally investigated using hollow pipe loops and wire copper coils. There were four types of loops and two types of coils; each one had a different diameter and thickness. The results of the measurements show that the trends of the transfer efficiencies for the three configurations were similar. A transfer efficiency of 82.5% was achieved at a 35-cm distance between the 60-cm diameter transmitter (Tx) and receiver (Rx) coils.

Textile Resonators With Thin Copper Wire for Wearable MR-WPT System

Kang, Seok Hyon,Jung, Chang Won THE INSTITUTE OF ELECTRICAL ENGINEERS 2017 IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS Vol.27 No.1

<P>This letter presents the comparison of performance of planar textile resonators (PTRs) with various forms of conductive patterns. The conductive materials of the conductive pattern included copper sheet and copper wires of three different thicknesses. The PTRs with thin copper wires were found to be flexible and stable for wearable applications. To verify the performance of PTRs in MR-WPT, a symmetrical four-coil system was measured. This study considered the normal and standard condition of PTRs without any forms of modification in physical. The results showed that thin copper wires, especially of 1.0 mm thickness, had the highest transfer efficiency of 75.66% because the thickness of copper sheet is not sufficient for skin depth and the current was over ampacity of copper sheet.</P>

Analysis of MR-WPT using planar textile resonators for wearable applications

Kang, Seok Hyon,Nguyen, Van Thuan,Jung, Chang Won IET 2016 IET microwaves, antennas & propagation Vol.10 No.14

<P>This study presents the design and analysis of a magnetic resonant coupling wireless power transfer (MR-WPT) system that employs planar textile resonators. To reduce the size of the system for wearable applications, the transmitter and receiver are designed and fabricated on a flat plane of fabric. A proposed symmetric four-resonator MR-WPT system is used for verifying the electromagnetic property of the textile substrates. Two textile substrates: polyester and cotton fibre are investigated to determine their impact on the transfer efficiency. Experiments show that the transfer efficiency is considerably higher with the polyester substrate than with the cotton substrate. In addition, copper tape and silver paste are employed for the resonator fabrication because of their flexibility. The measured results show that the copper tape has a significantly higher transfer efficiency than the silver paste because of its high conductivity. At a transfer distance of 5 cm, the maximum transfer efficiency is 50% with the polyester substrate and the copper tape resonator. Furthermore, the width of the coil-pattern is varied to determine its impact on the resonant frequency and the transfer efficiency of the MR-WPT system. This research confirms the feasibility of using flexible MR-WPT for wearable applications.</P>

Transparent Patch Antenna Using Metal Mesh

Kang, Seok Hyon,Jung, Chang Won Institute of Electrical and Electronics Engineers 2018 IEEE Transactions on Antennas and Propagation Vol. No.

<P>This communication presents the design, fabrication, and measurement of transparent antennas with metal mesh (MM) for wireless transparent applications such as smart windows, transparent mobile devices, and transparent Internet of Things. The MM was proposed as a transparent electrode with high conductivity in electrical performance, with proper transparency in optical performance, and low fabrication cost compared to a traditional transparent thin film electrode. To analyze the performance of a transparent antenna fabricated by MM, the antennas were designed to operate in the 2.4–2.5 GHz WLAN band (802.11b). The conductive metal of transparent MM patch antennas was designed using a square lattice structure and was fabricated using wired MM with copper wire (0.2–0.5 mm). In addition, micro-MM film consisting of thin copper wire ( <TEX>$20~\mu \text{m}$</TEX>) was used to fabricate transparent patch antennas. The realized gain, efficiency, front-to-back ratio, and radiation patterns of the transparent MM patch antennas are discussed for various combinations of radiator and ground planes. Overall, the transparent MM patch antennas offer optical transparency, maintain sufficient performance, and could possibly be used in wireless transparent applications.</P>

Magnetic Resonant Three-Coil WPT System Between Off/In-Body for Remote Energy Harvest

Kang, Seok Hyon,Choi, Jung Han,Harackiewicz, Frances J.,Jung, Chang Won THE INSTITUTE OF ELECTRICAL ENGINEERS 2016 IEEE Microwave and Wireless Components Letters Vol. No.

