• Title, Summary, Keyword: Contactless transformer

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Analysis of the Contactless Power Transfer System Using Modeling and Analysis of the Contactless Transformer

  • Ryu Myung-Hyo;Kim Jong-Hyun;Baek Ju-Won;Cha Hon-Nyong
    • Journal of Electrical Engineering and Technology
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    • v.1 no.3
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    • pp.351-358
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    • 2006
  • In this paper, the electrical characteristics of the contactless transformer is presented using the conventional coupled inductor theory. Compared with the conventional transformer, the contactless transformer has a large airgap, long primary wire and multi-secondary wire. As such, the contactless transformer has a large leakage inductance, small magnetizing inductance and poor coupling coefficient. Therefore, large magnetizing currents flow through the entire primary system due to small magnetizing inductance, resulting in low overall system efficiency. In high power applications, the contactless transformer is so bulky and heavy that it needs to be split by some light and small transformers. So, the contactless transformer needs several small transformer modules that are connected in series or parallel to transfer the primary power to the secondary one. This paper shows the analysis and measurement results of each contactless transformer module and comparison results between the series- and parallel-connection of the contactless transformer. The results are verified on the simulation based on the theoretical analysis and the 30kW experimental prototype.

Design and Analysis of A Rectangular Type Core for A Contactless Power Transmission system (비접촉 진력전송 시스템을 위한 'ㅁㅓ'형 코어 설계 및 분석)

  • Jin, Kang-Hwan;Kim, Ji-Min;Kim, Soo-Hong;Kim, Eun-Soo;Kim, Yoon-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.1
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    • pp.52-57
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    • 2008
  • In the transformer that is used for the contactless power transmission system, the primary and secondary sides are separated structurally unlike general transformers. When the contactless transformer is built, it forms relatively bigger air gap than the general transformer. Thus it is difficult to transfer energy from the primary side input to the secondary side output with high power efficiently because of low coupling coefficient. This paper proposes a contactless transformer using the rectangular type core that maintains high coupling coefficient even when it has relatively large air gap. The performance characteristics of the proposed transformer are compared with the transformer using general EE core to the air gap variation. The proposed contactless system using rectangular type core and dc-dc full bridge converter, and the system using EE core type and dc-dc full bridge converter are respectively implemented and their performance characteristics are verified by the simulation and experiment.

Study on resonant frequency tracking for contactless power system using multiple primary winding contactless transformer (다중일차권선 비접촉변압기를 이용한 비접촉 전원시스템의 공진주파수 추적에 관한 연구)

  • Kim, Yoon-Ho;Rho, Sung-Chan
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.3
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    • pp.182-188
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    • 2006
  • Contactless power system is base on power transmission by magnetic force. The transformer loss is large because it separated with the gap. Also the system has unstable factor, since the parameters in the secondary can vary with the system movement. This paper proposes light train power transmission system using contactless transformer with multiple primary winding. To increase the system efficiency and to obtain the stable power transmission to the dynamic load, a resonant inverter is adopted. The proposed system was verified by the simulation using Spice and Maxwell. The designed contactless power transmission system is implemented for 5[kW] class and experimental results are discussed.

A Contactless Energy Transfer Circuit Using Coreless Low-profile PCB Transformer (코어없는 초박형 PCB 변압기를 이용한 무접점 전력변환 회로)

  • 최병조
    • Proceedings of the KIPE Conference
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    • pp.505-508
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    • 2000
  • A coreless printed circuit board(PCB) transformer is employed in a contactless energy transfer circuit that achieves an efficient power conversion at the presence of a considerable airgap between the source and the load side. A half-bridge series resonant converter is selected as the contactless energy transfer circuit in order to minimize the detrimental effects of large leakage inductance small magnetizing inductance and poor coupling coefficient of the coreless PCB transformer. The operation and performance of the proposed contactless power converter are verified on a 7 W experimental circuit that provides an 18V/0.4A output from a 210-370 V input source.

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An Improved High Efficiency Resonant Converter for the Contactless Power Supply with a Low Coupling Transformer (낮은 커플링 변압기를 갖는 비접촉 전원의 개선된 고효율 공진 컨버터)

  • Kong Young-Su;Kim Eun-Soo;Lee Hyun-Kwan
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.1
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    • pp.33-39
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    • 2005
  • Comparing with the conventional transformer without the air gap, a contactless transformer with the large air gap between the long primary winding and the secondary winding has increased leakage inductance and reduced magnetizing inductance. For transferring the primary power to the secondary one, the high frequency series resonant converter has been widely used for the contactless power supply system with the large air gap and the increased leakage inductance of the contactless transformer However, the high frequency series resonant converter has the disadvantages of the low efficiency and high voltage gain characteristics in the overall load range due to the large air gap and the circulating magnetizing current. In this paper, the characteristics of the high efficiency and unit voltage gain are revealed in the proposed three-level series-parallel resonant converter. The results are verified on the simulation based on the theoretical analysis and the 5kW experimental prototype.

