Loosely-coupled wireless power transfer: Physics, circuits, standards

Grajski, Kamil A.; Tseng, Ryan; Wheatley, C.E.

doi:10.1109/imws.2012.6215828

Cited by 40 publications

(16 citation statements)

References 16 publications

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“…The WPT technique is expected to be useful for various applications such as cellular phones, laptop computers, home electrical appliances, and electric vehicles [2][3][4][5][6]. The convenience of power transfer in this manner is analogous to the difference between wireless and wired communication.…”

Section: Introductionmentioning

confidence: 99%

Misaligned Effect and Exposure Assessment for Wireless Power Transfer System Using the Anatomical Whole-Body Human Model

Park

2017

PIER C

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Abstract-This paper presents dosimetry of a high resonance wireless power transfer (HR-WPT) system when the transmitter and receiver are aligned and misaligned. An HR-WPT system with two resonant coils and two feeding loops, operating at 13.56 MHz is designed. The power transfer efficiency of the system, and the electric and magnetic fields are investigated using the method of moments. The power transfer efficiency in misalignment situations can be increased by matching the HR-WPT system. Dosimetry of the HR-WPT system is conducted at the optimum matching condition for alignment and misalignment, to achieve the best power transfer efficiency. The specific absorption rate (SAR) is computed using a two-step approach. In the first step, the magnetic fields generated by the HR-WPT system in the absence of a whole-body voxel human model are calculated using the method of moments. In the second step, the SAR in the human model is calculated using the impedance method, with the magnetic fields computed in the previous step regarded as the magnetic fields incident to the human body. Five exposure scenarios are set: one alignment condition and four misalignment conditions. The SAR computed for the alignment and misalignment cases in the matching condition are compared to each other. The compliance of the system is also investigated using the international safety guidelines. Finally, the maximum allowable powers to comply with the guideline are investigated for the five cases considered. The results show that the SARs observed in the misalignment case are higher than those in the alignment case. These results suggest that the misalignment situation should be considered in addition to alignment, when conducting dosimetry of the HR-WPT system.

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Section: Introductionmentioning

confidence: 99%

Misaligned Effect and Exposure Assessment for Wireless Power Transfer System Using the Anatomical Whole-Body Human Model

Park

2017

PIER C

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“…From various studies [11][12][13], we know that C p is selected to create an imaginary part to zero in order to deliver the maximum power to the load, while C s is selected as a value that satisfies the optimal resonant frequency. Fig.…”

Section: Tx-rx Matching Designmentioning

confidence: 99%

Reconfigurable Wireless Power Transfer System for Multiple Receivers

Hwang¹,

Kang²,

Lee

et al. 2016

Journal of electromagnetic engineering and science

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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. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

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“…Considering the value of load resistor R should be higher than parasitic resistance of L2 to reduce the power loss in the inductor, a 10 Ω load resistor was used to be the initial condition for the equations listed in [3]. Selecting 240 kHz as the operating frequency, the other component values are L1 = 500 µH, C1 = 14.4 nF, C2 = 54 nF, L2 = 18 µH.…”

Section: High Performance Class-e Power Amplifiermentioning

confidence: 99%

“…[2,3] Among these technologies, electromagnetic coupling is the most suitable solution for LED lighting applications. It can achieve efficiency levels of at least 70% for distances of several millimeters to several centimeters between the transmitting and receiving coil.…”

Section: Introductionmentioning

confidence: 99%

“…That is because the Class-E power amplifier will be driven by a higher current, and the output power will dramatically increase when the biasing voltage is at the same condition. However, according to the equations listed in [3], the Class-E power amplifier needs a smaller C1 to operate normally when a smaller R is chosen. Therefore, a transistor with small parasitic capacitance C ds is a better choice to design a high output power…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A 36 W Wireless Power Transfer System with 82% Efficiency for LED Lighting Applications

Chen

Chinga

Yoshida

et al. 2013

Transactions of The Japan Institute of Electronics Packaging

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This paper presents the design and implementation of an LED lighting module powered by a wireless power transfer system. The overall system achieves an efficiency of 82% with an output power of 36 W when the load resistance in the receiver is 30 Ω, which is the turn-on resistance of the LED lighting module. The transmitter of the system adopts Class-E power amplifier structure instead of Class-D, to decrease the number of transistors and its cost. The coils of the system are designed by electromagnetic coupling methodology and realized by Litz wire to reach high efficiency. Matching circuits between the system blocks are also discussed in this paper in order to obtain the excellent system performance.

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Loosely-coupled wireless power transfer: Physics, circuits, standards

Cited by 40 publications

References 16 publications

Misaligned Effect and Exposure Assessment for Wireless Power Transfer System Using the Anatomical Whole-Body Human Model

Misaligned Effect and Exposure Assessment for Wireless Power Transfer System Using the Anatomical Whole-Body Human Model

Reconfigurable Wireless Power Transfer System for Multiple Receivers

A 36 W Wireless Power Transfer System with 82% Efficiency for LED Lighting Applications

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