Study of the Influence of the Reluctance of a High- Temperature Superconductor on an Eddy-Current Axial Flux Superconducting Coupling

This article presents the influence of the reluctance of a novel hybrid superconducting coupling with axial flux. The coupling is made of the permanent magnets (PMs) in the primary and the copper and split superconductor with variable reluctance in the secondary. The study is made when the superconducting is in the vortex zone. The distribution of torque and magnetic field properties is examined and computed using a magnetic equivalent circuit model. Since the permeability and the conductivity vary according to the temperature and the magnetic field around the superconductor, the graph of the evolution of the eddy-current density is derived. By employing the curve fitting technique, we obtained the polynomial equation of the eddy-current density, then this equation allowed us to figure out the formula of the eddy-current density. By knowing the density of the eddy current, we were able to deduce the expressions of the bulk conductivity, then the London penetration depth, and the relative permeability of the superconductor. These expressions allowed us to determine how the superconductor's reluctance varies depending on the temperature. The force and output torque are calculated using a combination of Kirchhoff's law and Ampere's loop law, respectively, and also by considering the variation of the reluctance according to the temperature. In order to expand the coupling's operating margin, the performance is examined by utilizing a high-temperature superconductor with a temperature range of 77–130 K. The strong agreement between the torque simulation results and the outcomes of the proposed model's calculations demonstrates the accuracy of both results.