This paper presents a design of buck-current-fed full-bridge zero current switching converters which are suitable for high-power high-voltage DC applications. This study shows the capability of incorporating the step-up transformer parasitic components to get the zero current turn-off characteristics for full-bridge switches. The buck stage of the converter uses pulse-width-modulation control to regulate the output voltage and the full-bridge stage operates at a constant on time mode to implement soft-switching commutations. In this study, the converter model is derived, and this model is implemented in an IsSpice circuit, which can reveal the transient characteristics of the converter. Steady state analysis of the converter is also presented. Finally, the simulation results of this converter for the application of coupled cavity traveling wave tube are given and major design issues are discussed.