Utilizing residual stresses in electrical sheet metal to increase energy efficiency

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Increasing the efficiency of electric machines by conventional means has been mostly exhausted. Hence, novel approaches to unlock additional potential are needed. One possible solution is using targeted residual stress to locally tune the magnetic material properties and replace conventional flux barriers. Thus, new design possibilities for future electric drives are achievable. Electrical steel sheets without cutouts allow to increase the angular velocity of electric drives due to higher mechanical stability, resulting in an increased efficiency.Based on the validation of the fundamental principles for the creation of flux barriers during the first project period, we quantified the influence of residual stress on the electrical steel sheets. We have shown that electrical steel sheets with embossed flux barriers have an increased mechanical stability and allow higher angular velocities. We have furthermore analyzed that standard imprecisions in the embossing process only cause minimal changes in the magnetic properties. We validated our simulation models (mechanic and magnetic) using measurements with neutron grating interferometry, single sheet testing and nanoindentation. Connecting the results from the first phase with our simulations and measurements, we validated the residual stress measurements. In the third project period, we will use the results of the previous two periods to develop our research results for industrial applications. We will optimize and simplify our magneto-mechanic and micromagnetic models to analyze the material property improvement. Using the optimized simulation models we will continue to increase the effectiveness of our flux barriers as well as consider the influence of typical operating conditions (temperature and static and cyclic loads). Based on these results, we will model and optimize the magnetic flux in a demonstrator. The results will be compared numerically to the magnetic flux in a conventional demonstrator. Based on the optimized demonstrator, we will show the successful magnetic flux guidance. During these processes, we will further improve our measurement methods as well as perform validation measurements. Finally, a guideline for the development of embossed rotor geometries will be developed.