• 전력전자학회논문지
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• 제24권5호
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• pp.311-318
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• 2019

In general wireless power transfer systems (WPTSs), power transfer is controlled by the wireless communication between a transmitter (Tx) and a receiver (Rx). However, WPTS is difficult to apply in electronic products that do not have batteries, such as TVs. A WPTS with resonators based on a transformer of LLC series resonant converter is proposed in this study to eliminate wireless communication units between a Tx and an Rx. The proposed system operates at the boundary of the resonance frequency, and the required power can be stably supplied to authorized devices even though some misalignment occurs. Moreover, standby power standards for the electronic product can be satisfied.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.183-185
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• 2011

A multiple charging method for a wireless power transfer system (WPTS) in the near-field region is proposed. We analyzed the frequency characteristics of multiple receivers in the near-field region. The results suggested that the time division WPTS can achieve efficient and equal power transmission at multiple receivers. We conclude that this system has an advantage for charging multiple receivers.

• 한국정보전자통신기술학회논문지
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• 제15권1호
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• pp.8-13
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• 2022

본 논문에서는 RF (Radio Frequency) 에너지 하베스팅 센서 노드의 설계 방안과 CATV 망과 누설 동축 케이블 (leaky coaxial cable)을 활용한 센서 네트워크 구축 방안을 연구하였다. 센서 노드는 915MHz 주파수 대역에서 동작하는 WPTS (Wireless Power Transfer System) 전력 수신기로 전원공급부를 설계하였다. WOC (WiFi over Coax) 기술을 활용하여 CATV 망으로 센서의 BLE 무선통신 신호와 WPTS 전력 송신기 신호를 전송하고, 누설 동축 케이블로 RF 신호를 방사시키는 센서 네트워크 구축 방안을 제안하였다. 센서 네트워크를 구축하는 지점에 누설 동축 케이블을 활용하면 센서 노드의 수신 신호 강도 지표가 허용되는 최소값 (-78dBm)을 만족하는 지점까지 센서 네트워크의 커버리지를 확장할 수 있다.

• Journal of electromagnetic engineering and science
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• 제16권4호
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• pp.219-224
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• 2016

In this paper, coupled-mode theory (CMT) is used to obtain a transient solution analytically for a wireless power transfer system (WPTS) when unit energy is applied to one of two resonators. The solutions are compared with those obtained using equivalent circuit-based analysis. The time-domain CMT is accurate only when resonant coils are weakly coupled and have large quality factors, and the reason for this inaccuracy is outlined. Even though the time-domain CMT solution does not describe the WPTS behavior precisely, it is accurate enough to allow for an understanding of the mechanism of energy exchange between two resonators qualitatively. Based on the time-domain CMT solution, the critical coupling coefficient is derived and a criterion is suggested for distinguishing inductive coupling and magnetic resonance coupling of the WPTS.

• 한국전자파학회논문지
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• 제25권10호
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• pp.959-965
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• 2014

본 논문에서는 그 동안 서울대학교에서 수행된 무선 전력 전송 관련 몇 가지 기본적인 연구 결과를 요약 정리하였다. 첫 번째 고찰은 무선전력 전송의 물리적인 한계에 대한 것으로, 주어진 안테나(공진기)를 이용하여 주어진 거리에서 얻을 수 있는 전송효율의 한계를 구면파 모드 이론을 이용하여 구하는 것이다. 두 번째로, 무선 전력 전송에서 사용되는 전력원의 종류에 따른 무선 전력 전송 특성 변화를 연구한 것이다. 더불어, 무선 전력 전송 안테나 사이의 거리가 변할 때 효율적인 전력전송이 가능한 방법을 제안하는 것이다. 마지막으로, 그 동안 무선 전력 전송에서 불분명하게 사용된 자기 유도방식과 자기 공명 방식의 차이를 분명히 하고자 하였으며, 결합 모드 이론을 이용하여 정량적인 구별 기준을 제시하였다.

• 전력전자학회논문지
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• 제21권3호
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• pp.275-281
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• 2016

A novel bidirectional magnetic wireless communication system is proposed in this study. This system provides the communication capability between the source and load sides by high-frequency signal while wireless power is transferred. Contrary to the conventional wireless communication systems using complex IC circuit and active components, the proposed system is simply composed of passive components. It is practical and beneficial for environmental robustness, cost effectiveness, and simple implementation. The detailed static analysis of the proposed system for power and communication lines is established. The proposed system is experimentally verified, and results show that a 0.1 voltage gain for communication line is obtained while a 2.0 voltage gain for the power line is achieved. The proposed system is adequate for practical applications as it allows the inductive power transfer system to wirelessly and easily communicate between the source and load sides.

• 전력전자학회논문지
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• 제25권1호
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• pp.44-53
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• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.