• Title/Summary/Keyword: Wireless Power Transfer(WPT)

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Design of a High Power Frequency Tuneable Resonator for Wireless Power Transfer (무선 전력 전송용 고출력 주파수 가변 공진기 설계)

  • Park, Jaesu;Choi, Jaehoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.3
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    • pp.352-355
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    • 2013
  • In this paper, a high power tuneable resonator for a wireless power transfer system based on magnetic resonance is proposed. A spiral structure is used for a self-resonant coil and tuneable trimmer capacitors are added at the edges of resonant coils such that the frequency can be easily tuned. 3D simulation tools and equivalent circuit modeling method are used for predicting self-resonant frequency and scattering parameters according to the change of capacitor values. From the measurement of the prototype WPT system, the resonant frequency could be controlled from 3.0 MHz to 4.5 MHz and the transmission efficiency way over 50 % when the distance between transmitting coil and receiving coil was 160 mm.

Magnetic Resonant Wireless Power Transfer Using Reconfigurable Slit Ground Resonator for Laptop Computer (재구성 슬릿 그라운드 공진기를 이용한 노트북용 자기공진형 무선전력전송)

  • Kang, Seok Hyon;Jung, Chang Won
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.1
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    • pp.69-75
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    • 2017
  • In this paper, slit ground resonator with slit and capacitor is proposed for practical use of magnetic resonant wireless power transfer(MR-WPT). And this paper presents the performance comparison of conventional loop resonator as Rx resonator to slit ground resonator. The proposed silt ground resonator with 31 cm width, 20.5 cm length, $35{\mu}m$ thickness is designed the crossing slit 1 cm width with only opened edge. And an external capacitors were connected at the opened edge of slit ground resonator for resonating at 6.78 MHz. The transfer efficiencies of MR-WPT were measured at open and short mode, and then the highest transfer efficiencies of MR-WPT according to the Rx resonators were plotted. In result, the transfer efficiency of MR-WPT with loop resonator was the highest. However, when the ground was inserted in receiver part at the bottom of laptop model, the transfer efficiency was closed 0 %. The transfer efficiency recovered the transfer efficiency of 67 % using slit ground resonator. The magnetic field was penetrated through the slit and proposed slit ground resonator works as resonator in MR-WPT.

Implementation of Wireless Power Transfer Circuit by Using Magnetic Resonant Coupling Method

  • Lho, Young-Hwan
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.306-309
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    • 2019
  • Wireless charging is a technology of transmitting power through an air gap to an electrical load for the purpose of energy dissemination. Compared to traditional charging with code, wireless power charging has many benefits of avoiding the hassle from connecting cables, rendering the design and fabrication of much smaller devices without the attachment of batteries, providing flexibility for devices, and enhancing energy efficiency, etc. A transmitting coil and a receiving coil for inductive coupling or magnetic resonant coupling methods are available for the near field techniques, but are not for the far field one. In this paper, the wireless power transfer (WPT) circuit by using magnetic resonant coupling method with a resonant frequency of 13.45 Mhz for the low power system is implemented to measure the power transmission efficiency in terms of mutual distance and omnidirectional angles of receiver.

Pickup system design for wireless power transfer (무선전력전송을 위한 집전 시스템 설계)

  • Lee, Dong-Su;Lim, Dong-Nam;Jeon, Seong-Jeub
    • Proceedings of the KIPE Conference
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    • 2012.07a
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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.

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Design Guidelines for a Capacitive Wireless Power Transfer System with Input/Output Matching Transformers

  • Choi, Sung-Jin
    • Journal of Electrical Engineering and Technology
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    • v.11 no.6
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    • pp.1656-1663
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    • 2016
  • A capacitive wireless power transfer (C-WPT) system uses an electric field to transmit power through a physical isolation barrier which forms a pair of ac link capacitors between the metal plates. However, the physical dimension and low dielectric constant of the interface medium severely limit the effective link capacitance to a level comparable to the main switch output capacitance of the transmitting circuit, which thus narrows the soft-switching range in the light load condition. Moreover, by fundamental limit analysis, it can be proved that such a low link capacitance increases operating frequency and capacitor voltage stress in the full load condition. In order to handle these problems, this paper investigates optimal design of double matching transformer networks for C-WPT. Using mathematical analysis with fundamental harmonic approximation, a design guideline is presented to avoid unnecessarily high frequency operation, to suppress the voltage stress on the link capacitors, and to achieve wide ZVS range even with low link capacitance. Simulation and hardware implementation are performed on a 5-W prototype system equipped with a 256-pF link capacitance and a 200-pF switch output capacitance. Results show that the proposed scheme ensures zero-voltage-switching from full load to 10% load, and the switching frequency and the link capacitor voltage stress are kept below 250 kHz and 452 V, respectively, in the full load condition.

