Influence of Coil Structure and Operating Frequency on Performance of Superconducting Wireless Power Transfer

High-temperature superconducting (HTS) coil magnets possess extremely high quality factors, therefore having unique advantages when applied to wireless power transfer (WPT) systems especially under low-frequency conditions. The dependence of peak output power and transfer efficiency of an HTS WPT system on the operating frequency varies with the design of the coils because the structure of the coils significantly affects the resonant frequency and ac loss of the HTS WPT system. In this work, a high-power HTS WPT system, including the transfer characteristics under different coil structures, current-carrying conditions, and operating frequencies, has been investigated based on the finite-element simulation to find the optimized operating frequency band and coil structure. It has been found that the change of the inner radius and turn gap in both the solenoid and pancake coils induces a predictable transition frequency change. As the gap is varied, the transfer efficiency remains relatively constant for both coil types. However, for solenoids, reducing the gap value enhances the transferred power, whereas for pancake coils, increasing the gap value augments the transferred power. A transfer efficiency as high as 98.86% or more can be achieved under the optimal conditions.