Electromagnetic-Thermal Design and Analysis of Liquid Nitrogen Immersed Aluminum Armature With NI HTS Field Windings

This paper presents an electromagnetic and thermal design methodology for a liquid-nitrogen (LN$_{2}$)-immersed aluminum armature with no-insulation high-temperature superconducting (NI-HTS) field windings. A three-dimensional finiteelement model is developed to optimize both the armature geometry and the NI-HTS coil configuration. The analysis evaluates key electromagnetic performance metrics, including torque density and electromagnetic coupling. Steady-state thermal analysis, incorporating LN$_{2}$convective cooling coefficients and the anisotropic thermal properties of epoxy-impregnated windings, predicts operating temperature distributions and establishes safe current density limits. Numerical case studies for an aluminum armature and NI-HTS coils submerged in LN$_{2}$show a torque output of 15N$\cdot$m at an armature current density of 20A/mm${}^{2}$(RMS), with a thermal limit of 3…