전력전송거리 증가를 위한 구형 자속 집중 송신부 구조의 설계 및 해석

박광록,차화랑,김래영,김태진 전력전자학회 2020 전력전자학회 논문지 Vol.25 No.3

In this study, we propose a spherical flux concentration structure for omnidirectional wireless power transfer. Omnidirectional wireless power transfer technology is a method that can transmit power to a transmitter located in an arbitrary position in a two-dimensional or three-dimensional space. However, to improve the power transfer distance in a wireless power transfer system, the diameter of the coil or the number of windings must increase, thereby increasing the size of the transmitter. The proposed transmitter structure adds a ferrite core inside the transmitter coil so that the magnetic flux generated by the transmitter is directed toward the position of the receiver. As a result, the flux linkage and the mutual inductance increase. By implementing the omnidirectional wireless power transfer system using the proposed structure, the power transfer distance can be improved by 65% ​​compared with the conventional system without increasing the size of the transmitter. Simulation shows that the proposed spherical flux concentration structure increases the mutual inductance of the omnidirectional wireless power transmission system.

Wireless Power Transfer-Based Microrobot with Magnetic Force Propulsion Considering Power Transfer Efficiency

김동욱,안승영 한국전자파학회 2022 Journal of Electromagnetic Engineering and Science Vol.22 No.4

A microrobot that could continuously receive both electrical energy and propulsion force from a wireless power transfer system would offer tremendous benefits. However, wireless powering systems produce a time-varying magnetic field that can be harmful if the generated magnetic field needed for microrobot movement is large. To limit exposure, power transfer efficiency must be enhanced. This paper derived and analyzed the magnetic force applied to a microrobot from a wireless power transfer system. Unlike previously introduced Lorentz force-based microrobot propulsion, the proposed method is independent of a wireless power transfer system’s frequency. Therefore, this frequency can be determined considering maximum power transfer efficiency. The theoretical analysis and simulation by numerical analysis were compared, and results were verified though actual fabrication and measurement. Analyses of the transmitting and receiving coils were conducted. The optimum force, with less than 9% discrepancy, was determined while achieving a 3.6% improvement in power transfer efficiency.

Wireless Synchronous Transfer of Power and Reverse Signals

Li, Yang,Li, Yumei,Feng, Shaojie,Yang, Qingxin,Dong, Weihao,Zhao, Jingtai,Xue, Ming The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Wireless power transfer via coupled magnetic resonances has been a hot research topic in recent years. In addition, the number of related devices has also been increasing. However, reverse signals transfer is often required in addition to wireless power transfer. The structure of the circuit for a wireless power transfer system via coupled magnetic resonances is analyzed. The advantages and disadvantages of both parallel compensation and series compensation are listed. Then the compensation characteristics of the inductor, capacitor and resistor were studied and an appropriate compensation method was selected. The reverse signals can be transferred by controlling the compensation of the resistor. In addition, it can be demodulated by extracting the change of the primary current. A 3.3 MHz resonant frequency with a 100 kHz reverse signals transfer system platform was established in the laboratory. Experimental results demonstrate that wireless power and reverse signals can be transferred synchronously.

