A Study on Stray Loss Calculation in Power Transformer using Impedance Boundary Condition

In this paper, we proposed an efficient numerical modeling to predict the stray loss generated in transformer tank. Generally, 2-D axisymmetric model is used to reduce the computing time. However, 2-D axisymmetric model is different from the actual transformer model due to its complex geometrical shape. So, we have to use 3-D model to get the accurate analysis results. Using 3-D model, we apply the impedance boundary condition on the outer surface of the transformer tank. In this case, the computing time reduces since the total number of meshes becomes smaller. To verify the validity, A prototype was manufactured, and experiments were performed. The validity was verified by comparing the magnetic flux density measured by the experiment with the magnetic flux density calculated by the analysis. The proposed analysis technique is expected to be useful to reduce computing time and to get the accurate results.