Recent improvements in magnetic material characteristics and switching device increased the possibility of replacing electrical buses with high-frequency magnetic-links in micro-grids. Multi-winding transformers (MWTs) provide a common magnetic bus for integrating renewable energies in the form of magnetic flux. Their application in multi-port converter makes it possible to simply integrate the sources with different voltage levels adjusting winding turn ratios. Other advantages are galvanic isolation, bidirectional power flow capability and simultaneous power transfer among the ports. Despite the above positive points modeling and characterization of MWTs is relatively complex due to the cross coupling and nonlinearity effects. This paper describes the experimental test procedures carried out on a toroidal core MWT to extract the parameters and to find the equivalent electrical model. Both prototype and resulted model are tested under different load conditions and are compared to verify the validity of modeling process.