Researchers: Folke Schwinning, M.Sc.
In its history, the Institute for Mechatronics in Mechanics has been working and conducting research on electric motors and generators from an early stage and has a machine test bench with state-of-the-art electrical, mechanical, and thermal measurement technology in its Power Hardware-in-the-Loop laboratory (PHILSLAB).
In the context of electromobility and the associated high demands on efficiency, power density, performance figures, and costs, numerous new areas of research are emerging. In this context, iMEK is researching new methods for multiphysical design and optimization of electric machines. The investigations are primarily conducted on axial-flux synchronous machines, which, due to their design, offer a wide variety of variants, great potential for innovative solutions, and promising performance.
Optimizations using conventional genetic algorithms or comparable methods already save a lot of time in finding the optimal design for a motor or generator based on a list of requirements. However, complexity is constantly increasing, meaning that this process still takes weeks or months and is computationally intensive.
To reduce this complexity, especially in light of rapidly changing requirements and multiple optimization goals (multi-objective optimization, MOO), an optimization framework is being developed at iMEK. Mechatronic systems, in this case electrical machines, are divided into smaller segments, for example into their physical domains, and modeled. The models are examined using Design of Experiments methods and metamodels are generated that approximate the behavior of the models as precisely and predictably as possible. With the metamodels, a broad design space can be completely calculated within a very short time and evaluated using simple cost functions.
This also makes it conceivable to use the methodology in the Engineer-to-Order process, in which customers receive a data sheet for a simulated machine that is optimal for them within a few minutes after specifying their requirements. This reduces development costs, so that only a sample validation is necessary before actual use and the optimal machine can be found for each application.
Optimizing electrical machines based on segmented models also leads to new approaches for segmenting and modeling multiphysical systems. Furthermore, empirically measured data can also be incorporated into the overall system model. At iMEK, 3D FEM simulations of the electromagnetic domain of axial-flux machines, Matlab and Simscape models of system behavior, thermal simulation models, CAD models with automated design, and much more are created.
Finally, verification and validation of all models is essential in order to generate designs for electrical machines whose characteristics are as close to reality as possible. In addition to the classic production of prototype machines and in-house measurement, individual components are also thoroughly examined. On a specially developed coil test bench, various prototype coil units are operated to test their behavior under different electrical control conditions (current density, DC, and frequency), different installation positions (air gap thickness, displacement, and tilt), and cooling parameters, and electrical, magnetic, thermal, and mechanical measurements are recorded.