Amorphous modular transformers and their 3D magnetic fields calculation with FEM

Abstract

Purpose -The purpose of this paper is to examine the calculation of magnetic field distribution in the modular amorphous transformers under short-circuit state including the flux by the voltage supplying. The magnetically asymmetrical transformer (amorphous asymmetrical transformer -AAT) has been compared also with the symmetrical one (amorphous symmetrical transformer -AST). Design/methodology/approach -3D field problems were analyzed with total c and reduced f potentials within the finite element method (FEM). The calculated fluxes have been verified experimentally. Findings -The field method which includes voltage excitation is helpful for flux density (B) calculation and winding reactances determination, as well. Calculations and tests yield similar flux distributions in both AST and AAT constructions. One should emphasize that AAT is better for manufacturing and repairing. Research limitations/implications -Owing to very thin (80 mm) amorphous ribbon, the solid core has been assumed for computer simulations.

Magnetic flux distribution in the amorphous modular transformers

“…To model the field, we considered unbalanced amperturns in each phase. Thus, this way we included no load current in the mathematical model that simulates voltage excitation [7,11].…”

A Comparative Analysis of Axial and Radial Forces in Windings of Amorphous Core Transformers

“…Under the normal operating conditions, the electromagnetic forces (EMFs) acting on the windings are small due to the relatively small magnitude of the leakage flux. However, under the short-circuit condition, the electromagnetic *Corresponding Author Email: doanthanhbao@qnu.edu.vn (B. D. Thanh) forces (EMFs) generated as a result of the interaction between the leakage flux and the short-circuit current are very large, this can lead to translation, destruction, or even explosion of the windings (6)(7)(8)(9)(10).…”

Computation of electromagnetic forces in the windings of amorphous core transformers

“…Consequently, the distribution of the electric field and the distribution of forces on the windings of the transformer are uneven. In addition, the insulation strength and winding strength of the amorphous transformer will be worse than those of the silicon steel core transformer [13,14].…”

“…These faults will make a very high EMF or mechanical force in the windings [15]. This EMF is split into two components, i.e., axial force (𝐹 𝑥 ) and radial force (𝐹 𝑦 ), where 𝐹 𝑥 is generated by the interaction of the current in the winding and the axial leakage magnetic field (𝐵 𝑦 ) being perpendicular to the winding axis, and 𝐹 𝑦 generated by the interaction of the current in the winding and the horizontal leakage magnetic field (𝐵 𝑥 ) being parallel to the winding axis [3,5,14,15].…”