High Temperature Superconducting Motor Power Density Improvements

Abstract

The use of high temperature superconducting (HTS) wire technology enables magnetic shear stress improvements in rotating machinery as high current densities can be achieved. The use of HTS wire, however, requires a large effective magnetic gap due to the use of full air-gap style stator windings as well as thermal insulation and electro-magnetic shielding to maintain HTS rotor coil operating temperatures within required limits. Due to these large magnetic gaps, HTS machines require large pole pitches to maximize the flux that links stator coils. Large pole pitches result in low pole numbers, which increase stator core and support structure weight. The use of a partial air-gap stator winding (CW-EMD patent pending) in an HTS motor effectively reduces the magnetic gap, which results in increased flux linkage with stator conductors. Reductions in the effective magnetic gap allow for the selection of smaller pole pitches and thus weight savings.