Characteristics of axial-type HTS motor under different temperature conditions

We tested an axial-type Bi-2223 bulk motor under different magnetic field and temperature conditions. Distributed armature windings with a pole number of four were used in order to compensate for the harmonic components in the air-gap magnetic flux density. The temperature was varied by evacuating the metal cryostat with a rotary vacuum pump. The fabricated motor demonstrated hysteresis characteristics when the temperature of the system was decreased and the magnetomotive force was adjusted to appropriate values. Then, synchronous speed at no-load condition was fulfilled. On the other hand, slip of rotational speed as well as inductive torque was induced when temperature and magnetic conditions were not satisfied. These results can be explained based on the pinning properties and AC loss inside the bulk rotor.