1. A Simple Wireless Power Charging Antenna System: Evaluation of Ferrite Sheet.
- Author
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Lee, Woncheol, Hong, Yang-Ki, Park, Jihoon, Lee, Jaejin, Baek, In-Seung, Hur, Nam-Pal, Seong, Won-Mo, and Park, Seong-Ook
- Subjects
ANTENNAS (Electronics) ,FERRITES ,MAGNETIC flux leakage ,PERMEABILITY ,MAGNETIC noise - Abstract
We report a simple wireless power charging (WPC) antenna system (50 mm \times40 mm \times0.1 mm) for use in simulating power transfer efficiency ( \eta ) with and without ferrite and a metallic object (battery case), thereby identifying suitable magnetic parameters and ferrite sheet thickness. The simulation results suggest that magnetic loss tangent (tan ) and permeability ( \mu ' ) need to be less than 0.05 and higher than 125 at 13.56 MHz, respectively, to achieve at least 75% of the transfer efficiency ( \eta \mathrm {max} ) of the WPC antenna without ferrite and the metallic object. Accordingly, we have fabricated NixZn0.85–xCu0.15Fe2O4 (x = 0.32 – 0.38) spinel ferrites using a one-step sintering process and obtained relatively high \mu ' of 169 and low tan \delta \mu of 0.1 with a nickel (Ni) concentration of 0.38. This magnetic loss is still too high to achieve 75% of the \eta \mathrm {max} value. In order to further reduce the magnetic loss, a two-step sintering process was used. The two-step sintered Ni0.38Zn0.47Cu0.15Fe2O4 shows $\mu '$ of 132 and a tan \delta \mu of 0.03 at 13.56 MHz, respectively. Therefore, this ferrite meets criteria identified by the transfer efficiency simulation and is a good candidate for 13.56-MHz wireless power transfer charging antenna system. In addition, our designed WPC system is capable of evaluating other magnetic materials that are suitable for WPC antenna applications. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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