• Title/Summary/Keyword: wireless power transfer

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Wireless Power Transfer System using Semi-random Magnetic Field (semi-random 자장을 사용하는 적합한 무선전력전송 시스템)

  • Lim, Dong-Nam;Lee, Dong-Su;Jeon, Seong-Jeub
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.480-481
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    • 2014
  • In this paper, a feeder system for wireless power transfer is investigated, which generates semi-random magnetic field using three currents with different frequencies. A semi-random field is very useful to magnetizing a pickup irrespective of its posture.

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Design of DC-DC Converter to Charge and Discharge Ultra-Capacitor Modules for Wireless Trains (무가선 전동차용 울트라커패시터 모듈 충·방전을 위한 DC-DC 컨버터 설계)

  • Jo, Jeong-Min;Han, Young-Jae;Kim, Jae-Won;Lee, Jang-Moo;Kim, Gil-Dong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.12
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    • pp.1776-1781
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    • 2015
  • Electric power trains receive electric power from overhead cables via a pantograph system. Power collector system in trains increase the cross section of tunnel and require a massive coreless filter reactor in propulsion inverter because of the power disturbance by contact loss phenomenon of a train. In this paper we proposed a wireless train which can run to next station with charging energy of ultra-capacitor module block. We designed DC-DC converter to charge and discharge ultra-capacitor modules by using Next Train running test results and confirm the feasibility of the proposed system through simulation.

HF-Band Wireless Power Transfer System with Adaptive Frequency Control Circuit for Efficiency Enhancement in a Short Range (근거리에서 효율 향상을 위해 적응 주파수 제어 회로를 갖는 HF-대역 무선 전력 전송 시스템)

  • Jang, Byung-Jun;Won, Do-Hyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.11
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    • pp.1047-1053
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    • 2011
  • In this paper, we proposed an HF-band wireless power transfer system with adaptive frequency control circuit for efficiency enhancement in a short range. In general, a wireless power transfer system shows an impedance mismatching due to a reflected impedance, because a coupling coefficient is varied with respect to separation distance between two resonating loop antennas. The proposed method can compensate this impedance mismatching by varying input frequency of a voltage-controlled oscillator adaptively with respect to separation distance. Therefore, transmission efficiency is enhanced in a short distance, where large impedance mismatch occurs. The adaptive frequency circuit consists of a directional coupler, a detector, and a loop filter. In order to demonstrate the performance of the proposed system, a wireless power transfer system with adaptive frequency control circuits is designed and implemented, which has a pair of loop antennas with a dimension of 30${\times}$30 $cm^2$. From measured results, the proposed system shows enhanced efficiency performance than the case without adaptive frequency control.

A Frequency-Tracking Method Based on a SOGI-PLL for Wireless Power Transfer Systems to Assure Operation in the Resonant State

  • Tan, Ping-an;He, Haibing;Gao, Xieping
    • Journal of Power Electronics
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    • v.16 no.3
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    • pp.1056-1066
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    • 2016
  • Wireless power transfer (WPT) technology is now recognized as an efficient means of transferring power without physical contact. However, frequency detuning will greatly reduce the transmission power and efficiency of a WPT system. To overcome the difficulties associated with the traditional frequency-tracking methods, this paper proposes a Direct Phase Control (DPC) approach, based on the Second-Order Generalized Integrator Phase-Locked Loop (SOGI-PLL), to provide accurate frequency-tracking for WPT systems. The DPC determines the phase difference between the output voltage and current of the inverter in WPT systems, and the SOGI-PLL provides the phase of the resonant current for dynamically adjusting the output voltage frequency of the inverter. Further, the stability of this control method is analyzed using the linear system theory. The performance of the proposed frequency-tracking method is investigated under various operating conditions. Simulation and experimental results convincingly demonstrate that the proposed technique will track the quasi-resonant frequency automatically, and that the ZVS operation can be achieved.

Three-coil Magnetically Coupled Resonant Wireless Power Transfer System with Adjustable-position Intermediate Coil for Stable Transmission Characteristics

  • Chen, Xuling;Chen, Lu;Ye, Weiwei;Zhang, Weipeng
    • Journal of Power Electronics
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    • v.19 no.1
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    • pp.211-219
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    • 2019
  • In magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the introduction of additional intermediate coils is an effective means of improving transmission characteristics, including output power and transmission efficiency, when the transmission distance is increased. However, the position of intermediate coils in practice influences system performance significantly. In this research, a three-coil MCR WPT system is adopted as an exemplification for determining how the spatial position of coils affects transmission characteristics. With use of the fundamental harmonic analysis method, an equivalent circuit model of the system is built to reveal the relationship between the output power, the transmission efficiency, and the spatial scales, including the axial, lateral, and angular misalignments of the intermediate and receiving coils. Three cases of transmission characteristics versus different spatial scales are evaluated. Results indicate that the system can achieve relatively stable transmission characteristics with deliberate adjustments in the position of the intermediate and receiving coils. A prototype of the three-coil MCR WPT system is built and analyzed, and the experimental results are consistent with those of the theoretical analysis.

