General equivalent circuit of a multi-winding co-axial winding transformer

This paper addresses the general equivalent circuit of a multi-winding coaxial winding transformer (MCWT). Unlike conventional winding transformers with more than three windings, the high frequency equivalent circuit of an MCWT can always be reduced to a T-type circuit model. This is due to the physical construction of the transformer and the high frequency skin effect which causes the current within the windings to be unevenly distributed. The uneven current distribution results a very weak leakage coupling between each of the secondary windings. Therefore, each secondary winding can be treated as an independent coil which results in a minimum number of inductance branches in the equivalent circuit representation. The leakage coupling between secondary windings mainly comes from the end lead leakage flux which can be reduced significantly by making the end leads short. Finite element analysis and experimental confirmation of the proposed equivalent circuit are given based on a ten-winding MCWT. The MCWT could have a large number of applications in industry and research fields.