To meet the increasing power demand of today's spacecraft systems, an integrated power electronics system capable of interfacing, and simultaneously controlling, three power ports is proposed in this project. This new proposed power electronic architecture employs a single-stage power topology, thus allowing cost-effective control of power flow with improved efficiency, power density, and reliability. The project is developing an innovative, dc-dc converter which can effectively manage the interface of a source, a load, and an energy storage function within a single-stage, three-port topology. Modern advances in digital control, in conjunction with a novel power processing concept make this logical next-step possible. This unique topology and controller function together to realize three power processing paths which simultaneously utilize the power devices, allowing increased functionality while promising reduced losses and enhanced power densities. Control objectives include battery charge regulation, solar array peak power tracking, and/or load voltage regulation. The Phase I efforts completed the preliminary analysis and the proof-of- concept prototyping. A demonstration test was successfully conducted substantiating feasibility. Phase II will focus on system level control in order to demonstrate the concept in a relevant application with a solar array source, a lithium-Ion battery, and an electronic load bank as the bus.