Design Considerations for a 50 kW Dual Bridge Series Resonant DC/DC Converter with Wide-Input Voltage Range for Solid-State Transformers

Solid-State transformers (SST) consist of isolated bidirectional DC-DC Converters as a link between the Active Front End (AFE) and the DC-AC converter to adjust the voltage across the two DC links. Dual-Bridge Series Resonant Converter (SRCDAB) is one of the promising topologies for such applications. In this paper, the design methodology for SRC-DAB is explained for wide-input voltage range which can be used in universal voltage SSTs across global LV grids. The converter operates using Single Phase Shift (SPS) modulation scheme with a constant and unique switching frequency for different grid connections. The practical methodology of selecting the switching frequency, transformer turns ratio and resonant tank parameters for minimum peak semiconductor losses for the complete input voltage range has been described in this paper. The converter is designed to provide constant power output of 50 kW at 750 V for an input voltage range of 300-800 V. An experimental 10 kW prototype is shown.