Operational Mode Analysis of the Isolated Three-Phase DC/DC Converter

This paper presents a comprehensive analysis of the operational modes of the unidirectional DC/DC converter, featuring a medium frequency Y-Y transformer and output filter inductor (3-ph DC/DC). All modes of operation are presented for the first time for this converter and mechanisms and conditions governing the transitions between the modes are discussed. The converter steady-state model is given. Steady-state operation is studied in detail and trade-offs between operational modes are identified from the perspective of input/output voltage controllability, device current stress, output current ripple and soft switching range implications, providing the necessary basis for the converter design. To validate the theoretical findings, a small-scale prototype of the converter was commissioned and used for experimental tests.