Quantitative characterization of nonlinear impedance and load characteristic of 50-kW-class fully superconducting induction/synchronous motor

Abstract

This paper reports an optimal technique to design a fully superconducting motor. A 50-kW-class fully superconducting induction/synchronous motor with both rotor and stator windings was fabricated from bismuth–strontium–calcium–copper-oxide (BSCCO) tapes and quantitatively characterized. The toroidal structure was adopted for the stator windings in order to increase their critical current in the iron core, and a squirrel-cage structure was used for the rotor windings. The three-phase AC loss was measured in atmospheric liquid nitrogen (77 K), and characterized as a function of the stator current and its frequency. Nonlinear self-inductance as well as mutual- inductance of the silicon steel core was estimated based on experimental and analytical methods. These nonlinear parameters were introduced into the voltage equations and then coupled with the equation of motion. The measured load characteristics were quantitatively reproduced despite complex nonlinear parameters.