Fraunhofer Institute for Mechanics of Materials IWMTransformers are key elements in energy technology, as they connect the different voltage levels of the power grid. The Enhanced LMDR project aims to further develop laser treatment technology for reducing losses in highly permeable grain-oriented iron-silicon sheets, which are used as core materials in distribution transformers, among other things. Remagnetizing the sheets using laser treatment leads to immediate savings in electrical energy during transformer operation.
Materials and process optimization to increase the efficiency of laser-treated grain-oriented electrical steel
Completed research project
Project description
Laser Magnetic Domain Refinement (LMDR) is a laser process technology that has been used industrially for 30 years to reduce electrical losses in highly permeable, grain-oriented electrical steel sheets used as core materials in distribution transformers. Depending on the starting materials and the laser process used, remagnetization losses can be reduced by 10 to 15% compared to untreated materials. However, the potential for further loss reduction is significantly higher.
In the “Enhanced LMDR” project funded by the BMWK (Federal Ministry for Economic Affairs and Energy), laser beam sources are being further developed to enable efficient domain refinement. The aim of the project is to increase the efficiency of grain-oriented electrical steel by improving its magnetic properties as a result of optimized laser treatment. In addition to optimizing the laser process, the aim is also to optimize the starting materials.
Increasing the efficiency of grain-oriented electrical steel leads to immediate savings in primary energy in transformer operation.
Fraunhofer IWM subproject:
It is known that residual stresses influence the formation of magnetic domains, but the fundamental influences of industrially treated sheet materials on the formation of residual stresses and the effect on the formation of magnetic domains are not fully understood.
Fraunhofer IWM is contributing its expertise in the field of residual stress analysis and simulation to the “Enhanced LMDR” project. The first step is to gain a better understanding of the internal stress distributions during laser treatment. The aim is to investigate the influence of process parameters on the internal stress distribution in Fe-Si electrical steel sheets and to use this knowledge to explain magnetization losses. The focus of the work is on the numerical simulation of the process and the analysis of the effects on internal stresses at different process parameters. The thermomechanical models used at the institute are capable of performing an in-depth parameter study of the process and providing reliable temperature, strain, and stress fields. The models are validated with residual stress analyses determined by X-ray diffraction (XRD) and synchrotron.
Transfer of project results to the following Fraunhofer IWM R&D services for companies:
- Residual stress analysis and quality control: Characterization of laser-induced residual stresses using X-ray diffraction (XRD) and synchrotron measurements for quality control and materials development.
- Simulation and process optimization: Thermomechanical simulations for predicting temperature, strain, and stress distributions and for process optimization in laser-based materials processing.
- Loss reduction and resource efficiency: Increased efficiency of transformers through optimized laser treatment of grain-oriented electrical steel sheets using LMDR.
