Magnetic Shielding Design and Performance Improvement of HTS Coil for Single HTS-Excitation Claw-Pole Field-Modulation Machine

In the single high-temperature-superconducting (HTS)-excitation claw-pole field-modulation (SHTS-CPFM) machine investigated in this article, the armature reaction field that penetrates the HTS-excitation coil has a nonnegligible amplitude, which would lead to the reduction of critical current I-c, thus decreasing the electromagnetic performance of the SHTS-CPFM machine. Therefore, the purpose of this article is to propose and design a compound magnetic shielding, which consists of segmented flux diverter (FD) and superconducting shielding layer. The innovation is the proposal of segmented FD having a smaller size and stronger flux diversion ability compared with the unsegmented FD, and introducing the YBCO-tape shielding layer instead of traditional metal shielding layer to achieve improved ac flux shielding due to the full use of the Meissner effect. The results show that by introducing the proposed CMS, the critical current I-c and the field current I-f of the HTS-excitation coil in the analyzed SHTS-CPFM machine can be increased by 14.8% and 12%, respectively, thus achieving a 6.4% improvement in machine torque capacity.