  The estimation of losses in high-temperature superconductors (HTS) is
fundamental during the design of superconducting devices since losses can
strongly influence the cooling system requirements and operating temperature.
Typically, 2D finite element analysis is used to calculate AC losses in HTS,
due to the lack of analytical solutions that can accurately represent complex
operating conditions such as AC transport current and AC external applied
magnetic field in coils. These 2D models are usually a representation of an
infinitely long arrangement. Therefore, they cannot be used to analyze end
effects and complex 3D configurations. In this publication, we use the T-A
homogenization in 3D for the analysis of superconducting coils. This allows
simulating complex geometries such as racetrack coils. We show that this
approach has lower computation time than the currently available 3D
homogenization of the H formulation. The approach is first validated against
measurements and 2D axisymmetric solutions. Then, it is used to estimate losses
and study the electromagnetic behavior of a racetrack coil.
