Levitation Force Maximization in HTS Magnetic Bearings Formulated by a Semianalytical Approach

High-speed rotatory electromechanical devices can be practically implemented using magnetic bearings that provide a contactless operation. Besides the contactless operation, high-temperature superconducting (HTS) bearings possess an exclusive feature, i.e., self-stability. This characteristic removes requiring any control schemes and consequently an easier implementation and lower costs would be expected. This paper deals with presentation of an optimal rotor configuration in radial-type HTS bearings. A semianalytical approach called Adomian decomposition method is used to efficiently solve the governing equations of HTS bearings deduced from the H-formulation combined with the E-J power law. Control variables of the optimization process include rotor dimensions as well as magnetization direction of permanent magnets. Optimization is carried out using a powerful approach called differential evolution with maximization of levitation force around the equilibrium position as its objective function. In order to verify the proposed approach, a two-dimensional axisymmetric finite element method is also implemented.