Electromagnetic-Thermal Analysis of an HTS Linear Motor for High-Dynamic Applications

This article presents and applies an electromagnetic-thermal model to design a double-sided coreless, conduction-cooled high temperature-superconductor (HTS) linear motor for a high-dynamic motion application, and assesses the thermal stability of the superconducting coils for continuous long term operation. The analysed motor topology contains stationary DC operated superconducting coils and conventional three-phase AC commutated mover-coils. The stator is a vacuum chamber which houses a cryogenic assembly containing the superconducting coils. The framework utilizes three computationally efficient models: a two-dimensional finite-element-method (2D FEM) model to evaluate the feasibility of superconducting coils under static conditions, a semi-analytical model to compute the motor thrust and eddy-current losses in electrically conductive structures of the cryostat during dynamic motion, and a 2D FEM full-scale model of the linear motor for overall loss calculation in the stator. The motor design, optimized for minimum volume, and an operating temperature of 20 K, produces a peak magnetic flux density of 5.43 T in the air gap in static conditions which results in a force density of 4700 kN/m(3). Results show that steady-state temperature in the superconducting coils does not exceed 25 K. As such, the dynamic losses do not result in quenching of superconducting coils. This paper shows that a reliable operation of superconducting coils during high-dynamic motion condition is feasible.