The magnetic core of rotating electrical machines is usually constructed of stacked and fixed non-oriented electrical steel laminations. The process of stacking and fixing has a detrimental effect on the magnetic properties. Two main factors are the cause of the magnetic deterioration, namely the induced mechanical stress as well as increasing eddy currents due to a damage of the insulation layer between the sheets. As a result magnetic loss increases and permeability decreases. The presented novel welding strategy shows promising results to decrease the magnetic deterioration, especially as an approach for higher frequency applications Besides interlocking, linear welding is a common technique to join laminations to a package. The target of the fixation is to fulfill requirements of mechanical strength and torsional rigidity even at high speed of a rotor. However, the magnetic property change cannot be neglected. Electrical steel sheets are usually characterized in standardized tests of the steel sheets prior to the further manufacturing process. Machine design and machine simulation use this early data to estimate loss and magnetic behavior of electrical machines. The manufacturing processes is disregarded and actual machine behavior can significantly differ from the estimations. In order to improve understanding of the welding influence and study possibilities to limit its effect, this paper studies the effect of different welding approaches. Ring cores are stacked from 0.5-mm sheets of insulated industrial steel with a silicon content of 2.4 wt.%. The stacks are joined by laser welding at atmospheric pressure and under vacuum. Statistical distribution of single welding spots are studied alongside common linear welding lines across the entire height of the stack. The aim is to minimize the alteration of magnetic behavior while maintaining full load capacity. Magnetic ring core measurements are supplemented by microstructural analysis in order to determine the directly affected regions of the welding process. Differences of total loss, frequency behavior and magnetization characteristics are analyzed.


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    Title :

    Analysis of a novel laser welding strategy for electrical steel laminations


    Contributors:


    Publication date :

    2017-12-01


    Size :

    2071007 byte




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English