High voltage cascaded step-up DC-DC Marx converter for offshore wind energy systems

This paper presents an improved cascaded DC-DC resonant converter for offshore windfarms. The improvements are reduced losses and the number of components. The topology is based on the Marx principle where charged capacitors are charged in parallel and discharged in series to achieve the voltage transformation. The four inductors of the converter are designed to resonate with the capacitors to create resonance forcing current zeros to enable zero current switching thereby reducing switching losses. The operating principles and design considerations of the proposed converter are discussed and the design equations are presented. In order to evaluate the operation of 50 MW converter aimed at connecting a 30 kV DC Busbar in a wind power collection system to a 360 kV high voltage DC bus for transmission to the onshore grid was simulated and the results are presented.