DQ Synchronous Reference Frame Model of a Series-Parallel Tuned Inductive Power Transfer System (직렬-병렬 공진 무선전력전송 시스템의 동기 좌표계 모델)

  • Noh, Eun-Chong;Lee, Sang-Min;Lee, Seung-Hwan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.6
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    • pp.477-483
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    • 2020
  • This study proposes a DQ synchronous reference frame model of a series-parallel tuned inductive power transfer (SP-IPT) system. The wireless power transmission system experiences control difficulty because the transmitter-side controller cannot directly measure the receiver-side load voltages and currents. Therefore, a control-oriented circuit model that shows the dynamics of the IPT system is required to achieve a well-behaved controller. In this study, an equivalent circuit model of the SP-IPT system in a synchronously rotating reference frame is proposed using the single-phase DQ transformation technique. The proposed circuit model is helpful in modeling the dynamics of the voltages and currents of the transmitter- and receiver-side resonant tanks and loads. The proposed circuit model is evaluated using frequency- and time-domain simulation results.

Analysis and Optimization of Wireless Power Transfer Efficiency Considering the Tilt Angle of a Coil

  • Huang, Wei;Ku, Hyunchul
    • Journal of electromagnetic engineering and science
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    • v.18 no.1
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    • pp.13-19
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    • 2018
  • Wireless power transfer (WPT) based on magnetic resonant coupling is a promising technology in many industrial applications. Efficiency of the WPT system usually depends on the tilt angle of the transmitter or the receiver coil. This work analyzes the effect of the tilt angle on the efficiency of the WPT system with horizontal misalignment. The mutual inductance between two coils located at arbitrary positions with tilt angles is calculated using a numerical analysis based on the Neumann formula. The efficiency of the WPT system with a tilted coil is extracted using an equivalent circuit model with extracted mutual inductance. By analyzing the results, we propose an optimal tilt angle to maximize the efficiency of the WPT system. The best angle to maximize the efficiency depends on the radii of the two coils and their relative position. The calculated efficiencies versus the tilt angle for various WPT cases, which change the radius of RX ($r_2=0.075m$, 0.1 m, 0.15 m) and the horizontal distance (y=0 m, 0.05 m, 0.1 m), are compared with the experimental results. The analytically extracted efficiencies and the extracted optimal tilt angles agree well with those of the experimental results.

The characteristics of Resonant class ${\phi}_2$ Inverter for short range wireless power transmission (근거리 무선전력전송용 공진형 Class ${\phi}_2$ 인버터 동작 특성)

  • Yang, Hae-Youl;Park, Jae-Hyun;Kim, Chang-Sun
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.13-14
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    • 2011
  • The power conversion converter for driving the wireless power transfer system is can be into the two part of the DC power conversion rectifier and the high frequency dc-ac power conversion inverter. In this paper, The operating characteristics of the Class-${\Phi}_2$ resonant inverter have been investigated through by simulation and by experiment. It can be switched at a high frequency without the switching losses and the harmonics are reduced effectively due to the input LC filter. Its switching frequency is 1MHz and the input voltage is 96V which is the output voltage of LLC resonant converter. And its output peak voltage is 170V. The resonant inverter module operated at the commercial power source of 220V was built. And also the electromagnetic coupled resonance coils were designed for wireless power transfer with a 1MHz operating frequency. As a experimental result, the wireless power transmission was confirmed and it is varified the validity of the experiment.

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Design of the High Efficiency Wireless On-Board Charger for Electric Vehicles (전기자동차용 고효율 무선 온보드 충전기의 설계)

  • Tran, Duc-Hung;Vu, Van-Binh;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • 2015.11a
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    • pp.27-28
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    • 2015
  • In this paper a high efficiency wireless on-board charger for Electric Vehicle (EV) is proposed and the theoretical analysis based on the two-port network model to come up with suitable design for the battery charge application is presented. The proposed Wireless Power Transfer (WPT) method has adopted four-coil system with air core and its superior performance is proved by comparing it to the conventional two-coil system by the mathematical analysis. In addition, since the proposed WPT converter is able to operate at an almost constant frequency regardless of the load, CC/CV charge of the battery can be simply implemented. A 6.6kW prototype is implemented with 20cm air gap to prove the validity of the proposed method. The experimental results show that the dc to dc conversion efficiency of the proposed system achieves 97.08% at 3.7 kW.

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Evaluation of AC Resistance in Litz Wire Planar Spiral Coils for Wireless Power Transfer

  • Wang, Xiaona;Sun, Pan;Deng, Qijun;Wang, Wengbin
    • Journal of Power Electronics
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    • v.18 no.4
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    • pp.1268-1277
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    • 2018
  • A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot-Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.