On the Calculation of the Leakage Inductance in Transformers With Nonideal Windings

Abstract

The transformer leakage inductance (TLI) is an important parameter in the design phase of the isolated power supplies. Hence, the TLI estimation before the transformer construction is very useful for the designers. The previous works considered an ordered winding turn arrangement (WTA) for the transformers. This assumption considers only ideal windings which may result in a significant error from what will be achieved after the construction of the transformer. This article concentrates on the transformers with nonideal windings in which the turns are not ordered. The uneven distribution of the turns in the layers is mainly due to the wrapping machine error. Hence, for a specific transformer with determined electrical specifications, different WTAs will be possible. Thus, the corresponding TLIs will be different. This will cause uncertainties about the TLI values for the designer. The article proposes a method for considering a large number of possible WTAs of nonideal windings. Hence, the proposed method can be used as a probability tool to plot the probability distribution of the TLIs. Furthermore, based on the obtained results, effective guidelines are recommended for the designers to avoid critical situations according to the transformer specifications. The accuracy of the method is evaluated using finite-element (FE) analysis and experimental measurements. The FE and experimental results both are in conformity with the statistical analysis of the article.