Power Transmission Characteristics of the Wireless Power Transmission System Using Multiple HTS Coils and Copper Coils

Recently, large-capacity wireless power transmission (WPT) systems of over 500 kW are required for the rapid charging of batteries in electric vehicles (EVs). Therefore, we have been investigating a WPT system for EVs using a high-temperature superconducting (HTS) coil as the ground-side coil. In this study, we proposed the WPT system using multiple HTS and copper coils with a coil arrangement designed to minimize the cross-coupling between coils connected in parallel. Moreover, we investigated the power transmission characteristics of the proposed WPT system with respect to the number of coils and the operating temperature of the HTS coils. As a result, the receiving power of the proposed WPT system increased with an increase in the number of coils connected in parallel and with a decrease in the operating temperature of the HTS coils. Specifically, the receiving power exceeded the target of 500 kW in the 3 to 3 arrangement with three HTS coils and three copper coils at 40 K, and the 1 to 3 arrangement with one HTS coil and three copper coils at 40 K.