High power transmission efficiency of wireless power transfer system using high-quality factor superconducting bulk coil

We developed a high-quality-factor high-temperature superconducting (HTS) bulk coil to increase the power transfer efficiency (PTE) of wireless power transfer (WPT) systems. We proposed the resonant frequency tuning by using the two sapphire substrates thickness of coil support. The configuration of a 65 mm diameter HTS bulk coil was optimized to a resonant frequency of 64 MHz. The measured quality factor of the HTS bulk coil was 9,431, which is 12 times that of the copper coil. At the transfer distance of 20 cm, the measured PTE of the WPT system using HTS bulk coils and one using copper coils were 74.8% and 20.6%, respectively.