Experimental study of a high-temperature superconducting induction/synchronous motor with REBCO bulk bars for transportation applications

Abstract

Lightweight and highly efficient high-temperature superconducting (HTS) rotating electric machines show great potential for transportation applications. An advantage of RE-Ba-Cu-O (REBCO, where RE=rare earth) bulk superconductors over stacked HTS tapes is their ability to carry larger and more homogenous currents. This study is the first in which an HTS induction/synchronous motor (HTS-ISM) with Gd-Ba-Cu-O (GdBCO) bulk superconductors has been successfully designed, fabricated, and tested. Our fabricated prototype featured a squirrel-cage rotor wound with 44 GdBCO bulk bars that were embedded in the rotor iron and connected at both ends using Y-Ba-Cu-O (YBCO) tapes to form a short circuit. First, the critical current of the bulk sample was investigated under a magnetic field perpendicular to its top surface at 77 K. Subsequently, no-load and load tests were performed in liquid nitrogen at different frequencies to verify the performance of the prototype. Finally, we thoroughly analyzed the differences between the proposed HTS-ISM that utilizes GdBCO bulk bars and developed HTS-ISMs that utilize a few turns of YBCO or Bi-Sr-Ca-Cu-O (BSCCO) tapes per bar.