Cutting of the electrical steel sheets to appropriate shape and size is performed during the manufacturing of electrical machines which leads to the magnetic material deterioration near the cutting edge. Epstein frame measurements of electrical steel samples of different widths cut by laser cutting are carried out in the range of 20 Hz to 400 Hz frequency of sinusoidal excitations. Two stators one with laser cut and another one with electric discharge wire cutting were manufactured and the effect of cutting on core losses was analyzed. The effect of cutting on the magnetic permeability and core losses are modeled with analytical equations. Furthermore, the model is implemented in the finite element simulation of the Epstein frame test setup. The presented loss model is found to reproduce the measurement results reasonably. The loss model is then applied to the simulation of a cage induction machine with time-stepping finite element analysis. A significant increase in core losses was observed both in simulations and measurements due to the effect of laser cutting. The presented cutting model closely follows the measured core losses.

Manufacturing processes such as cutting, welding and shrink fitting are known to degrade the magnetic properties of the electrical sheet during the manufacturing of electrical machines. These effects are often neglected at the design stage and lead to large errors in the simulated and measured core losses of the electrical machine. This paper studies the comparative impact of different manufacturing processes on the stator core losses of a typical industrial motor. Both simulations and measurements indicate a significant impact of manufacturing processes on the stator core losses. A dummy blocked rotor test setup is used to measure the stator core losses. As a result of different manufacturing processes, the stator core losses increased by 23% in the studied machine at the rated condition. The effect on the stator core losses was higher at lower flux levels. Finally, it was shown that the inclusion of the effect of manufacturing processes significantly improved the simulation accuracy of the core losses. A quantification and segregation of the effect of cutting, welding and shrink fitting is also presented for the studied machine.

Various cutting techniques are in use as part of the manufacturing process of electrical machines such as laser cutting, punching, electrical discharge machining and waterjet cutting. The cutting process degrades the magnetic material near the cut-edge. This degradation results in lower magnetic permeability and higher core-loss density. This paper studies the effect of three different cutting techniques namely punching, waterjet and laser cutting on the magnetic properties of the grain oriented electrical steel sheets. A standard Epstein test confirms the different magnitude of degradation depending on the cutting technique. Further, a loss model based on the measurement results has been applied to the yokeless axial flux machine. The comparative analysis shows the superiority of the punching and water-jet cutting techniques over laser cutting which resulted in more than 150% increase in the core losses. Other machine performance parameters such as generated EMF and torque remain unaffected by the cutting method.

Cutting the electrical steel sheets to form the shape of the stator and the rotor affects the magnetic properties of the sheets. The increase of the magnetic losses as well as the drop of the magnetic permeability can impact on the design of electrical devices. This paper investigates this deterioration effect on the optimal design of the stator of a high-speed permanent magnet synchronous motor. The deterioration due to punching is phenomenologically analyzed based on measurement of strips of steel sheets with various widths on an enlarged Epstein frame. The losses are computed with a Bertotti model whose coefficients depend on the width of the sheets. The optimization of a synchronous machine is then carried out with this magnetic losses model.

As a part of manufacturing of electrical machines, electrical sheets are cut to the desired shape by various cutting techniques, such as punching and laser cutting. This cutting process degrades the magnetic material near the cut edge, which should be included in the finite-element modeling of electrical machines. However, due to the nature of the cutting effects, the existing finite-element modeling of the cutting effect results in computationally heavy simulations. This paper investigates the application of mixed-order elements to model the cutting effect. The second-order nodal triangular elements are used near the cut edge, whereas transition/first-order elements are applied in the remaining solution domain. Furthermore, the accuracy of the presented method is analyzed with the traditional method. According to the simulations, the mixed-order elements returned accurate results significantly faster than the traditional finite-element-based approaches. Furthermore, the effect of the cutting on the machine performance is also studied by comparing its results briefly.

Numerical modeling of energy efficient electrical machines requires accurate and fast calculation of losses. One such loss component is core losses related to magnetic material degradation due to the cutting of electrical sheets. This paper analyzes the application of higher order finite elements for precise and computationally efficient modeling of these cutting related losses. The accuracy of higher order elements is compared with highly dense first order elements. Finally, a time-harmonic model of an induction machine with presented higher order elements is simulated and effect of cutting on performance parameters has been analyzed.