Wireless Power Transfer between Two Self-Resonant Coils over Medium Distance Supporting Optimal Impedance Matching Using Ferrite Core Transformers

Jinwook Kim, Do-Hyeon Kim, Jieun Kim and Young-Jin Park
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Jinwook Kim: 3M Electronics Materials Solutions Division, 3M Korea, Hwaseng 18449, Korea
Do-Hyeon Kim: Samsung Electronics, Suwon 16677, Korea
Jieun Kim: Electro-Medical Research Center, Korea Electrotechnology Research Institute, Ansan 15588, Korea
Young-Jin Park: Electro-Medical Research Center, Korea Electrotechnology Research Institute, Ansan 15588, Korea

Energies, 2021, vol. 14, issue 24, 1-15

Abstract: An efficient wireless power transfer (WPT) system is proposed using two self-resonant coils with a high-quality factor (Q-factor) over medium distance via an adaptive impedance matching network using ferrite core transformers. An equivalent circuit of the proposed WPT system is presented, and the system is analyzed based on circuit theory. The design and characterization methods for the transformer are also provided. Using the equivalent circuit, the appropriate relation between turn ratio and optimal impedance matching conditions for maximum power transfer efficiency is derived. The optimal impedance matching conditions for maximum power transfer efficiency according to distance are satisfied simply by changing the turn ratio of the transformers. The proposed WPT system maintains effective power transfer efficiency with little Q-factor degradation because of the ferrite core transformer. The proposed system is verified through experiments at 257 kHz. Two WPT systems with coupling efficiencies higher than 50% at 1 m are made. One uses transformers at both Tx and Rx; the other uses a transformer at Tx only while a low-loss coupling coil is applied at Rx. Using the system with transformers at both Tx and Rx, a wireless power transfer of 100 watts (100-watt light bulb) is achieved.

Keywords: optimal impedance matching; ferrite core transformer; magnetically coupled resonance; wireless power transfer; impedance matching (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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