IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 24, NO. 3, JUNE 2014 3600405 Lateral Displacement Influence on the Levitation Force of YBCO Coated Conductor Linear Bearings Felipe Sass, Daniel Henrique Nogueira Dias, Guilherme Gonçalves Sotelo, and Rubens de Andrade, Jr. Abstract—Superconducting coated conductors have been used for several large-scale applications. One potential application for YBCO second-generation (2G) wire is the development of super- conducting magnetic bearings (SMB). The main advantages of 2G wires are large scale production, high critical current density val- ues, lower manufacturing cost than first generation, and superior performance under high magnetic fields. This work proposes a study of a linear SMB using 2G wires as a passive levitator for MagLev vehicles. The 2G block is conceived to replace the YBCO bulk in the MagLev’s SMB prototype, which is being built at Federal University of Rio de Janeiro. In this context, a supercon- ducting block using stacked 2G wires was built to evaluate the behavior of this SMB. The forces between the 2G block and a per- manent magnet were measured and compared with the results for an YBCO bulk with nearly the same dimensions. The experimental rig used for this work allows vertical and lateral displacements and a load cell is used to evaluate the SMB levitation force decay due to the lateral movement. The 2G block has presented lower force levels than ordinary YBCO bulks, but it presents potential to be applied in a SMB application. Index Terms—Coated conductors, second generation (2G) HTS wire, superconducting magnetic bearing (SMB). I. I NTRODUCTION T HE Superconducting Magnetic Bearing (SMB) has been extensively studied in the literature. Linear or rotational SMB can be designed and applied in the development of MagLev vehicles [1]–[3] and rotational devices [4]–[6]. The SMB has its operating principles based on the repulsive force between superconductor bulks and the magnetic field of perma- nent magnets. The production of a set of YBCO bulks for SMB takes about one week, in a complex and expensive process. For this reason it is difficult to upscale its production. The development of devices for commercial purposes motivated our team to investigate new possibilities for SMB, allowing the replacement of YBCO bulk. Recently, manufacturers are able to produce high quality second generation (2G) superconductor wires hundreds of meters long [7], [8]. This fact has given new perspectives for several engineering applications, such as: power system devices [9], power transmission and distribution cables [10], fault current limiters [11], electric machines [12], Manuscript received July 15, 2013; accepted October 29, 2013. Date of publication November 7, 2013; date of current version November 21, 2013. This work was supported in part by the Brazilian agencies CAPES, CNPq, FAPERJ, BNDES, and FOPESQ/UFF. F. Sass and R. de Andrade, Jr. are with Federal University of Rio de Janeiro, 21941-901 Rio de Janeiro-RJ, Brazil (e-mail: felipesass@ufrj.br; rubens.andrade@ufrj.br). D. H. N. Dias and G. G. Sotelo are with the Fluminense Federal University, 24220-008 Niteröi-RJ, Brazil (e-mail: dhndias@id.uff.br; gsotelo@id.uff.br). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TASC.2013.2289300 Fig. 1. Illustration of the maglev Cobra: (a) vehicle and (b) cryostat (unit: mm). high field magnets coils [13], and others. In this context, the present work studies the construction of a new type of bearing using several pieces of coated conductors stacked. To verify the feasibility of 2G wires for the SMB appli- cations, the permanent magnet guideway (PMG) from the MagLev Cobra [1] project was used as source of external magnetic field. This paper presents an investigation of this SMB system considering the levitation force decay due to lateral movements. During experiments, vertical and lateral displace- ments of the PMG in relation to the superconductor were made. The results show the potential of the 2G superconductor wires for SMB applications, especially considering the upscaling production of superconducting bearings, but its feasibility still depends on the cost reduction of the YBCO wires. II. YBCO-COATED CONDUCTOR LINEAR BEARINGS To start the mass production of Maglev vehicles, thousands of YBCO melt-textured bulks would be necessary. For example, Fig. 1 shows an illustration of the Maglev Cobra vehicle that is being build at Federal University of Rio de Janeiro with its 24 cryostats, each one with 24 YBCO bulks (total of 576 bulks). There are some possibilities available to replace the bulk by coated conductors as passive levitators: coils with wires terminals short circuited [14], one looping coil made by cutting 1051-8223 © 2013 IEEE