<P>In this letter, the effect of the human body in a magnetic resonance wireless power transfer (MR-WPT) system for wearable and implantable devices is studied. To implement the experiment, muscle-mimicking liquid is configured with parameters similar to those of the human body. The transmitter part is located outside the human body (in the air), and the receiver part is implanted in the liquid. The proposed 3-coil MR-WPT system, which operates at 6.78 MHz shows effectively higher transfer efficiencies compared with a 4-coil MR-WPT system at near transfer distance which is the predicted position for a pacemaker. The results indicate that the proposed system with optimized receiver using air-pocket has potential applications in off/in-body devices that benefit from remote energy harvesting, especially at near distances such as pacemakers.</P>

자기공진형 무선전력전송 시스템의 소형화를 위한 공진기 설계

강석현(Seok Hyon Kang),정창원(Chang Won Jung) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.2

본 논문에서는 소형 모바일 기기에 적용이 가능하도록 코일형 및 루프형 공진기의 평면화를 통해 소형화하여 자기공진형 무선전력전송 시스템을 구축하였다. 제안된 디스크형 이중코일공진기(disk type double coil resonator)는 아크릴 기판(acrylic substrate)의 양면에 얇은 구리 재질을 2 mm의 넓이(width)와 1 mm의 간격(pitch)으로 8번 감은 수의 나선코일패턴을 설계하여 최외각단을 연결한 구조이다. 이 공진기는 구리 재질의 패턴 길이에 의한 유도용량과 각 양쪽 나선코일패턴간의 아크릴 사이에 발생하는 정전용량을 이용하여 6.78 MHz에서 공진한다. 공진기에 설계된 나선코일패턴의 크기는 최외각 지름이 9 cm로 소형화 되었다. 급전 및 부하공진기로 사용되는 루프는 5 mm 굵기의 동선을 이용하여 지름 10cm의 단일 루프로 구현하였다. 또한, 6.78 MHz에서 공진할 수 있도록 3,300 pF 커패시터(capacitor)를 직렬로 연결하였다. 디스크형 이중코일공진기의 특성을 알아보기 위해 다양한 공진기 재배열을 통해 시스템을 구성 및 측정하였으며, 소형무선전력전송 시스템의 최대 전송효율은 35.67 %를 보였다. 제안된 공진기의 구조를 통해 더 작은 소형화 구조 설계가 가능할 것으로 기대된다. In this paper, we miniaturized the loop and coil in magnetic resonance wireless power transfer(MR-WPT) system for application to the small mobile device. The proposed disk type double coil resonator was designed to cause resonance at 6.87 MHz. It is composed of thin copper on both-side of acrylic substrate structured 2 mm width, 1 mm pitch and 8 turns. The outer radius of spiral coil pattern is 9 cm. And the proposed loop was made of the copper wire 5 mm diameter of cross-section. The size of loop is 10 cm diameter. For resonance at 6.87 MHz, the capacitor with 3,300 pF was connected in series on the loop. We rearranged the resonators and organized several WPT systems which is rearranged by resonators. The highest transfer efficiency of miniaturized WPT system was 35.67 %. This proposed design of spiral double coil will contribute to make resonator smaller for appling small and thin mobile device.

정방형 메탈메쉬 투명전극을 이용한 투명 사각 패치 안테나

강석현(Seok Hyon Kang),정창원(Chang Won Jung) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.4

본 논문은 향후 투명 디스플레이, 스마트글래스(smart glass) 등의 그 활용도가 증가 추세에 있는 투명전극과 관련된 논문이며, 본 논문에서는 투명 안테나 등의 투명 고주파 수동소자 설계 시, 투명 디스플레이 등에 가장 많이 사용되고 있는 ITO(Indium-Tin-Oxide)을 이용한 박막형(thin film type) 투명전극의 낮은 전기적 특성(면저항e>5 (Ω/sq))으로 인한 성능저하를 개선하고자, 고주파 소자에 가장 일반적으로 사용되는 도체인 구리선(copper wire)으로 구현되는 정방형 메탈메쉬(square metal mesh)를 이용하여 투명전극을 구현하고, 이를 기본 단위로 하여 투명 패치 안테나를 구현하였고, 그 성능을 비교 분석하였다. 본 논문에서는 투명전극의 기본 설계 블록인 정방형 메탈메쉬의 광학적 특성(광 투과도) 및 전기적 특성(면저항)을 측정 및 분석하였고, 이를 이용하여 투명 패치 안테나를 설계, 측정, 분석하였다. 또한, 정방형 메탈메쉬는 광 투과도를 높이기 위해 얇은 구리선(w=0.2 ㎜)을 사용하였으며, 망(mesh) 크기(l=1, 2 ㎜)에 따른 광 투과도와 안테나 성능(방사이득, 방사패턴)과의 관계를 분석하였다. 투명 안테나 성능 측정 결과, 안테나 성능은 정방형 메탈메쉬의 광학적 특성과 반비례하며, 실제 활용 시에는 광학적 특성, 전기적 특성, 제작비용을 종합적으로 고려하여, 응용에 따른 투명 안테나의 활용이 필요하다. This paper reports the transparent electrode, which would be applied to transparent displays and smart glasses. Herein, a squared metal mesh with the most widely used copper wire in microwaves is studied for the alternating thin-film-type transparent and conducting indium tin oxide(ITO), with a low conductivity(sheet resistance > 5 Ω/sq.). The electromagnetic performance of a patch antenna with metal mesh is analyzed. This paper presents the results of the optical(OT, optical transparent) and electrical(sheet resistance) characteristics of a squared metal mesh, which is a basic design. To improve the OT, copper wire(w=0.2 ㎜) is used in fabricating the squared metal mesh and the relationship between the OT and the antenna performance(radiation gain, radiation pattern) was analyzed according to the mesh size(l=1, 2 ㎜). The measurement results show that the antenna performance and the optical characteristic are in inverse proportion to each other. In real applications, the optical and electrical characteristics, and the costs of production are to be considered.

