Performance evaluation of a low-speed single-side HTS linear induction motor used for subway system

Due to the critical characteristics and the magnetic flux pinning phenomenon of the high-temperature superconducting (HTS) material, the electromagnetic calculation for the HTS motor is more complicated than for conventional motors. In this paper, the equivalent electrical conductivity and the equivalent magnetic permeability are proposed to represent the critical characteristics and the magnetic flux pinning phenomenon, respectively. Considering the low-speed single-sided HTS linear induction motor as an example, the 2-D mathematical model is established and its boundary conditions are given. The model is solved using the time-step finite-element method. The flux density distributions and the performance parameters, such as thrust, vertical force, eddy-current loss, efficiency, power factor, and so on, are obtained. In addition, the magnetic flux density around the HTS windings is also calculated to evaluate the influence of the leakage magnetic flux on the critical current. Finally, the experiment is carried out to validate the accuracy of the established model.