Numerical Investigation of AC Loss in HTS Bulks Subjected to Rotating Magnetic Fields

High-temperature superconductor (HTS) bulks have shown very promising potential for industrial applications due to their highly attractive superconducting characteristics. The practical application, however, has been handicapped by the AC losses. In rotating electrical machines, the magnetic field is a combination of alternating and rotating fields. All the AC loss studies presented in the literature so far have only focused on the alternating AC loss due to the unavailability of experimental techniques and analytical models. This paper presents a numerical investigation of AC loss by using the H-formulation under various two-dimensional rotating magnetizations with the magnetic flux density vectors rotating in clockwise and anti-clockwise directions in the XOY, XOZ, and YOZ planes. The modeling results show that the rotational AC loss of HTS bulk material is significantly higher than the alternating AC loss.