레이저 무선충전 기술 연구

이동훈,김성만 한국전자통신학회 2016 한국전자통신학회 논문지 Vol.11 No.12

현재까지 개발된 무선 충전기술은 크게 전자기유도 방식, 자기공명 방식, 전자기파 방식 등이 있다. 하지만 기존의 방법들은 전송거리가 짧거나 전자파 장해를 일으키는 문제를 가지고 있다. 이러한 문제점을 해결하기 위하여 본 논문에서는 레이저를 이용한 무선충전 기술에 대해 연구하고 이에 대한 실험결과를 보인다. 이 기술은 송신단에 전/광 변환을 위한 레이저 광원을 사용하여 빛의 형태로 에너지를 무선으로 전송하며, 수신단에는 광/전 변환을 위해 태양전지나 PD(: Photo Diode)를 이용하는 방식이다. 10m 이상의 장거리에서는 레이저 무선충전 기술의 전송효율이 가장 높을 것으로 전망되며, 장거리 무선충전에서는 레이저 무선충전 기술이 가장 효율적인 무선충전 기술이 될 것으로 판단된다. 본 논문의 실험결과에서는 100 mW Red 레이저 송신부와 PD 수신부를 이용하여 70 m의 장거리 전송거리에서 DC-to-DC 로 2.15 %의 무선전력전송 효율을 보였다. The current wireless power charge technologies are based on induction coupling, magnetic resonant coupling, electromagnetic wave, etc. However, the current wireless power charge technologies has several disadvantages including short transfer range, electromagnetic interference, etc. In this paper, we investigate and demonstrate a laser wireless power charge technology. A laser source is used in the transmitter to convert from electric power to optical power and a solar cell or a photodiode is used in the receiver to convert from optical power to electric power. The laser wireless power charge technology may be the most efficient wireless power charge technology in the long distance over than 10 meters. Our experimental results show a transfer efficiency of 2.15% at the 70-m long distance with a 100 mW laser transmitter and a photodiode receiver.

Feasible Study of Wireless Power Charging System for EDS-Based Superconducting Magnetic Levitation Train Using HTS Receiver

Yoon Do CHUNG,Chang Young LEE 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Recently, the wireless power transfer (WPT) systems have started to be applied to the wireless charging for electrical vehicles and trains because of their advantages compared with the wired counterparts, such as convenience, safety, and fearless transmission of power. However, it has obstacles to commercialize to large power deliver and efficiency in WPT technology. This paper presents the feasibility of technical fusion between wireless power transfer (WPT) system and superconducting magnet technology to enable to charge large power into very low temperature circumstance of superconducting magnet for high speed magnetic levitation (MAGLEV) train without any connector or wire. The superconducting magnet in high speed MAGLEV train system maintains keeps stronger magnetic field that plays a role to sustain stable levitation gap. Generally, the superconducting magnet has been supplied by conventional electric power persistently to keep fixed levitation gap and low irregularity tolerance. However, a large thermal loss is indispensably caused by power transfer wires. Fortunately, since superconducting wires have a higher Q-value intrinsically, transfer selectivity and distance between antenna and receiver coils can be improved easily. Thus, the superconducting receiver (Rx) coil for superconducting magnet can be expected as a reasonable option to deliver large power with high efficiency. In this paper, we designed and investigated wireless power transfer system for the wireless power charging system for superconducting Maglev (WPC4SM) using high temperature superconducting (HTS) receiver. To confirm the capacity of HTS Rx coil, we compared with operating efficiency using normal conducting Rx coil. As a result of investigation, the transfer efficiency with HTS receiver could be successfully improved over 30 % compared with copper receiver at laboratory scale with a purpose built test stand.

Wireless Synchronous Transfer of Power and Reverse Signals

Yang Li,Yumei Li,Shaojie Feng,Qingxin Yang,Weihao Dong,Jingtai Zhao,Ming Xue 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Wireless power transfer via coupled magnetic resonances has been a hot research topic in recent years. In addition, the number of related devices has also been increasing. However, reverse signals transfer is often required in addition to wireless power transfer. The structure of the circuit for a wireless power transfer system via coupled magnetic resonances is analyzed. The advantages and disadvantages of both parallel compensation and series compensation are listed. Then the compensation characteristics of the inductor, capacitor and resistor were studied and an appropriate compensation method was selected. The reverse signals can be transferred by controlling the compensation of the resistor. In addition, it can be demodulated by extracting the change of the primary current. A 3.3 MHz resonant frequency with a 100 kHz reverse signals transfer system platform was established in the laboratory. Experimental results demonstrate that wireless power and reverse signals can be transferred synchronously.