Numerical Analysis and Design of Moving Contactless High Power Transformer

  • Lee, Dong-Su;Jang, Dong-Uk;Kim, Hyung-Chul;Jung, Sang-Yong
    • Journal of Magnetics
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    • v.16 no.4
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    • pp.423-426
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    • 2011
  • This paper presents numerical analysis and design of high power contactless transformer with a large air-gap for moving on a guided linear track which is appropriate for high-speed train or MAGLEV. The system has the typical characteristics of large leakage inductance, small magnetizing inductance, and low coupling coefficients giving rise to lower power transfer efficiency, which have been compensated by the purposely-designed contactless transformer coupled with the resonant converter modulating with high switching frequency. In particular, the best model selected from the generated six design candidates has been applied for 3D Finite Element Analysis (FEA) investigating on iron loss to evaluate the overall system efficiency.

Contactless Power Transfer System using Voltage Phase (전압위상을 이용한 무접점 전원공급 시스템에 관한 연구)

  • Yu, Joo-Hee;Kim, Choon-Sam
    • The Transactions of the Korean Institute of Power Electronics
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    • v.16 no.3
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    • pp.219-226
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    • 2011
  • As the existing contactless power transfer system(CPTS) is adopting the principle of contactless transformer enables to supply power in contactless way using RFID(radio frequency identification)/ID communication method between primary and secondary sides of contactless transformer and detect the alien load. Such CPTS requires the circuit that generates ID in addition, and the ID identification and control generated from the secondary side is performed at the primary side, which cuases complexity of the circuit. Therefore, this study suggested the CPTS using voltage phase, and In order to verify the validity of this study, 3[W] class CPTS shall be designed, and the simulation and test of CPTS using current and voltage phases shall be carried out.

Characteristics of the ㄷ ㅓ Type Core for Contactless Battery Charger (비접촉식 충전 장치를 위한 ㄷㅓ 형 코어에 관한 연구)

  • Jeon, Sung-Jeup;Heo, Jun;Lee, Kwang-Woon;Cho, Kyu-Hyung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.8 no.5
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    • pp.407-417
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    • 2003
  • Detachable transformers used in contactless battery chargers have poor power transfer characteristics because they have low coupling coefficients due to their gaps. The ㄷㅓ type core gives a high coupling coefficient in a contactless battery charger compared with standard cores such as EE, EC and UU. In this paper, characteristics of the ㄷㅓ type core is studied. Detailed analyses and comparisons are given based on the sinusoidal operation and square-wave operation. Reductions in output current, voltage and power are stated analytically and numerically. The analyses are verified by experiments conducted on a ZVS converter including a detachable transformer. The analyses and comparison method can be applied to other gaped transformer such as a PCB transformer.

A Contactless Power Supply for a DC Power Service

  • Kim, Eun-Soo;Kim, Yoon-Ho
    • Journal of international Conference on Electrical Machines and Systems
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    • v.1 no.4
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    • pp.483-491
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    • 2012
  • It is expected that, in the future, DC power service will be widely used for photovoltaic home power generation systems, since DC consuming devices are ever increasing. Instead of using multiple converters to convert DC to AC and then AC to DC, the power service could solely be based on DC. This would eliminate the need for converters, reducing the cost, complexity, and possibly increasing the efficiency. However, configuration of direct DC power service with mechanical contacts can cause spark voltage or an electric shock when the switch is turned on and off. To solve these problems, in this paper, a contactless power supply for a DC power service that can transfer electric power produced by photovoltaics to the home electric system using magnetic coupling instead of mechanical contacts has been proposed. The proposed system consists of a ZVS boost converter, a half-bridge LLC resonant converter, and a contactless transformer. This proposed contactless system eliminates the use of DC switches. To reduce the stress and loss of the boost converter switching devices, a lossless snubber with coupled inductor is applied. In this paper, a switching frequency control technique using the contactless voltage sensing circuit is also proposed and implemented for the output voltage control instead of using additional power regulators. Finally, a prototype consisted of 150W boost converter has been designed and built to demonstrate the feasibility of the proposed contactless photovoltaic DC power service. Experimental results show that 74~83% overall system efficiency is obtained for the 10W~80W load.

Characteristic analysis of inductive contactless power transformer used for the road/railway to improve the performance. (도로/궤도 매립형 무접촉 집전장치의 전력전달 성능 개선을 위한 특성해석)

  • Han K.H.;Baek S.H.;Lee B.S.;Bae C.H.;Byun Y.S.
    • Proceedings of the KIEE Conference
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    • pp.1304-1306
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    • 2004
  • Recently, the study for development of system having affinity for environment is on investigation. This issue is also applicable to transportation system. This paper suggested the inductive power transformer used for the road/railway applied to contactless power transfer system. The two secondary windings, large gaped magnetic structure and horizontal alignment between primary and secondary coil for that transformer approach a process for improvement of contactless power transfer system performance.

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