High temperature superconducting magnetic bearing (SMB) based on the mutual coupling between high temperature superconductor (HTS) bulks and permanent magnets (PM) exhibits excellent self-stability and is highly promising for use in rotating systems. To further improve its load capacity and stability, it is necessary to optimize the PM rotor. In this paper, we establish the three-dimensional thrust type bearing and journal type bearing models using the H-ϕ formulation combined with the moving mesh module, and the calculation result is compared with the experimental result to prove the accuracy of this calculation method. We optimize the original opposite polarity PM rotor and propose two Halbach arrangement optimization schemes in each bearing type, which can gather a larger magnetic flux density. For each type of bearing, we investigate the effects of the corresponding three different rotors on the levitation performance and relaxation characteristics of the bearing during the zero field cooled (ZFC) magnetization, and the electromagnetic transient distribution and temperature variation of the superconducting stator are presented in detail. The results show that in the thrust type bearing, the optimized scheme of the radial Halbach array leads to the most effective enhancement of the magnetic field on the rotor surface, and the maximum levitation force and maximum levitation force stiffness in the ZFC coupling process are 4 times and 2.3 times that of the original bearing, respectively. In the journal type bearing, the Halbach Array II optimization scheme most effectively enhances the magnetic field at the rotor surface. Under radial ZFC coupling, this optimization results in a 4.9 times increase in maximum radial levitation force and a 3 times increase in maximum force stiffness compared to the original bearing. This optimization scheme achieves a 5.5 times increase in axial levitation force in axial ZFC coupling. During the relaxation process of the two types of bearing, the optimized PM rotors cause more intense flux creep, resulting in more levitation force loss, but the higher force stiffness protects the stability of the bearings. The proximity of the optimized PM rotors intensifies the flux movement of the HTS bulks but only brings about a limited temperature rise, and the superconductor maintains a good low-temperature working environment during the coupling process. This study is expected to provide some reference for the optimal design of compact HTS flywheel energy storage systems (FESSs).
[1] Kexi Xu, Dongjie Wu, Y L. Jiao et al., “A fully superconducting bearing system for flywheel applications,” Superconductor Science and Technology, vol. 29, no. 6, 2016.
[2] H. H. Song, J. Zheng, M. X. Liu et al., “Optimization and design of the permanent magnet guideway with the high temperature superconductor,” Ieee Transactions on Applied Superconductivity, vol. 16, no. 2, pp. 1023-1026, Jun, 2006.
[3] Z. Deng, N. Qian, T. Che et al., “Comprehensive comparison of the levitation performance of bulk YBaCuO arrays above two different types of magnetic guideways,” Journal of Magnetism and Magnetic Materials, vol. 420, pp. 171-176, 2016.
[4] Z. Deng, J. Wang, J. Zheng et al., “High-efficiency and low-cost permanent magnet guideway consideration for high-Tcsuperconducting Maglev vehicle practical application,” Superconductor Science and Technology, vol. 21, no. 11, pp. 36-36, 2008.
[5] Z. Deng, J. Zheng, H. H. Song et al., “A new HTS/PMG maglev design using halbach array,” 2006 Bimw: 2006 Beijing International Materials Week, Pts 1-4, vol. 546-549, pp. 1941-+, 2007.
[6] Z. G. Deng, W. H. Zhang, J. Zheng et al., “A High-Temperature Superconducting Maglev Ring Test Line Developed in Chengdu, China,” Ieee Transactions on Applied Superconductivity, vol. 26, no. 6, pp. 1-8, Sep, 2016.
[7] E. S. Motta, D. H. N. Dias, G. G. Sotelo et al., “Optimization of a Linear Superconducting Levitation System,” Ieee Transactions on Applied Superconductivity, vol. 21, no. 5, pp. 3548-3554, Oct, 2011.
[8] M. Abdioglu, K. Ozturk, H. Gedikli et al., “Levitation and guidance force efficiencies of bulk YBCO for different permanent magnetic guideways,” Journal of Alloys and Compounds, vol. 630, pp. 260-265, 2015.
[9] Y. Y. Lu, and Q. H. Dang, “Magnetic Forces Investigation of Bulk HTS over Permanent Magnetic Guideway under Different Lateral Offset with 3D-Model Numerical Method,” Advances in Materials Science and Engineering, vol. 2012, no. 2012, 2012.
[10] C. Q. Ye, G. T. Ma, K. Liu et al., “Intelligent Optimization of an HTS Maglev System With Translational Symmetry,” Ieee Transactions on Applied Superconductivity, vol. 26, no. 4, pp. 1-5, Jun, 2016.
[11] Z. G. Deng, W. F. Zhang, Y. Chen et al., “Optimization study of the Halbach permanent magnetic guideway for high temperature superconducting magnetic levitation,” Superconductor Science & Technology, vol. 33, no. 3, pp. 034009 (8pp), Mar, 2020.
[12] J. R. Hull, and A. Cansiz, “Vertical and lateral forces between a permanent magnet and a high-temperature superconductor,” Journal of Applied Physics, vol. 86, no. 11, pp. 6396-6404, 1999.
[13] J. Li, H. Li, J. Zheng et al., “Nonlinear vibration behaviors of high-Tc superconducting bulks in an applied permanent magnetic array field,” Journal of Applied Physics, vol. 121, no. 24, pp. 778-783, 2017.
This work was supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDB25000000, National Natural Science Foundation (52172271)