Feasible method of calculating leakage reactance of 9-winding transformer for high-voltage inverter system

Calculating leakage reactance of transformers is a very important factor in designing transformers. In the traditional two-winding transformer, the calculation methods of leakage reactance have been presented using the inductance deduced by the geometry mean length between two windings. However, it is difficult to calculate the leakage reactance in multi-winding transformers, because its structure is more complex. Finite element method (FEM) is useful to obtain the characterization of the electromagnetic behavior of the magnetic components. FEM is an accurate method but its computational cost is very high. In this paper, the leakage reactance of 9-winding transformer was calculated by using an ordinary three dimensional FEM (3D FEM) and hybrid FEM which is a quasi-three dimensional analysis method. The comparison results show that the hybrid FEM is able to calculate the leakage reactance with a low computational cost.