Joint punching and frequency effects on practical magnetic characteristics of electrical steels for high-speed machines

• Published in: Journal of magnetism and magnetic materials Vol. 426; pp. 658 - 665
• Main Authors: Kedous-Lebouc, A., Messal, O., Youmssi, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.03.2017; Elsevier BV; Elsevier
• Subjects: Aging aircraft; Alloys; Automobile industry; Automotive engineering; CoFe; Core loss; Degradation; Electric power; Electrical sheets; Electrical steels; Engineering Sciences; Frequencies; Frequency; High speed; High speed machining; High-speed electrical machines; Industrial applications; Losses; Magnetic characterization; Magnetic permeability; Magnetic properties; Magnetism; Modeling; Parameter estimation; Punching; Punching impact; SiFe; Steel; Teeth; Magnetic characterization; SiFe; Losses; Frequency; High-speed electrical machines; CoFe; Electrical sheets; Modeling; Punching impact
• DOI: 10.1016/j.jmmm.2016.10.150
• ISSN: 0304-8853

Mechanical punching of electrical steels causes a degradation of their magnetic characteristics which can extend several millimeters from the cut edge. So, in the field of industrial applications, particularly that of small electrical machines, the stator core made of rigid and thin teeth would be subject to more losses. Thus, this topic of the effect of punching has to be submitted to further deep characterization and development in order to give some insight into the different mechanisms. In this framework, this paper evaluates the combined effect of punching and frequency on the magnetization curve and iron losses in thin SiFe and CoFe soft magnetic sheets. These alloys are typically suitable for the manufacture of high-speed electrical machines used in on board applications (aircraft power generators, automotive, etc). Two SiFe alloys and a CoFe alloy have been investigated. First, different rectangular samples of variable width (15, 10, 5, 3mm) have been industrially punched. Then, a dedicated magnetic characterization has been made, using basically a mini-Epstein frame. Measurements have been performed from 50Hz to 1kHz and from 0.3T to near saturation. Both rolling and transverse directions have been considered. Finally, a first attempt to predict the degradation due to the punching is presented. A useful description of the magnetic permeability as a function of B and f is given and the degradation parameters are estimated based on the knowledge of the reference permeability.