• Title/Summary/Keyword: Wireless Power Transmission

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Study on Discharge Phenomenon Occurring in Transmitting Resonance Coil of Wireless Power Transmission (무선전력전송의 송전 공진코일에서 발생하는 방전현상 연구)

  • Gi-Bum Lee
    • The Journal of the Korea institute of electronic communication sciences
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    • v.19 no.2
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    • pp.355-360
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    • 2024
  • In this paper, in implementing a 4-coil resonant wireless power transmission system, we studied the discharge phenomenon that occurs at the end of the transmitting resonance coil. Resonant wireless power transmission consists of a power supply coil, a transmitting resonance coil, a power receiving resonance coil, and a load coil. The transmitting resonance coil serves to amplify the magnetic field generated from the power supply coil and transmits it to the front receiving resonance coil. When a high current flows through the power supply coil in order to transmit large power, a high voltage is induced at the end of the transmitting resonance coil. It causes line-to-line discharge. Line-to-line discharge phenomenon damages the transmitter case and renders the transmitter unusable. Therefore, in order to eliminate this line-to-line discharge phenomenon, the voltage induced in the transmitting resonance coil that causes line-to-line discharge was analyzed and a solution was proposed.

A Transmit Power Control Method for Low-Power Communication in 802.11b Infrastructure Networks (IEEE 802.11b Infrastructure 환경에서 저전력 통신을 위한 전송 전력 제어 기법)

  • Kwon Do Han;Jung Hee Lock;Park Chang Yun;Jung Chung ll
    • Journal of KIISE:Information Networking
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    • v.32 no.2
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    • pp.180-189
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    • 2005
  • This paper describes a transmission power control method for power saving in 802.11b wireless LANs. We have first explored how much effects reducing transmission power has on communication performance. Then we propose a power control algorithm, whose approach is similar to that of TCP congestion control, determining an appropriate transmission power level by monitoring the retransmission rate. We have implemented an utility software on a Linux-based system and made several experiments to validate the proposed method. The results show that it is possible to save energy consumption by controlling transmission power without sacrificing communication performance.

Analysis of Magnetically Coupled Wireless Power Transmission for Maximum Efficiency

  • Kim, Chung-Ju;Lee, Bom-Son
    • Journal of electromagnetic engineering and science
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    • v.11 no.3
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    • pp.156-160
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    • 2011
  • We have proposed and analyzed an equivalent circuit for a magnetically coupled wireless power transmission (WPT) system between two loop resonators by considering its coupling coefficient and radiation-related parameters. A complete formulation is provided for all the necessary circuit parameters. The mechanism of radiation loss is sufficiently explained. The circuit and electromagnetic (EM) simulation results have been shown to be in good agreement. Based on the proposed circuit formulation, a specific load impedance for maximum WPT efficiency was found to exist. The proposed modeling of the WPT in terms of circuit characterizations provides sufficient insight into the problems associated with WPT.

Wireless Power Transmission between Two Metamaterial-Inspired Loops at 300 MHz

  • Kim, Gun-Young;Jung, Youn-Kwon;Lee, Bom-Son
    • Journal of electromagnetic engineering and science
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    • v.10 no.4
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    • pp.219-223
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    • 2010
  • Based on a provided closed-form wireless power transmission (WPT) efficiency formula, which may be used for any value of load, we have analyzed the WPT efficiencies between two metamaterial-inspired loop antennas in various aspects. Due to the modeling based on low frequency circuit theory, the provided formula at the center resonant frequency has been found to be accurate until when the distance between the two loop antennas increases to 15 cm (about $\lambda_0/6$ at 300 MHz). When the two loops get closer, the resonant frequency has been found to split into two in theory, simulations, and measurements. The EM-simulated and measured efficiencies at new resonant frequencies are 60.9 % and 46.3 %, respectively, at d=15 cm. With two extra rings around the loops, the maximum efficiency is enhanced to 93.7 % at d=15 cm. The effect of the additional two rings is about 30 %.

RF-DC Voltage Multiplier Design and Fabrication for 5.8GHz Microwave Wireless Power Transmission (5.8GHz 마이크로파 무선전력전송을 위한 RF-DC 전압 체배기 설계 및 구현)

  • Lee, Seong Hun;Son, Myung Sik
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.2
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    • pp.85-88
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    • 2017
  • In this paper, we have designed and fabricated a RF-DC voltage multiplier for 5.8GHz microwave wireless power transmission. In order to obtain higher voltage, the RF-DC voltage multiplier with 10 diodes (D-10) and the receiver module with an antenna and BPF (Band Pass Filter) was manufactured. The measured and compared results show that the voltages of the proposed one are lower than those of the previous tripler module up to 40cm. However, the voltage of the proposed one with the voltage multiplier is higher than that of the tripler module at the distances of 45cm and 50cm due to the voltage multiplier with 10 diodes.

