The Influence of Cutting Technology on Magnetic Properties of Non-Oriented Electrical Steel-Review State of the Art

The global drive to reduce energy consumption poses new challenges for designers of electrical machines. Losses in the core are a significant part of losses, especially for machines operating at an increased rotational speed powered by PWM inverters. One of the important problems when calculating core losses is considering the effect of material degradation due to mechanical or laser cutting. To this aim, this paper analyzes and summarizes the knowledge about the sources of material property deterioration and ways of describing this phenomenon. The cited results of material tests indicate the lack of unequivocal relationships allowing us to estimate the degree of material damage and the resulting deterioration of material properties. The main task of this article is to present the state of knowledge on the possibility of taking into account the impact of cutting the core sheets of electric motors on core losses and their impact on the efficiency of the machine. This is a significant problem due to the need to design and manufacture energy-saving electric motors powered with a voltage of 20 to 350 Hz, whose magnetic cores are made of laminates. However, the performed analysis indicates the most important parameters of the cutting process, affecting the degree of material structure destruction. The method of the solution proposed by the authors for core punching and laser cutting, illustrated with a practical example, is also presented.