The high-Tc superconducting (HTS) dynamo is a promising device that can inject large DC supercurrents into a closed superconducting circuit. It could be used, for example, to energise rotor windings in superconducting rotating machines without the need for connection to a power supply via current leads. A number of different numerical models have now been developed as useful and cost-efficient tools to further examine and explain experimental results, as well as optimise and improve flux pump design. To adequately compare the different modelling tools available, we propose a new benchmark numerical model for the HTS modelling community: the HTS dynamo. In this work, this benchmark problem is implemented using several different methods: (1) coupled H-A formulation, (2) H-formulation + shell current, (3) segregated H-formulation, (4) Minimum Electromagnetic Entropy Production (MEMEP), (5) coupled T-A formulation, (6) integral equation and (7) volume integral equation-based equivalent circuit. These different techniques are used to solve the benchmark problem and compared in terms of computational requirements, ease of use and the solutions obtained with reference to each other, as well as experimental measurements.