Electrothermal Characteristics of YBCO Bulk Magnets Deep in LN2: A Preliminary Analysis for Its Use as Excitation System of Low-Speed Synchronous Generators

This paper introduces a preliminary analysis concerning the use of YBCO bulk magnets when operating in the magnetic environment of low-speed synchronous generators. A coupled electrothermal Comsol model of bulk YBCOs is first developed, tested, and experimentally verified. Joule losses in the HTS magnet are then studied when under ac homogeneous standing magnetic field wave with frequencies and amplitude ranges that are usually found on those generators. The YBCO capability in maintaining its magnetization level when subjected to those conditions was also analyzed since the objective is to replace the permanent magnets currently in use to increase up to +30% the air-gap field.