Realization of Optimum Loads for Maximum WPT Efficiencies Using Multi-Turn Receiving Coil (수신 코일 권선 수 변화에 의한 무선전력전송 최적 부하 구현)

  • Hwang, Sungyoun;Lee, Bomson
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.4
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    • pp.335-341
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    • 2016
  • In this paper, we propose the method of controling the turns of a receiving coil for the matching directly to the receiver input impedance(typically $50{\Omega}$) with a maximum wireless power transfer(WPT) efficiency. Based on the presented the expression of the optimum load depending on a system figure of merit, number of the turns of a receiving coil, and proximity effect between conducting lines, the theoretical efficiencies have been compared with the measured ones with a good agreement. The results of this work may be used to realize a allowable maximum efficiency with a simple and low-profile 2-coil WPT system not requiring a separate feeding loop.

Analysis of transmission efficiency of the superconducting resonance coil according the materials of cooling system

  • Lee, Yu-Kyeong;Hwang, Jun-Won;Choi, Hyo-Sang
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.1
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    • pp.46-49
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    • 2016
  • The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

A Study on Transmission Efficiency of Wireless Power Induction and Resonant Charging Methodologies (무선 유도 및 공진 충전방식의 전송효율 연구)

  • Lho, Young Hwan
    • Journal of IKEEE
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    • v.23 no.2
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    • pp.747-750
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    • 2019
  • Wearable devices have become practically indispensable to daily life and helped people track and manage fitness, health, and medical functions etc. As these wearable devices become smaller and more comfortable for the user, the demand for longer run time and charging ways presents new challenges for the power management engineer. Wireless power transfer (WPT) is the technology that forces the power to transmit electromagnetic field to an electrical load through an air gap without interconnecting wires. This technology is widely used for the applications from low power smart phone to high power electric railroad and main electrical grid. There are two kinds of WPT methods: Inductive coupling and magnetic resonant coupling. The model using magnetic resonant coupling method is designed for a resonant frequency of 13.45 MHz. In this study, the hardware implementations of these two coupling methods are carried out, and the efficiencies are compared.

Analysis of Wireless Power Transfer Using Metamaterial Slabs Made of Ring Resonators at 13.56MHz

  • Oh, TaekKyu;Lee, Bomson
    • Journal of electromagnetic engineering and science
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    • v.13 no.4
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    • pp.259-262
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    • 2013
  • This paper analyzes the effects of metamaterial slabs with negative permeability when applied to a two-loop wireless power transmission (WPT) system, both in theory and electromagnetic (EM) simulations. The analysis of magnetic flux focusing provided here assumes quasi-magnetostatics or magnetostatics. The slab structures with negative permeability have been realized using the periodically arrayed ring resonators (RRs) at 13.36MHz. Some examples with ideal lossless slabs of -1, -2, and -3 showed a great enhancement of WPT efficiencies when compared with the free space cases. However, practical lossy slabs made of planar copper RRs did not show significant enhancement of WPT efficiencies due to the relatively high losses in the ring resonator (or in the slab consisting of RRs) near the resonant frequency.

Electric Field Effect on Numerical Dosimetry for Wireless Power Transfer System (무선전력전송의 조사량 평가 시 전기장 영향)

  • Park, Sang-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.5
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    • pp.499-505
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    • 2015
  • The coupling effect of electric fields incident on the biological object is investigated in regards to dosimetry for a wireless power transfer(WPT) system using electromagnetic resonance phenomenon. The internal electric fields induced a biological sphere model exposed to a magnetic dipole are calculated with the finite-difference time-domain(FDTD) method considering both incident electric and magnetic fields, the impedance method considering only incident magnetic fields, and theoretical analysis. The results represent that the electric coupling effect on a biological object nearby the WPT system should be considered to conduct exact dosimetry.