Improvement of the Variable Speed Controllability of a 20 kW Class High-Temperature Superconducting Induction/Synchronous Motor at No-Load Condition

We have carried out the research and development of a high-temperature superconducting (HTS) motor, which has been expected for the application of the next-generation transportation equipment, e.g., train, bus, etc. Our motor is the so-called HTS induction/synchronous motor (HTS-ISM). In this paper, we carry out the so-called JC08 rotation test at no-load condition for the fabricated 20 kW class motor, and investigate the tracking performance of it. It is shown that the operating performances, i.e., starting characteristics and rotational vibration at higher speed, are possibly improved by the simple control method such conventional ones as the torque boost technique and the field weakening control, even though the HTS rotor windings own nonlinear current transport characteristics. The results of this work suggest that the HTS-ISM in no-load conditions can be controlled by a simple standard control strategy.