Fast Characteristics Calculation of Large Transformers With Step-Lap Joints by Dividing Regions of Finite-Element Analysis

This article describes a fast characteristics calculation of large transformers with step-lap joints by dividing regions of finite-element analysis (FEA). The flux of the core in each divided region is given by fixing the magnetic vector potential at the divided surface due to Stokes' theorem. The exiting current of the coil is calculated from the magnetic field with Ampere's law. The validity and advantage of the proposed method are confirmed by comparing the calculated iron loss and exciting current with those of the FEA applied to the whole region. The usefulness of the proposed method is clarified by the application of characteristics improvement of the transformers.