Parameter Study on the Effects of Spot-welding on the Electromagnetic Properties of Magnetic Cores Constructed from Electrical Steel.

In this paper, a parameter study on the effects of spot-welding of thin electrical steel sheets is reported and evaluated by experimental measurements. Welding is a typical method to connect iron stacks of electrical machines. However, this process deteriorates the magnetic properties of the said electrical sheets, thereby increasing the iron losses and decreasing the magnetization of the magnetic core. The effects of three main welding process parameters namely: laser-power, laser focal position and working pressure are studied and evaluated. The dependency of the material degradation due to these parameters are quantified and metrologically characterized. In particular the approach of a stochastic spot-welding procedure is studied. This is due to its apparently less electromagnetic degradation, when compared to other welding procedures. Employing the stochastic spot-welding joins two or three single ring-shaped sheets together in an stochastic pattern, which reduces the eddy-current losses around the welded point.