Design Considerations of Superconducting Wireless Power Transfer for Electric Vehicle at Different Inserted Resonators

Yoon Do Chung,Chang Young Lee,Hyoungku Kang,Young Gun Park IEEE 2016 IEEE transactions on applied superconductivity Vol.26 No.4

<P>The wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air. Recently, the WPT systems have started to be applied to the wireless charging for electrical vehicles (EVs) because of their advantages compared with the wired counterparts, such as convenient, safety, and fearless transmission of power. However, there are challenges in its commercialization, such as delivery distance and efficiency. To solve the problems, we proposed the technical fusion using high-temperature superconducting (HTS) resonance coil in the WPT system, which is called superconducting wireless power transfer for electric vehicle (SUWPT4EV) system. Since the superconducting wire has merits, i.e., a larger current density and a higher Q value than normal conducting wire, the HTS antenna coil enables to deliver a mass amount of electric energy in spite of a small-scale antenna, as well as is possible to keep much stronger magnetic fields out in the peripheral regions. Thus, the SUWPT4EV system has been expected as a reasonable option to improve the transfer efficiency of large electric power. In this study, as an advanced approach, we proposed the advanced SUWPT4EV system with inserted resonator using noncooled copper, cooled copper, and HTS resonators, respectively, in order to expand the transfer distance and improve the transfer ratio. In this paper, we presented operating characteristics of the advanced SUWPT4EV system and achieved the improvement and effects of transmission power for inserted resonators within 40-cm distance under radio frequency power of 370 kHz below 600 W.</P>

Loss Analysis and Power Improvement of Non-resonant Type Capacitive Power Transfer System With Three-level Operation

T. Kitabayashi,H. Funato,J. Haruna,Y. Tsuruta,K. Yamaichi 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The authors have proposed a new capacitive power transfer (CPT) system using one-pulse switching active capacitor (OPSAC). The proposed system improves transfer power without LC resonance so that it is robust against parameter change. The one of advantages of OPSAC is easy realization of cascade connection in order to enhance transfer power. In the past, CPT system with five-stage OPSAC was successfully realized, but the actual transfer power was smaller than theoretical power. In this paper, loss factor is analyzed using precise calculation model. In addition, from the results of loss analysis, it was clarified that the one of the main loss factor is diodes of rectifier so that the system using synchronous rectifier is also proposed for power improvement.

Uniform Power I-Type Inductive Power Transfer System With <i>DQ</i>-Power Supply Rails for On-Line Electric Vehicles

Changbyung Park,Sungwoo Lee,Seog Yong Jeong,Gyu-Hyeong Cho,Rim, Chun T. Institute of Electrical and Electronics Engineers 2015 IEEE transactions on power electronics Vol. No.

<P>A narrow-width power-invariant inductive power transfer system (IPTS) along the driving direction is newly proposed in this paper. The conventional I-type power supply rail for on-line electric vehicles (OLEVs) has a very narrow power supply rail with 10-cm width and exposes pedestrians to a very low electromagnetic field due to its alternatively arranged magnetic poles along the driving direction of electric vehicles; however, it has a major drawback: Sinusoidal variation of the induced pick-up voltage depending on pick-up positions on the power supply rail along driving direction. To overcome this disadvantage, a dq-power supply rail fed by two high-frequency ac currents of the d-phase and q-phase is introduced in this paper. The d -phase and q-phase magnetic poles are alternatively arranged in a line; hence, the induced voltage of a pickup becomes spatially uniform. The power invariant characteristic of the proposed IPTS for OLEV has been verified by analysis, simulations, and experiments. A practical winding method is suggested as well.</P>

Reconfigurable Wireless Power Transfer System for Multiple Receivers

Chung G. Kang,Seung-Min Lee,Moon-Que Lee,Sun-Han Hwang 한국전자파학회JEES 2016 Journal of Electromagnetic Engineering and Science Vol.16 No.4

We present a novel schematic using a 3-dB coupler to transmit radiofrequency (RF) power to two receivers selectively. Whereas previous multiple receiver supporting schemes used hardware-switched methods, our scheme uses a soft power-allocating method, which has the advantage of variable power allocation in real time to each receiver. Using our scheme, we can split the charging area and focus the RF power on the targeted areas. We present our soft power-allocating method in three main points. First, we propose a new power distribution hardware structure using a FPGA (field-programmable gate array) and a 3-dB coupler. It can reconfigure the transmitting power to two receivers selectively using accurate FPGA-controlled signals with the aid of software. Second, we propose a power control method in our platform. We can variably control the total power of transmitter using the DC bias of the drain input of the amplifier. Third, we provide the possibility of expansion in multiple systems by extending these two wireless power transfer systems. We believe that this method is a new approach to controlling power amplifier output softly to support multiple receivers.