  Numerical models are powerful tools to predict the electromagnetic behavior
of superconductors. In recent years, a variety of models have been successfully
developed to simulate high-temperature-superconducting (HTS) coated conductor
tapes. While the models work well for the simulation of individual tapes or
relatively small assemblies, their direct applicability to devices involving
hundreds or thousands of tapes, as for example coils used in electrical
machines, is questionable. Indeed the simulation time and memory requirement
can quickly become prohibitive. In this article, we develop and compare two
different models for simulating realistic HTS devices composed of a large
number of tapes: 1) the homogenized model simulates the coil using an
equivalent anisotropic homogeneous bulk with specifically developed current
constraints to account for the fact that each turn carries the same current; 2)
the multi-scale model parallelizes and reduces the computational problem by
simulating only several individual tapes at significant positions of the coil's
cross-section using appropriate boundary conditions to account for the field
generated by the neighboring turns. Both methods are used to simulate a coil
made of 2000 tapes, and compared against the widely used H-formulation finite
element model that includes all the tapes. Both approaches allow speeding-up
simulations of large number of HTS tapes by 1-3 orders of magnitudes, while
keeping a good accuracy of the results. Such models could be used to design and
optimize large-scale HTS devices.
