Loss parameter identification of a welded ring core lamination of NO-electrical steel

Abstract

Lamination packaging processes such as welding lead to a significant material degradation of non-oriented (NO) electrical steel sheets. Increase in iron loss and decrease in permeability are the results of the deterioration. For an efficient modeling of a drive train, the accurate parameterization of the iron loss is of upmost importance. For this reason, the iron loss model is expanded to include the influences of welding procedure. Its influence can be classified into changes in the grain size diameter $\left(d_G\right)$ and residual stresses $\left(\sigma \right)$. In this study, a locally varying iron loss model for the simulation of effects of weld-packaging on the electromagnetic properties of non-oriented (NO) electrical steel sheets is presented. Packaging technologies such as interlocking, welding, clinching and gluing are typically utilized for the manufacturing of electric steel stacks of electric machines. Understanding the micro-structural changes due to the macro-structural degradation accruing to weld-packaging helps in the accurate understanding of its influence on the performance and achievable range of the electric vehicle. Five (5) electric steel probes are annealed for the modeling of the local varying iron loss model at five different temperatures and electromagnetically measured to determine its magnetization and loss values. This will help in determining the grain size dependency of the different loss parameters. The annealed probes are measured under mechanical stresses showing also the residual stress dependency.