Development and fundamental study on a superconducting induction/synchronous motor incorporated with MgB2 cage windings

In this paper, a fundamental study of the rotating characteristics of a induction/synchronous motor by use of superconducting MgB2 cage windings is carried out based on analysis and experiment. Current transport properties of the produced monofilamentary MgB2 wires are firstly characterized, and then utilized for the determination of the current carrying capacity of the rotor bars. Then, the motor model is designed and fabricated with the aid of conventional (copper) stator windings. We successfully observe the synchronous rotation of the fabricated motor at a rotation speed range from 300 to 1800 rpm. We can also realize an almost constant torque versus speed curve, and this characteristic is explained from the steep take-off of the electric field versus the current density curve, based on the nonlinear electrical equivalent circuit. These results are promising for the practical applications of a high efficiency motor for a liquid hydrogen circulation pump.