• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.49-50
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• 2017

In a two-dimensional wireless power transfer system, the mutual inductance angle is the most important parameter for determining the power transmission efficiency. This paper presents a technique to estimate the mutual inductance angle from the voltage and current information of the transmitting (Tx) coils. The equation to estimate the mutual inductance angle is derived, and the validity of the proposed method is verified through simulation and experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.381-382
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• 2012

Wireless power transfer (WPT) system studied recently is very attractive because it removes power cables from home appliances, office equipment and battery chargers for electric vehicle. In this paper a pickup design method based on a conventional design method is proposed. A prototype pickup system designed according to the proposed method is constructed and tested, and its validness is verified.

• 한국컴퓨터정보학회논문지
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• 제28권9호
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• pp.121-128
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• 2023

무선 센서 네트워크에서 네트워크의 수명을 증가시키기 위해 주변 환경으로부터 에너지를 수집하거나, 무선 전력 전송으로 직접 에너지를 전달하는 방법이 사용되고 있다. 또한 에너지의 불균형을 줄이고 데이터의 수집량을 증가시키기 위해 직접 센서 노드를 방문해서 자료를 수집하는 모바일 싱크 노드를 활용한 방법이 사용되고 있다. 본 논문에서는 이러한 환경에서 각 센서 노드가 네트워크 환경과 에너지를 고려하여 Minimum Depth Tree (MDT)를 구성하고 자식 노드에 자료수집량을 할당해줌으로써 중계 노드의 부하를 줄이고 전체적으로 많은 데이터를 고르게 수집하는 기법을 제안한다. 시뮬레이션 결과, 본 기법은 기존의 다른 기법에 비해 에너지 고갈을 효과적으로 억제하고 더 많은 자료를 수집하는 것을 보여준다.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1206-1218
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• 2016

This article proposes a highly reliable power and communication system that guarantees the protection of essential instruments in a nuclear power plant under a severe accident. Both power and communication lines are established with not only conventional wired channels, but also the proposed wireless channels for emergency reserve. An inductive power transfer system is selected due to its robust power transfer characteristics under high temperature, high pressure, and highly humid environments with a large amount of scattered debris after a severe accident. A thermal insulation box and a glass-fiber reinforced plastic box are proposed to protect the essential instruments, including vulnerable electronic circuits, from extremely high temperatures of up to $627^{\circ}C$ and pressure of up to 5 bar. The proposed wireless power and communication system is experimentally verified by an inductive power transfer system prototype having a dipole coil structure and prototype Zigbee modules over a 7-m distance, where both the thermal insulation box and the glass-fiber reinforced plastic box are fabricated and tested using a high-temperature chamber. Moreover, an experiment on the effects of a high radiation environment on various electronic devices is conducted based on the radiation test having a maximum accumulated dose of 27 Mrad.

• ETRI Journal
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• 제43권3호
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• pp.389-399
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• 2021

In this paper, we propose one-bit feedback-based distributed beamforming (DBF) techniques for simultaneous wireless information and power transfer in interference channels where the information transfer and power transfer networks coexist in the same frequency spectrum band. In a power transfer network, multiple distributed energy transmission nodes transmit their energy signals to a single energy receiving node capable of harvesting wireless radio frequency energy. Here, by considering the Internet-of-Things sensor network, the energy harvesting/information decoding receivers (ERx/IRx) can report their status (which may include the received signal strength, interference, and channel state information) through one-bit feedback channels. To maximize the amount of energy transferred to the ERx and simultaneously minimize the interference to the IRx, we developed a DBF technique based on one-bit feedback from the ERx/IRx without sharing the information among distributed transmit nodes. Finally, the proposed DBF algorithm in the interference channel is verified through the simulations and also implemented in real time by using GNU radio and universal software radio peripheral.

