Performance Comparison and Applicability Analysis of Different Armature Structures for a Small-Scale HTS Linear Synchronous Motor

High-temperature superconducting (HTS) coils could bear larger current density and produce higher magnetic field compared to permanent magnets. An HTS linear synchronous motor (LSM) with its secondary excitation system made of HTS coils can provide larger thrust force but unavoidable larger normal force. This paper focuses on the analysis and comparison of different armature structures in an HTS LSM to improve the magnetic flux waveform quality, decrease the normal force, and simultaneously maintain the thrust force. Five alternative armature structures are proposed and investigated, i.e., coreless double layer lap winding (DLLW), yokeless DLLW, coreless and yokeless DLLW, and flat winding with and without iron yoke. Three dimensional models of HTS LSMs are built and verified to compare the magnetic field and force performances of various armature structures using the finite element method. Results indicate that armatures without iron components perform better. Furthermore, the yokeless flat winding is recommended for its 81% reduction of magnetic flux harmonic component and 52% increase of thrust force compared with DLLW.