Determination of Wound Core Transformer Losses and Temperature Rise

Abstract

Recently tape wound cores are widely used in transformers for power electronics applications. The spiral structure of theses cores affects the flux distribution inside the core and causes complication of magnetic analysis. In this paper, a model based on reluctance networks method is used for analysis of magnetic flux in toroidal wound cores and losses calculation. A Preisach based hysteresis model is included in the model to consider the nonlinear characteristic of the core. Magnetic losses are calculated by having the flux density in different points of the core and using hysteresis model. Additionally a thermal equivalent circuit is applied to determine the temperature rise in transformer due to the magnetic and electric losses. A transformer for using in a series resonant converter is modeled and the results are compared with experimental measurements to evaluate the validity of the model. Comparisons show accuracy of the model besides simplicity and fast convergence.