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A Tree-based Greedy Algorithm for Minimum Power Broadcast in Wireless Networks (무선 네트워크에서 최소 전력 브로드캐스트를 위한 트리 기반 탐욕 알고리즘)

  • Lee, Dong-ho;Jang, Kil-woong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.5
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    • pp.921-928
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    • 2017
  • Unlike wired networks, broadcasting in wireless networks can transmit data to several nodes at a time in a single transmission. The omnidirectional broadcasting of node in wireless networks simultaneously reaches all neighboring nodes. In this paper, we propose a greedy algorithm to solve the minimum power broadcasting problem that minimizes the total transmission power when broadcasting in wireless networks. The proposed algorithm uses a neighborhood list which is a set of nodes that can transmit messages within the maximum transmission range of each node, and among the transmitting nodes that have received the data, the node having the largest number of the neighboring nodes firstly transmits the data to neighboring node. The performance of the proposed algorithm was evaluated by computer simulation, and was compared with existing algorithms in terms of total transmission power and broadcasting frequency for broadcasting to all nodes. Experiment results show that the proposed algorithm outperforms the conventional algorithms.

Analysis of Shielding Characteristics for Induction Phenomenon Attenuation of Large Capacity Wireless Power Transmission Environment (대용량 무선전력전송 환경 유도현상 감쇄를 위한 차폐 특성 분석)

  • Chae, Dong-Ju;Kim, Young-Seok;Jung, Jin-Soo;Lim, Hyun-Sung;Cho, Sung-Koo;Hong, Seong-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.12
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    • pp.1844-1851
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    • 2017
  • As the capacity of the wireless power transmission increases, a higher supply current which may induce current in nearby conductive parts requires. Induced current may affect electric shock to the human body and malfunction of the electrical equipment. In order to prevent such induced phenomena as a risk factor, shielding is required between the source of the wireless power transmission and the conductive parts. The resonance frequency for the large capacity wireless power transmission has the wavelength of several hundred meters, so most environments are included in the near-field area. By wave impedance, the electric field has higher density in the near-field area and needs to be analyze for protecting. For this purpose, it is necessary to select a substance having a larger electric conductivity and optimized shielding structure. In this paper, an aluminum base shielding structure was presented to conduct experiments on thickness, position, and heat dissipation. In the 35 kW, 60 kHz environments, the optimized 5T Al base shielding structure attenuates the induced current to 43 %.

Numerical Method for Exposure Assessment of Wireless Power Transmission under Low-Frequency Band

  • Kim, Minhyuk;Park, SangWook;Jung, Hyun-Kyo
    • Journal of Magnetics
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    • v.21 no.3
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    • pp.442-449
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    • 2016
  • In this paper, an effective numerical analysis method is proposed for calculating dosimetry of the wireless power transfer system operating low-frequency ranges. The finite-difference time-domain (FDTD) method is widely used to analyze bio-electromagnetic field problems, which require high resolution, such as a heterogeneous whole-body voxel human model. However, applying the standard method in the low-frequency band incurs an inordinate number of time steps. We overcome this problem by proposing a modified finite-difference time-domain method which utilizes a quasi-static approximation with the surface equivalence theorem. The analysis results of the simple model by using proposed method are in good agreement with those from a commercial electromagnetic simulator. A simulation of the induced electric fields in a human head voxel model exposed to a wireless power transmission system provides a realistic example of an application of the proposed method. The simulation results of the realistic human model with the proposed method are verified by comparing it with the conventional FDTD method.

Low-Power Wireless Transmission at 2.45 GHz Band (2.45 GHz 대역 소전력 무선 전송)

  • Choi, Ki-Ju;Hwang, Hee-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.8
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    • pp.777-783
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    • 2009
  • In this paper, we implemented a wireless power transmission system at 2.45 GHz. The transmission power is limited within 20 dBm according to the ISM frequency regulations. We used two zero-bias Schottky diode and optimized the RF-DC converter for working a clock at 80 cm distance using a receiver with a single antenna and an Rf-DC converter to reduce parts and cost compared to previously reported literatures.

Analysis of Magnetically Coupled Wireless Power Transmission Efficiency according to Material (주변 물질에 따른 자계결합 무선 전력 전송 시스템의 전송 효율 변화 연구)

  • Oh, TaekKyu;Lee, Bomson
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.3
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    • pp.304-310
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    • 2014
  • 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 11~60 % using the proposed methods by analyzing and comparing the results based on EM simulations.