Thermal analysis of high-frequency transformers using finite elements coupled with temperature rise method

In this paper, a three-dimensional (3D) thermal model of a high-frequency transformer is presented. The finite element method (FEM) is used to solve the 3D steady state and/or transient heat flow equation which describes the thermal model. The local losses are initially estimated from electromagnetic field analysis based on the FEM, then, a method for recalculating the loss distribution based on the principle that the initial rate of rise of temperature at any point is proportional to the loss generated at that point. More accurate temperature distributions within the transformer are then computed from the resulting loss density distribution. The validity and accuracy of the proposed method are checked by comparing the results with those obtained from test.