Optimization of a Horizontal Axis HTS ZFC Levitation Bearing Using Genetic Decision Algorithms Over Finite Element Results

Abstract

In this article, a multiobjective optimization is done to minimize the cost and volume of a horizontal axis high-temperature superconductors (HTS) levitation bearing. The optimization is done using 3-D finite-element analysis (FEA) and an equivalent magnetic permeability model for HTS bulks depending on the applied magnetic field. The use of this equivalent permeability model rather than the HTS magnetization Kim's model is required to perform the optimization process in a feasible time. The computation time for 3-D FEA with Kim's HTS model is 43.6 h and with the equivalent permeability model is 2.2 min. The equivalent permeability model is described and calibrated using experimental results from a previously developed D5 levitation bearing and is then used in the optimization process. From the cost optimization, results show that it is possible to reduce by 45.9% the cost of the levitation bearing by reducing the HTS volume by 55.4% and increasing the permanent magnet's (PM's) volume by 69.6%, while maintaining the same net lifting forces. From the volume optimization, it was possible to reduce both HTS and PM's volume by 16.2% and 22.4%, respectively, and to reduce the overall levitation bearing cost by 16.6%. From the optimization, it was verified that the solution from the cost optimization provided an increase of stability (guidance forces).