• Journal of Electrical Engineering and Technology
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• 제1권3호
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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.

• 전기학회논문지
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• 제57권1호
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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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권3호
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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.

• 전력전자학회논문지
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• 제16권3호
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• pp.219-226
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• 2011

기존의 무접점 전원공급 시스템은 비접촉 변압기의 1, 2차측 간 RFID/ID 통신 방식을 이용하여 무접점으로 전원을 공급하고, 이물질을 감지한다. 이러한 시스템은 ID 신호를 발생시켜주는 회로가 추가 되어야 하고, 2차측에서 발생한 ID 신호의 인식과 제어는 1차측에서 수행하기 때문에 회로의 복잡성이 야기된다. 따라서 본 논문에서는 전압위상을 이용한 무접점 전원공급 시스템을 제안하고, 타당성을 증명하기 위하여 3[W]급 무접점 전원공급 장치를 설계하고, 시뮬레이션 및 실험을 수행하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.713-716
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• 2003

In recent, the contactless IC card is widely used in traffic, access control system and so forth. Contactless smart cards use a technology that enables card readers to provide power for transactions and communications without making physical contact with the cards. Usually electromagnetic signal is used for communication between the card and the reader. Contactless card is highly suitable for large quantity of card access and data transaction. And its use becomes a general tendency more and more because of the development of RF technology and improvement of requirement for user convenience. This paper describes the hardware module to process contactless protocol for implementation contactless IC card. And the hardware module consists of specific digital logic circuits that analyze digital signal from analog circuit and then generate data & status signal for CPU, and that convert the data from CPU into digital signal for analog circuit.

• 패션비즈니스
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• 제26권3호
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• pp.1-18
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• 2022

The COVID-19 pandemic has not only increased customer preference for contactless methods but also created digital business opportunities in a variety of industries. Particularly in the fashion industry, contactless distribution and contactless shopping have increased significantly. This study identifies the changed consumers' perception of contactless shopping, which has been expanded due to the COVID-19 pandemic and analyzes specific factors that influence shopping switching intention to derive efficient marketing plans for post COVID-19 era. The study targeted Korean male and female consumers. The perceived value, usefulness, and alternative attractiveness of contactless shopping had a significant effect on shopping switching intention, and a moderating effect of offline fashion stores was confirmed. These results indicate that customers' experience in a fashion store influences their next online and offline shoping. This study, therefore, proposed the direction that the fashion industry should advance from a marketing perspective in the post COVID-19 era.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.272-274
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• 2003

This paper investigates contactless power transfer system for electric railway which makes use of electromagnetic induction among the coils. The transmission line efficiency and the quality factor are introduced to analyze the performance of the contactless power transfer system. Several instances of the mobile loads using contactless power transmission are described to understand practical usefulness.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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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.

• 조명전기설비학회논문지
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• 제22권2호
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• pp.80-84
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• 2008

본 논문은 다중권선의 비접촉 변압기를 이용한 비접촉 전력공급 방식을 제안한 논문이다. 논문에서 제안한 전력공급 방식은 엘리베이터 카에 신뢰성 높은 전력을 전송하기 위하여 공진주파수 추적 기법을 사용하였다. 제안된 시스템을 검증하기 위하여 ICAP4와 Maxwell을 사용하여 시뮬레이션을 수행하였으며, 5[kW]급 비접촉 전력전송시스템을 제작하여 실험을 수행하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.40-46
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• 2012

This paper presents contactless power supply systems using the Valtchev model in transportation systems. The major drawback of contactless systems is that the efficiency is lower than that of contact systems. The coupling coefficient of the contactless transformer is the most influential parameter on the system efficiency. Here, a new computer model for the contactless transfer system developed in the Korea Railroad Research Institute is presented. Also, simulations of the old model and the new model are compared with the prototype measurement to assure the model validity.