  The high-Tc superconducting (HTS) dynamo is a promising device that can
inject large DC supercurrents into a closed superconducting circuit. This is
particularly attractive to energise HTS coils in NMR/MRI magnets and
superconducting rotating machines without the need for connection to a power
supply via current leads. It is only very recently that quantitatively
accurate, predictive models have been developed which are capable of analysing
HTS dynamos and explain their underlying physical mechanism. In this work, we
propose to use the HTS dynamo as a new benchmark problem for the HTS modelling
community. The benchmark geometry consists of a permanent magnet rotating past
a stationary HTS coated-conductor wire in the open-circuit configuration,
assuming for simplicity the 2D (infinitely long) case. Despite this geometric
simplicity the solution is complex, comprising time-varying
spatially-inhomogeneous currents and fields throughout the superconducting
volume. In this work, this benchmark problem has been implemented using several
different methods, including H-formulation-based methods, coupled H-A and T-A
formulations, the Minimum Electromagnetic Entropy Production method, and
integral equation and volume integral equation-based equivalent circuit
methods. Each of these approaches show excellent qualitative and quantitative
agreement for the open-circuit equivalent instantaneous voltage and the
cumulative time-averaged equivalent voltage, as well as the current density and
electric field distributions within the HTS wire at key positions during the
magnet transit. A critical analysis and comparison of each of the modelling
frameworks is presented, based on the following key metrics: number of mesh
elements in the HTS wire, total number of mesh elements in the model, number of
degrees of freedom (DOFs), tolerance settings and the approximate time taken
per cycle for each model.
