Analysis and Modelling

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The workgroup deals with the characterization and modeling of the magnetic core and insulation system and their effect on the operational characteristics of electrical machines. Therefore, specialized experimental characterization methods are utilized as well as modeling and model coupling for ferromagnetic materials and isolation materials. Current topics such as the production influences, life time analysis, partial discharge or anisotropic material behavior are research objectives. Depending on the problem, specific solutions and problem-oriented approaches are developed.

Another main research topic is the appropriate modeling of loss effects. Special numerical and analytical models are developed for hysteresis effects, eddy current losses and various types of magnetization. Influences of the production and processing of electrical steel, texture and microstructure originated anisotropies, mechanically induced stress as a result of cutting or embossing and the influence of packaging by welding and interlocking is experimentally studied. For standardized characterization, four Epstein frames, as well as four Single-Sheet-Testers with 120 mm x 120 mm and 60 mm x 60 mm as well as a ringcore tester are available. A ring core winding machine allows flexible winding numbers. Besides the conventional characterization methods, the material lab has advanced characterization equipment. Losses occurring at rotating magnetizations can be measured with an Rotational-Single-Sheet-Tester (RSST). Furthermore, a miniature, SST for the characterization of single crystals, a Tensile and compressive SST and universal tensile tester with magnetization yoke and vector hysteresis sensors. With this advanced and novel methods and many different interdisciplinary research projects, we have garnered the expertise to study, quantify and model material related effects of electrical steel.

Within lifetime investigations, comprehensive lifetime models are developed, which allow the calculation of the expected lifetime with a probability for different loads. Therefore, modern measuring devices, a climate chamber, heating ovens and a vibrating table are available. Electrical insulation systems must be qualified for operation on voltage converters. Inverters with fast switching silicon carbide (SiC) semiconductors are in focus of current research work.

In collaboration and exchange with the other workgroups, our competence allows specific solutions depending on the scientific and technical problem. The focus comprises the interaction of machine ↔ magnetic material and insulation system ↔ lifetime. The consideration of different effects within the FE-simulation and post processing allows comprehensive evaluations. Furthermore, a validation can be obtained with additional demonstrator measurements.

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