Leakage Inductance Calculations in Different Geometries of Traction Transformers

Abstract

Calculating leakage inductances between windings of traction transformer is one of the most important schemes in design procedure. In this paper, analytic, semi-analytic and finite element methods are introduced for electromagnetic modeling of different geometries of the traction transformer. Using these methods, the leakage inductances between windings are calculated and the methods have been validated with the help of a traditional analytic method and experimental data gathered from a typical 4000kVA dry-type transformer. The analytic method which usually used for electromagnetic modeling of transformers with concentric windings, assumes the windings to be constructed of straight wires. This method is fast and suitable for calculating the axial magnetic field and leakage inductance between concentric windings. However, in order to increase the accuracy of leakage inductance calculations between pancake windings, a semi-analytic method is proposed. It is shown that this semi-analytic method has a better accuracy in comparison with the analytic method and despite of the longer computing time, it is still a faster method compared to finite element.