• 한국전자파학회논문지
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• 제21권1호
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• pp.36-45
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• 2010

본 논문에서는 가전기기 등에 무선으로 전력을 전송하는 것을 목표로 루프 안테나를 이용한 무선 전력 전송 시스템의 새로운 설계 방법을 제안하였다. 본 설계 방법은 복잡한 전자기 시뮬레이션 없이 간단한 결합 계수의 측정과 루프 안테나의 등가 회로 모델에 대한 근사식만으로 무선 전력 전송 시스템을 설계할 수 있다. 본 논문에서 제시한 설계 방법에 따라 13.56 MHz에서 동작하는 $50{\times}50\;cm^2$ 크기를 갖는 루프 안테나 쌍을 설계하고, 거리에 따른 입력 반사 계수, 결합 계수, 효율 및 임피던스 변화를 측정하였다. 측정 결과, 본 논문에서 제안한 설계 방법이 입력 임피던스 특성을 정확하게 예측할 수 있음을 확인하였다. 또한 50 cm 이하의 거리에서 본 논문의 설계 방법을 이용하여 임피던스 정합한 무선 전력 전송 시스템이 일반적인 $50\;{\Omega}$ 임피던스 정합 회로를 갖도록 설계된 경우보다 효율이 2배 정도 개선되는 것을 확인하여 제안한 설계법의 유용성을 확인하였다.

• Journal of Communications and Networks
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• 제18권6호
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• pp.926-937
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• 2016

In this paper, we study the feasibility of receiver diversity for application to downlink cellular networks, where low-energy devices are equipped with information decoding and energy harvesting receivers for simultaneous wireless information and power transfer. We compare several options that are based on selection combining and maximum ratio combining, which provide different implementation complexities. By capitalizing on the Frechet inequality, we shed light on the advantages and limitations of each scheme as a function of the transmission rate and harvested power that need to be fulfilled at the low-energy devices. Our analysis shows that no scheme outperforms the others for every system setup. It suggests, on the other hand, that the low-energy devices need to operate in an adaptive fashion, by choosing the receiver diversity scheme as a function of the imposed requirements. With the aid of stochastic geometry, we introduce mathematical frameworks for system-level analysis. We show that they constitute an important tool for system-level optimization and, in particular, for identifying the diversity scheme that optimizes wireless information and power transmission as a function of a sensible set of parameters. Monte Carlo simulations are used to validate our findings and to illustrate the trade-off that emerge in cellular networks with simultaneous wireless information and power transfer.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.113-116
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• 2015

본고에서는 블루투스 프로토콜을 이용해서 무선전력전송을 제어하는 시스템에 대해서 기술하였다. 블루투스는 근거리에서 데이터, 음성 신호 등 송수신하기 위해 많은 분야에서 다양하게 응용되어 왔다. 그러나 최근에는 전송 데이터량이 적은 센서 제어 신호를 저전력으로 처리할 수 있는 기존 블루투스 프로토콜보다 단순한 구조의 블루투스 저에너지 프로토콜이 표준화되어 의료, 가전 등 생활과 밀착된 응용에 많이 사용되고 있다. 또한 무선전력 전송시스템에서도 제어를 위해 표준으로 채택되었다. 본고에서는 특히 블루투스 저에너지 프로토콜을 이용해서 무선전력전송시스템을 제어하는 기술에 대해서 분석하고 기술하였다.

• 한국컴퓨터정보학회논문지
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• 제23권11호
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• pp.193-201
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• 2018

In this paper, we extracted relevant patent data and conducted statistical analysis to understand the technical development trend related to Wireless Power Transfer (WPT) for Light Rail Transit (LRT). Recently, with the development of WPT technologies, the Light Rail Transit (LRT) industry is concentrating on applying WPT to the power supply system of trains because of their advantages compared wired counterpart, such as low maintenance cost and high stability. This technology is divided into three areas: wireless feeding and collecting technology, high-frequency power converter technology and orbital and infrastructure technology. From each specific area, key words in patent document were extracted by TF-IDF method and analyzed by social network. In the keyword network, core word of each specific technology were extracted according to their degree centrality. Then, the multi-word phrases were also built to represent the concept of core technologies. Finally, based on the analysis results, the development strategies for each specifics technical area of WPT in LRT filed will be provided.

• 전력전자학회논문지
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• 제24권4호
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• pp.303-309
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• 2019

A hybrid control of a rectifier/regulator of wireless power transfer systems for electric vehicles is studied. A combined rectifier/regulator is used for charging control. The hybrid control comprises integral cycle control and pulse width modulation control to cope with the variations in the induced voltage due to clearance and alignment. The hybrid control has good control capability and does not cause severe switching loss. A 22 kW prototype of the Wireless Power Transfer class 4 charging system defined by the Society of Automotive Engineers is constructed and tested to verify the proposal.