A class of single-step high-voltage DC-DC converters with low voltage stress and high output current capacity

A multiphase converter suitable for a very high input voltage is proposed. It is formed by n switch pairs in the primary-side, an n-phase isolation transformer, whose primary windings are connected with dc blocking capacitors, and an n-phase rectifier. The switching patterns applied to the switch pairs have a phase difference of 360deg/n. It features V_i/n voltage stress on the primary-side switches, which commute under a ZVS condition, and a high output current capacity. The current stress of the inductors and diodes in the rectifier is reduced to one-nth of the load current. Compared with the input-series connected modular converters, the proposed converter feature a half of the switches number, for the same voltage stress across them. The reduced conduction losses and soft-switching give a high efficiency: 88.3% measured for a 1500 V/48 V, 2 kW prototype.