Modeling and Verification of AC Impedance of Medium-frequency Transformer Considering Non-Current-carrying Conductor

In high-capacity applications, the AC impedance value of the medium-frequency transformer (MFT) can be significantly affected by the eddy current effect of the non-current-carrying conductors. However, existing calculation methods ignore this problem. This article focuses on the AC impedance modeling and analysis of the MFT considering the non-current-carrying conductor. First, an analytical method for calculating the leakage inductance of the MFT, which considers the non-current-carrying conductor, is introduced. Based on the method, the analysis of influencing factors is performed to establish the relationship between the leakage inductance and the design parameters of the non-current-carrying conductor. The finite element method (FEM) electromagnetic model of the MFT prototype is established to verify the analytical method. Second, the eddy current effect of the irregular conductor clamp is considered in the FEM model, and the contribution of each non-current-carrying conductor to the AC resistance and total loss is analyzed. Finally, the proposed models are verified by a 1kHz/800kW MFT prototype.