T-A Formulation to Model Electrical Machines with HTS Coated Conductor Coils

Abstract

Modelling high temperature superconductor (HTS) motors remains challenging mainly due to the high aspect ratio of these conductors but also because of the properties of the magnetic materials. This paper presents a 2D time dependent model to assess the AC losses of superconducting motors based on the new T-A formulation, which by using Finite Element Methods (FEM), allows its implementation in commercial software. The T-A formulation computes the magnetic flux density with different Maxwell's equations depending on the areas of the motor and makes it possible to use the thin strip approximation i.e. the HTS tapes are modelled as infinitely thin lines. The model is then expected to tackle the high aspect ratio of the HTS as well as decreasing both the mesh complexity and the computing time. The first objective of the paper is to validate the method in 2D by evaluating the AC losses of a specific synchronous motor called SUTOR; the computed results are compared with good agreements to those assessed with the MEMEP method, already validated. In a second part, the same losses are computed, taking into account the anisotropy of Jc with the implementation of a data set based on experimentally measured Ic at 65 K and 77 K.