Parallel/series connection of self-sustained oscillating series-parallel resonant converters

In this paper, a new interconnection concept of two (or more) series-parallel resonant converter suitable for parallel/series connected inputs is proposed. With this connection method operation at a wide range of operating voltages and good semiconductor utilisation is enabled. Furthermore, the balance of the two resonant converter input voltages in case of a series connection is investigated and a method for improving the voltage balancing is presented. The proposed concept is verified by measurement results and the design of the converter/integrated transformer is discussed in detail.