Optimal Design of Resonance Circuit Topology for a Wireless Power Transmission System Using HTS Coils

We have been investigating a wireless power transmission (WPT) system using high-temperature superconducting (HTS) coils for stopped railway vehicles at a station. On the other hand, the design guidelines of the resonance circuit topologies (SS, SP, PS, and PP topologies) suitable for the WPT system using the HTS coils have not been sufficiently established. Therefore, it is necessary to clarify the resonance circuit topology to minimize AC losses in HTS coils. In this study, we analyzed the power transmission characteristics of different resonance circuit topologies in the WPT system using HTS coils by finite element method calculation. Also, we investigated the design guidelines of the resonance circuit topologies suitable for the WPT system using the HTS coils for the railway vehicles. As a results, the WPT systems using the HTS coils were capable of high-efficiency power transmission when the primary and secondary coil voltages were at maximum voltage under the constraint condition of each system. Furthermore, the transmission efficiency between coils of the SS topology was the largest compared to the other topologies. Also, the transmission efficiency of the SP and PS topologies was slightly lower than that of the SS topology. From the above, it was found that the SS topology is suitable for WPT systems using the HTS coils requiring a constant current to the load resistance, while the SP or PS topologies are suitable for WPT systems requiring a constant voltage to the load resistance.