Effectiveness of REBCO Trapezoidal Armature Coils Used in Superconducting Induction Motors

Armature coils that use REBa2Cu3Oy (REBCO) wires are typically racetrack shaped owing to the tape shape of the wires. It is difficult to improve the motor output in armature windings composed of racetrack coils. Previously, we proposed trapezoidal-shaped REBCO coils for armature windings. In this study, we perform electromagnetic simulations of two types of induction motors with armature windings, one composed of trapezoidal coils and the other of racetrack coils. Subsequently, we show that the induction motor using trapezoidal coils exhibit a higher output than that using racetrack coils. Moreover, we present the fabrication of six trapezoidal coils for use in the armature winding and present the current-voltage (I - V) characteristics of the coils to determine the current flow. The results show that a current of 80 A or higher could flow in all the coils. Finally, we present the results from a load test of an induction motor that incorporates the trapezoidal coils for the armature winding and the corresponding torque slip characteristics. The analysis and load test results are comparable, thus experimentally demonstrating the effectiveness of using trapezoidal coils for armature windings to increase the motor output.