Operation and Performance of DC-DC Converter Using Multiple Cascaded Choppers for Future DC Power Grids

This paper proposes an isolated dc-dc converter suitable for the application to future dc power grids and energy storage station. The dc-dc converter is based on the conventional three-phase dual-active-bridge (TP-DAB) converter where a three-phase Yn-Y transformer with a three-limb core and auxiliary converters based on multiple cascaded bidirectional choppers are connected to the primary side of the transformer. Unlike the TP-DAB converter that suffers from large converter current because of the so-called reactive current, the proposed converter can reduce RMS and peak currents in a wide range of operating conditions. The operating principles and control method of the proposed are introduced in this paper, followed by the comparison of the TP-DAB converter with the proposed converter in terms of RMS and peak currents. The feasibility of the proposed converter is verified using a 150 V, 2.5 kW downscaled prototype.