A Novel REBCO Wire Structure That Improves Coil Quality Factor in MHz Range and its Effect on Wireless Power Transfer Systems

We have developed a structure consisting of two conventional REBCO wires that increases the quality factor of coils, and have simulated its effect on to wireless power transfer (WPT) systems. The proposed structure is used to reduce the conductor loss of the Hastelloy substrate. The conductor losses of the skin effect of the wires were reduced by not using a copper stabilizer and a silver overlayer. We investigated the effect of embedding the proposed structure in styrene foam on the coil quality factor and found that the foam reduced the quality factor due to its dielectric loss. We fabricated several different wire type spiral coils embedded in styrene foam and measured their quality factor at 300 and 77 K. The quality factor of the coil using the proposed structure was about 3.2 times that of one using copper wire at 300 K. We also simulated the power transfer efficiency of a WPT system using two coils with different quality factors for different distances between the coils. Use of a high-quality factor coil enabled the system to achieve a longer transfer range.