  High temperature superconducting (HTS) synchronous motors can offer
significant weight and size reductions, as well as improved efficiency, over
conventional copper-wound machines due to the higher current density of high
temperature superconducting (HTS) materials. In order to optimise the design
parameters and performance of such a machine, this paper proposes a basic
physical model of an air-cored HTS synchronous motor with a copper armature
winding and HTS field winding. An analytical method for the field analysis in
the synchronous motor is then presented, followed by a numerical finite element
analysis (FEA) model to verify the analytical solution. The model is utilised
to study the influence of the geometry of the HTS coils on the magnetic field
at the armature winding, and geometrical parameter optimisation is carried out
using this theoretical model to obtain a more sinusoidal magnetic field at the
armature, which has a major influence on the performance of the motor.
