Design and Characteristic Analysis of an Inductive Link for Wireless Current Charging of a HTS Magnet

Laboratory electromagnets are a type of scientific instrumentation widely used to study physical characteristics such as magneto-optical, magnetic hysteresis, and susceptibility properties. In laboratory electromagnets, it is important to generate a high field stably while also reducing the weight. This can generally be achieved by improving the magnetic properties of the ferromagnetic material used for the iron yoke or by increasing the operating current density of the excitation coil. High-temperature superconducting (HTS) coils can generate higher magnetic fields with smaller volumes compared to the copper coils used in conventional laboratory electromagnets due to their high current-carrying capacities. However, when excitation current in conventional HTS coils is generally charged using a power-driven mode, a high heat transfer load from the busbar occurs. The heat transfer load to the HTS coil deteriorates the operational efficiency and stability of the electromagnet system. To mitigate this problem, this paper proposes an inductive link for wireless current charging for laboratory HTS magnets. A magnetic coupler for the inductive link is also designed in consideration of the coupling coefficient, and a resonance circuit and rectifier circuit are designed using elements whose operational characteristics were verified in a cryogenic environment. Evaluating the feasibility of the proposed method is carried out via a finite element analysis combined with an electrical circuit analysis.