Analysis and Performance Improvement of Independent Electric Coupled Resonance WPT System with Impedance Transformer

Cheng YANG  Koichi TSUNEKAWA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.4   pp.630-637
Publication Date: 2015/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.630
Type of Manuscript: PAPER
Category: Antennas and Propagation
Keyword: 
wireless power transfer,  electric coupled resonance,  equivalent circuit,  impedance matching,  

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Summary: 
Wireless power transfer (WPT) based on electric coupled resonance can withstand a great level of variability in antenna separation. In this paper, we propose an independent electrical coupled resonance WPT system to further increase such systems' power transfer distance and ensure flexibility in the antenna location. The proposed system's power transfer function, critical coupling point, and resonance frequency splitting are investigated via the equivalent circuit, simulation, and experiment. Moreover, the input impedance characteristic of two electric coupled resonance antennas is also analyzed according to the transfer distance. In the region of under coupled, an appropriate impedance matching method is required to achieve effective power transfers. Here, we proposed a fixed configuration type matching loop with a series-connecting variable capacitance that can be added into both the source and load antennas. Experimental results demonstrate that the proposed matching loop can convert the two electric coupled resonance antennas' input impedance to the feed port impedance very well at varying transfer distances; these results are in good agreement with the simulation results.