Application of grain-oriented electrical sheets in flux switching machines

• Applicant: Professor Dr.-Ing. Ingo Hahn
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: from 2019 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418147303

The design of efficient electrical machines with high torque density is a really challenging task. In accordance with the achievement of the given goals for the reduction of greenhouse gases some other goals to reduce the energy consumption could also be met. Therefore, the electrical machine, as an electro-mechanical transducer, plays an important role. Despite the optimization of the geometry of the electromagnetically active parts of the electrical machine towards energy-efficiency, the application of new machine topologies and materials should be considered, which is the main task of this research project. On the basis of some early stage numerical simulation results the application of grain-oriented electrical steel sheets in a new machine concept, the flux switching permanent magnet machine (FSPMM), with a segmented stator structure will be investigated.To evaluate the inherent potential of applying grain-oriented electrical steel sheets, these materials should be characterized in a first step. For the characterization of the material a very specific test set-up has to be developed, which is able to investigate the electromagnetic characteristics as well as the influences of the cutting edges and the joint edges depending on the rolling direction of the steel sheets. Based on the gained results, a decision in view of the cutting and joining method should be made.Next, the machine's operation behaviour will be modeled analytically with a simple magnetiac equivalent circuit (MEC) model, because of the resulting lower computational burden of this method. Despite the modelling of the machine's geometry, the influences of the cutting methods and the segmentation of the stator will be modeled and considered in the MEC.After achieving some preliminary results of the operation behaviour of the machine while using the MEC, the final design for the machine's prototype will be accomplished by applying the Finite-Element analysis. At this stage of the project a decision has to be made, where to use the grain-oriented electrical steel sheet within the active machine parts. Furthermore, the influence of the material cutting methods and the influence of the micro-airgaps at the joint edges of each single segment of the stator structure should be taken into account. Finally, the designed prototype machine will be built-up and integrated in a test-setup.The prototype will be tested according its operation characteristics like torque, cogging torque, power density and efficiency. To evaluate the advantages of applying the grain-oriented material in a FSPMM a comparison with an existing FSPMM with non-grain-oriented electrical steel sheets, which already exists at the institute, will be performed. The overall goal of this project it to prove the expected increase in power density and efficiency of the said FSPMM while using grain-oriented electrical steel sheets.

• DFG Programme: Research Grants