Modeling and Control of a Multiport Power Electronic Transformer (PET) for Electric Traction Applications This paper proposes a multiport power electronic transformer (PET) topology with multi-winding medium frequency transformer (MW-MFT) isolation along with the associated modeling analysis and control scheme. The power balance at the different ports can be controlled using the multi-winding transformer’s common flux linkage. The potential applications of the proposed multiport PET are highpower traction systems for locomotives and electric multiple units (EMU), marine propulsion, windpower generation and utility grid distribution applications. The complementary polygon equivalent circuit modeling of a MW-MFT is presented. The current and power characteristics of the virtual circuit branches and the multi-ports with general-phase-shift (GPS) control are described. The general current and power analysis for the multiple active bridge (MAB) isolation units is investigated. Power decoupling methods, including nonlinear solution for power balancing are proposed. The zero-voltage-switching (ZVS) conditions for the MAB are discussed. Control strategies including soft-switching-phase-shift (SSPS) control and voltage balancing control based on the power decoupling calculations are described. Simulations and experiments are presented to verify the performance of the proposed topology and control algorithms.