Design of a Three-Phase Series Resonant Converter for Offshore DC Grids

Offshore wind farms for the generation of electrical power is an ongoing discussion for several years. A major challenge today is to reduce the cost for the electrification of these large scale wind farms. A possible solution is to use a DC collector grid instead of conventional AC systems. However, to realize this, high-power DC/DC converters are needed to transform the voltages within the grid. The Series Resonant Converter, which will be discussed in this paper offers a possible solution that is efficient and cost effective. First, the fundamentals on three-phase SRC systems are discussed, before the soft-switching characteristics of high-power semiconductors are discussed and measurement results are presented. Next, a modified topology of the SRC is presented allowing an asymmetric bi-directional power flow which is essential for the usage in offshore wind farms. Finally, the total efficiency of converter will be determined tor different frequencies.