Design, Fabrication, and Testing of a YBCO Racetrack Coil for an HTS Synchronous Motor With HTS Flux Pump

An experimental platform of high temperature superconducting (HTS) synchronous motor with HTS flux pump has been designed and under construction. The HTS flux pump as an exciter eliminates thermal load from the metal current leads, which will reduce the cryogenic volume and improve the efficiency of the HTS machine. A finite element model (FEM) using T-A formulation was developed to analyze the electromagnetic characteristics of a double-pancake (DP) racetrack coil. The no-insulation (NI) racetrack coil wound by YBCO tapes was fabricated with a winding machine in our lab. We proposed a novel mechanical structure to avoid the impregnation of epoxy resin and make the coil more reliable. The turn-to-turn pressure of the racetrack coil can be changed by driving the screws on the straight section. Besides, we manufactured a rotating HTS flux pump as a DC power supply to charge the racetrack coil without contact. The self-field critical current test with a direct current (DC) power supply and the charging experiment with the HTS flux pump of the constructed YBCO racetrack coil were performed at 77 K.