Development of Stator Windings for Fully Superconducting Motor With $\hbox {MgB}_{2}$ Wires

Stator windings for a superconducting motor with MgB₂ wires are fabricated and tested. The stator windings are composed of 12 element coils in the form of a racetrack, and located in iron core slots to generate a rotating magnetic field of three phases and four poles. Preliminary estimations by means of numerical calculations with a finite element method indicate that the magnetic-flux distribution in a gap between the stator and rotor cores contains relatively significant components of fifth and seventh harmonics compared with a fundamental component. An MgB₂ rotor prepared in the previous work can be rotated at a synchronous speed successfully by energizing the fabricated stator windings with a pulse width modulation inverter and compensating for the higher harmonics with a torque boost voltage.