모바일 디바이스를 위한 재배열 간접급전 무선전력전송 시스템

강석현(Seok Hyon Kang),응웬반투안(Van Thuan Nguyen),정창원(Chang Won Jung) 한국산학기술학회 2015 한국산학기술학회 학술대회 Vol.2015 No.1

본 논문에서는 다양한 전자제품에 어플리케이션 할 수 있도록 간접급전식 공진형 무선전력전송 시스템을 구성하는 공진기의 재배열을 제시하고 이에 대해 분석하였다. 재배열 무선전력전송 시스템은 루프를 기준으로 공진기의 배열에 따라 Out-out, Out-in, In-in 으로 분류하였으며, 실용적인 어플리케이션을 위해 Out-in 을 변형한 L형 무선전력전송 시스템을 추가하였다. 전송효율을 측정한 결과, 세 가지 시스템은 공진주파수가 안정된 전송거리 50 cm 이상에서 비슷한 결과를 보였으며, 오히려 기본배열(Out-out)보다 재배열(Out-in, In-in)이 평균 약 3.8% 높았다. Out-in 의 기본형과 L형의 비교 분석에서는 기본형이 L형보다 평균 약 27.7% 높았으나, L형이 최고효율 64.5 %를 보였으며, 부하공진기의 형태가 변형되어도 전송효율에 큰 영향을 미치지 않았다. 이를 통해 무선전력전송 시스템의 어플리케이션은 공진기의 재배열을 통해 해결이 가능하다는 것을 보여주었다.

의복용 자기공진형 무선전력전송 시스템을 위한 평면형 직물공진기의 설계 및 연구

강석현(Seok Hyon Kang),정창원(Chang Won Jung) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.8

본 논문에서는 의복용 무선전력전송 시스템을 구축을 위한 평면형 직물공진기를 제안하고, 공진기에 사용된 의복용 직물기판의 재질별 특성을 분석하였다. 평면형 직물공진기는 공진주파수가 1-10 ㎒가 되도록 직물기판 위에 전도성 물질로 루프 및 코일을 평면 설계하였다. 의복용으로 많이 사용되고 있는 폴리에스테르 섬유와 면을 직물기판으로 사용하였으며, 평면 루프와 코일은 동테이프(copper tape)와 실버페이스트(silver paste)로 설계하였다. 자기공진형 무선전력전송 시스템에 적용된 직물의 재질별 특성을 분석하기 위해 송신부와 수신부를 대칭으로 설계하였다. 실험 결과, 낮은 유전상수 및 비교적 두꺼운 두께를 가진 직물기판과 표면저항이 작은 도체성 재질의 패턴(루프 및 코일)으로 제작되었을 때, 의복용 무선전력전송 시스템이 높은 전송효율을 보였다. 본 연구를 통해 제안된 평면형 직물 공진기는 무선전력전송 기술의 영역을 의복용으로 넓힐 수 있는 가능성을 보여주었다. In this paper, we proposed the planar textile resonator for constructing wearable MR-WPT system and analyzed the characteristic of textile substrates used in resonators. The planar textile resonators were designed to resonate at 1-10 ㎒. The loop and coil were fabricated planar structure on textile substrate using conductive materials. Polyester fiber and cotton widely used in real life were chosen as textile resonators for wearable applications and copper tape and silver paste were used for fabricating planar loop and coil on textile substrate. For comparison analysis on transfer efficiency according to the types of textile, transmitter and receiver parts were symmetric. According to the result, for the highest transfer efficiency of wearable WPT system, the planar resonators have specifications of relative thick textile substrate with low permittivity and low surface resistance of conductive pattern. The performed experiments show that the planar textile resonator is possible to be used for resonator in wearable MR-WPT system.

인체 내 무선전력전송을 위한 인체이식용 공진기의 최적화 설계 및 분석

강석현(Seok Hyon Kang),정창원(Chang Won Jung) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6