In this paper, steady and dynamic performance of a multi-input buck--boost DC--DC converter is presented. The converter has the ability to supply energy from storage and renewable energy sources individually to the load. It maintains a constant output voltage under various transient conditions of load as well as source. It has the capability to operate in buck, boost, and buck--boost modes of operation. The mathematical model of the converter is developed, which is further used to design controllers for the converter. A laboratory prototype is developed for experimental realization of the converter. The analysis, design, simulation, and experimental results of the converter prove that it is suitable in hybrid electric or renewable energy systems application.