• Journal of the Korea Convergence Society
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• v.4 no.1
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• pp.27-31
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• 2013

The fast-paced development in the field of wireless charger based on M2M, which is available anytime and anywhere, is being underway in accordance with the development of IT technology. Wireless charger technology in M2M has various security threats because it is based on wireless network. The purpose of this paper is to examine the threats of authentication and payment attacks based on wireless network attacks, and to propose the response technique that fit the situation of the wireless charger service by modifying the existing detecting authentication and payment through wireless charger.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.539-548
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• 2007

In the paper, a wireless charger with the function of auto-shutdown for fully implantale middle ear hearing devices (F-IMEHD) has been designed. The wireless charger can communicate with an implant module to be turned off automatically shutdown after an internal rechargeable battery has been fully-charged by electromagnetic coupling using two coils. For the communication with an implant module, the wireless charger uses the load shift keying (LSK) method. But, the variation of the mutual inductance due to the different distance between two coils can cause the communication error in receiving the fully-charged signal from an implant module. To solve the problem, the implemented wireless charger has a variable reference generator for LSK communication. The wireless charger generates proper level of the reference voltage for a comparator using an ADC (analog-to-digital converter) and a DAC (digital-to-analog converter). Through the result of experiment, it has been confirmed that the presented wireless charger can detect signals from implantable module. And wireless charger can stop generating electromagnetic flux after an implanted battery has been fully charged in spite of variable coil distance according to different skin thickness.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.142-144
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• 2019

Nowadays, multi-MHz wireless power transfer (WPT) system has received a great concern of study due to its desirable characteristics such as user convenience, system compact and better safety as compared to the conventional DC-DC with cord. This paper presents a solution for WPT Lithium Batteries charger with Constant Current (CC) and Constant Voltage (CV) charging process. The proposed system consists of a high frequency class D power amplifier, a pair of PCB coil, transformable high-order resonant network and a full-bridge rectifier. The charger can be implemented CC /CV charging profile thanks to automatic reconfigurable resonant compensator. Therefore, the battery can be fully charged without the help of an additional DC/DC converter. The simulation and 50W-6.78-MHz hardware experimental results are presented to verify the feasibility of the proposed method and to evaluate the performance of the proposed wireless battery charger.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.321-322
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• 2015

The aim of this paper is to propose a design method for the double-sided LCC compensation circuit for 6.6kW electric vehicle (EVs) wireless charger. The analysis and comparison with several compensation topologies such as SS, SP, PS, PP and the hybrid LCC compensation is presented. It has been found that the hybrid LCC compensation has superior performance in comparison with other topologies. The design procedure for the EV charger is presented and the PSIM simulation results are provided.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.90-96
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• 2014

This paper is about increasing transfer efficiency of wireless power transmission. The new method is proposed to detect the alignment of transmitter and receiver of wireless charger and so smart phone can display the position of wireless charging receiver on its LCD panel for the maximum charging efficiency. The previous method is only to show the transfer efficiency, but this method is to show not only the efficiency but also coordinates of receiver. The apparatus of the wireless charger is based on WPC(Wireless Power Consortium) standard and has planar air coil combined with magnet shield in Tx and Rx device so that the leakage flux is minimized on condition of under hundreds of kHz operating frequency. In this paper, it's showed that relation of magnet field and distance of each coils can be linearized and position information of Tx and Rx device is calculated thru trigonometry. Through the experiment, the obstacles of linearity are discovered and also showed that it can be optimized. and so the presented method is suitable for alignment detection method of Tx and Rx device in WPC wireless charger.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.566-572
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• 2020

In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.

• Journal of the Korean Magnetics Society
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• v.23 no.2
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• pp.68-76
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• 2013

Currently, wireless power transmission technology based on magnetic induction was employed in battery charger for smart phone application. The system consists of wireless power transmitter in base station and receiver in smart phone. Size and thickness of receiver was strictly limited in the newest smart phone. In order to achieve high efficiency of a tiny small wireless power receiver module, sub-millimeter thick electromagnetic wave shielding sheet having high permeability and Q was essential component. It was found that magnetic field from transmitter to receiver can be intensified by sufficient shielding cause to minimize leakage magnetic flux by those magnetic properties. This leads to high efficiency of wireless power transmission and protects crucial integrated circuit of main board from electromagnetic noise. The important soft magnetic materials were introduced and summarized for the current small-power wireless power charger and NFC application and mid-power home appliance and high-power automotive application in the near future.

• 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.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.47-52
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• 2014

Recently, the interest of Wireless Power Transmission(WPT) has been increased for Mobile device application. It is necessary to analyze interference between wireless devices for the efficient use of frequency resource. The Minimum Coupling Loss(MCL) method and the Monte Carlo(MC) method were used for the interference analysis. In this paper, the impact of the 3rd order harmonics of the wireless charger for Cellular Phone on the existing Radio Modem was analyzed. As a result, the separation distance and the allowable number of interferer on the basis of service radius were obtained to protect the Radio Modem from the wireless charger for Cellular Phone.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.134-139
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• 2017

In this study, an inductive power transfer (IPT) charger for electric vehicles is proposed to improve the entire system efficiency and power density by eliminating the DC-DC converter in the secondary side. In the proposed IPT charger, the DC-link voltage is adjusted according to the coupling coefficient through cascade buck-boost converter in the front-end side, and the bridgeless rectifier performs the charging of battery. The control algorithm for the proposed IPT system is theoretically explained, and the validity of the proposed system is verified by informative simulation.