Comparison and Verification of Boost Control Methods for Full Soft-Switching Bidirectional Current-Fed Isolated Full-Bridge DC-DC Converter

There are numerous galvanically isolated current-fed step-up dc-dc converter with soft-switching. Usually, soft-switching is associated with circulating energy that causes additional power losses and duty cycle loss. At the same time, the output voltage is stabilized by means of the shoot-through duty cycle control. However, new control possibilities were enabled in the novel concept of full soft-switching clampless current-fed converters that were introduced recently. Those converters feature controllable circulating energy, which can be used for improvement of the voltage step-up performance together with the shoot-through duty cycle control. This paper is focused on experimental comparison of two different methods of voltage step-up regulation for the full soft-switching clampless current-fed converters using full-bridge topology. These methods are compared in terms of power losses, input current ripple level, regulation range, etc. Theoretical findings were corroborated by means of 300 W experimental prototype.