This paper presents a converter design for fuel cell operations enhanced with a cooperation of supercapacitors and lithium batteries. The study is motivated because the properties of connected sources of fuel cell, lithium battery and super-capacitor are mutually different. An integrated converter with the energy control to regulate the power flow hence becomes crucially important. In the study, through the utilization of an improved step-down circuit along with the isolated circuit design, the completed converter is proved effective to supply power from fuel cells along with a backup support of supercapacitors and lithium batteries. By validating this proposed circuit under different load scenarios, test results help confirm the practical values of this design for green energy applications.