Bidirectional Marx DC-DC Converter for Offshore Wind Farm Application

The bidirectional DC-DC converter explained in this paper is based on the Marx principle, and is capable of achieving step-up and step-down voltage transformations at kV level and is able to handle MW level power transfers in both directions. The main features of this topology is the absence of a high frequency transformer, reduced weight, volume, and soft switching to reduce the switching losses. In the boost mode, five capacitors are charged in parallel and discharged in series to achieve the step-up action, and in the buck mode the converse action takes place. The operating principle is explained, and the steady-state analysis of the converter is given. Matlab/Simulink simulation of a 50MW converter, interfacing 6kV, and 30kV systems supports and validates the theoretical analysis, and enables positive supporting conclusions to be made.