Influence of Cutting Process on Magnetic Properties of Electrical Steel

Abstract

This thesis provides a quantitative analysis of degradation of magnetic properties due to guillotine and laser cutting in non-oriented electrical steel sheets (M270-50A). Rectangular specimens of different widths are cut by guillotine and laser in order to obtain different rate of degradation in the material. The B-H characteristics and losses on these specimens are measured using a custom made Epstein frame under steady state sinusoidal flux density at various frequencies. Measurements results are used to analyse the change in permeability and iron losses. Total measured iron losses are separated into the classical and hysteresis loss components by using least-squares fitting to the well known Jordan model. A finite element model of a 37 kW induction machine is developed and the magnetic characteristics of the damaged and undamaged materials are implemented to the cut edges and the rest of the core material, respectively. Steady state finite elements simulations on the induction machine are performed using FCSMEK, an in-house finite element solver, in order to analyse the effect of material degradation on the losses.