As the offshore wind industry moves further offshore HVDC transmission is becoming increasingly popular. HVDC transformer substations are not optimised for offshore industry however, increasing costs and reducing redundancy. A modular HVDC transformer located within each wind turbine nacelle could mitigate these problems however, careful design is required to minimise losses. For example the converter topology will influence the semi-conductor and magnetic transformer losses. In this paper several transformer configurations comprising combinations of the H-Bridge and Modular Multilevel Converter topologies are modelled in the Matlab/Simulink environment. The configurations are evaluated for use in a medium frequency HVDC transformer based on their contribution to total losses, their stability and range of real and reactive power control.