Design Considerations of Superconducting Armature Winding in PM-Excited AC Machines

Assumptions related to the design of AC machines with permanent magnet excitation and armature winding made of high-temperature superconductors (HTS) and related FEM analysis are presented in the paper. The influence of machine design parameters and coefficients on the design process are being considered. The considerations are carried out in order to reduce the negative effect of magnetic field on HTS winding. The highest possible utilization of HTS wire is extremely important both from economic and engineering point of view. The considerations are limited to low power machines with fractional-slot winding up to 1 kW and cooled with liquid nitrogen (77 K). The distribution of magnetic field in slots is analyzed in details and its influence on the value of the critical current in coils calculated using FEM.