Surge snubber design for high power-density DC-DC converters in HVDC power distribution systems

In an isolated DC-DC converter utilized in the HVDC power distribution system, a large surge voltage occurs across the secondary-side diodes due to the transformer´s leakage inductance, and then the diodes with a large withstand voltage are required. However, those diodes cause a lot of power loss. In this paper, a simple surge snubber with prominent surge suppression capability is examined, and the surge-voltage evaluation through the analysis using the high-frequency equivalent circuits, which is followed by the experimental confirmation. Furthermore, the the optimum design of its surge-snubber capacitor is presented.