A Novel Resonator Design for Q Factor Improvement Using Tightly-Coupled Parallel Coils in Coupled Magnetic Resonance Wireless Power Transfer

Cheng YANG  Koichi TSUNEKAWA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E99-B   No.3   pp.685-694
Publication Date: 2016/03/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3310
Type of Manuscript: PAPER
Category: Antennas and Propagation
Keyword: 
wireless power transfer,  coupled magnetic resonance,  resonator,  Q factor,  transfer efficiency,  

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Summary: 
This study proposes a novel resonator design that uses tightly coupled parallel coils to improve the quality factor (Q factor) in coupled magnetic resonance wireless power transfer. Depending on the characteristics of the tightly coupled parallel-connected coils, the proposed resonator can offer significantly reduced resistance with very little self-inductance loss. A double-layer spiral coil structure is used for resonator design and evaluating its characteristics. Measured results show that a resonator consisting of two identical, tightly coupled parallel double-layer spiral coils can match the Q factor of a conventional double-layer spiral coil with the same number of turns, even though its equivalent resistance is approximately 75% less. Moreover, the system power transfer performance of the resonator was measured under the impedance matching condition. To further reduce the resistance, we propose another resonator comprising of three parallel and tightly coupled double-layer spiral coils, and measure its equivalent resistance characteristics for different wire gap sizes.