Modeling and Analysis of HTS Linear Motors in High-Dynamic Applications

In this article, high-temperature superconducting (HTS) linear motors are modeled and analyzed for a high-dynamic application requiring a periodic, to-and-fro motion with substantial acceleration. Two topologies of a coreless double-sided HTS linear motor (HLM) are investigated: moving magnet motor (MMM) – a set of three-phase AC commutated HTS coils in the stator with permanent magnets in the mover, and moving coil motor (MCM) – a set of DC operated HTS coils in the stator with three-phase AC commutated normal coils in the mover. A two-step design process is adopted where transport current losses are used to determine feasible HTS coils to operate between 20 and 60 K, subject to requirements on input power for the cryogenic cooling system. Using the homogenized T-A formulation, a computationally fast 2D finite element method (FEM) model of the motor is developed to compute these losses. Additionally, a semi-analytical tool calculates the force produced by the motor. The MCMs with feasible HTS coils are then optimized to minimum volume. An MMM with the same force density is designed from the optimum MCM. The optimized motors are further analyzed using FEM for losses during high-dynamic motion. Results show that an MCM topology can reduce the motor volume by at least a factor of 10 when compared to conventional permanent magnet linear motors. The MCM delivers the required force in the same volume with significantly lower losses than an MMM.