Feasible study of wireless power charging system for EDS-based superconducting magnetic levitation train using HTS receiver

Recently, the wireless power transfer (WPT) systems have started to be applied to the wireless charging for electrical vehicles and trains because of their advantages compared with the wired counterparts, such as convenience, safety, and fearless transmission of power. However, it has obstacles to commercialize to large power deliver and efficiency in WPT technology. This paper presents the feasibility of technical fusion between wireless power transfer (WPT) system and superconducting magnet technology to enable to charge large power into very low temperature circumstance of superconducting magnet for high speed magnetic levitation (MAGLEV) train without any connector or wire. The superconducting magnet in high speed MAGLEV train system maintains keeps stronger magnetic field that plays a role to sustain stable levitation gap. Generally, the superconducting magnet has been supplied by conventional electric power persistently to keep fixed levitation gap and low irregularity tolerance. However, a large thermal loss is indispensably caused by power transfer wires. Fortunately, since superconducting wires have a higher Q-value intrinsically, transfer selectivity and distance between antenna and receiver coils can be improved easily. Thus, the superconducting receiver (Rx) coil for superconducting magnet can be expected as a reasonable option to deliver large power with high efficiency. In this paper, we designed and investigated wireless power transfer system for the wireless power charging system for superconducting Maglev (WPC4SM) using high temperature superconducting (HTS) receiver. To confirm the capacity of HTS Rx coil, we compared with operating efficiency using normal conducting Rx coil. As a result of investigation, the transfer efficiency with HTS receiver could be successfully improved over 30 % compared with copper receiver at laboratory scale with a purpose built test stand.