Design Consideration and Efficiency Comparison of Wireless Power Transfer With HTS and Cooled Copper Antennas for Electric Vehicle

The wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air. Recently, the WPT systems have started to be applied to the wireless charging for electrical vehicles (EVs) because of their advantages compared with the wired counterparts, such as convenience, safety, and fearless transmission of power. However, it has obstacles to commercialize such as delivery distance and efficiency. To solve the problems, we proposed the technical fusion using a high-temperature superconducting (HTS) antenna in the WPT system, which is called superconducting WPT for electric vehicle (SUWPT4EV) system. Since the superconducting wire has the merits of a larger current density and higher Q value than a normal conducting wire, the HTS antenna enables to deliver a mass amount of electric energy in spite of a small-scale antenna. To apply copper-stabilizer HTS (GdBCO) coil for EV charging system practically, the transfer efficiency characteristics for the HTS wires should be investigated. In this study, we examined transfer characteristics with copper-stabilizer HTS antenna at 77 K and copper antenna at 77 K, respectively. The transfer distance is at 30 cm, and RF power of 370 kHz below 500 W is adopted. Moreover, in order to improve the transfer efficiency, the design considerations for the SUWPT system were described.