Magnetic dipole collectives for modelling the ferromagnetic material characteristics in electrical machines

• Applicant: Professor Dr.-Ing. Ingo Hahn
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 393466659

• Final Report Year: 2023

Final Report Abstract

For the calculation and design of electrical machines, knowledge of the ferromagnetic material behavior of the used electrical steel sheets plays a crucial role with regard to the predictable operating properties and the losses occurring in the iron-containing regions. Generally, a magnetization characteristic curve is used in the numerical field calculation for the analysis of electrical machines, which results from the closing points of measured hysteresis loops of different excitation (commutation curve). However, the concrete shape of the respective hysteresis is not taken into account, although it contains all information about the occurring losses. The classical Steinmetz equations and their extensions are still used to calculate the losses due to remagnetization and eddy currents occurring in the iron-containing regions. Despite the fact that in recent years other modeling equations (Bertotti, IEM-Model, Pry-and-Bean, and others) have been introduced, which show improved predictive capabilities, they still show deviations from the real losses occurring in an electrical machine. In the field of electrical machines, simulations on the micromagnetic level lead to an extremely high algorithmic complexity. The dipole collective model, however, is able to predict the measured BH trajectory with moderate temporal effort with sufficient accuracy, so that it is very well suited for the investigated application and for the description of the dynamical ferromagnetic behavior in the active components of electrical machines. The core idea is to approximate the magnetic domain of ferromagnetic materials by magnetic dipoles, which are mounted rotatably. When applying an external field excitation, the dynamics of the individual dipoles is modeled using the Landau- Lifshitz equation, while the rotational motion is realized by Newtonian mechanics. The use of Newton mechanics allows to avoid the computationally expensive precessional motion of the dipole (quantum mechanics) postulated by the Landau-Lifshitz model. Therefore, the dipole collective model does not claim to be physically accurate, but is rather located in the area between micro- and macromagnetism. Interestingly, despite the simplified approach, the rotatably mounted dipoles exhibit hysteresis behavior and are able to reproduce it adequately.

Publications

• Influence of turning on the magnetic properties of electrical steel in the production of electrical machines. 2011 IEEE International Electric Machines & Drives Conference (IEMDC), 83-88. IEEE.
  Boehm, Andreas & Hahn, Ingo
  
• Comparison of soft magnetic composites (SMCs) and electrical steel. 2012 2nd International Electric Drives Production Conference (EDPC), 1-6. IEEE.
  Boehm, Andreas & Hahn, Ingo
  
• A simple method for the parameter identification of the Jiles-Atherton model using only symmetric hysteresis loops. IECON 2013 -39th Annual Conference of the IEEE Industrial Electronics Society, 2571-2577. IEEE.
  Lindner, Andreas; Hahn, Ingo & Bohm, Andreas
  
• Messung magnetischer Materialeigenschaften und deren Berücksichtigung bei der Simulation elektrischer Maschinen. Zugl.: Erlangen-Nürnberg, Univ., Diss., 2015.
  A. Böhm
  
• “Erweiterung eines 3-dimensionalen magnetischen Dipol-Kollektivs zur Beschreibung ferromagnetischen Materialverhaltens,” Master Thesis, Lehrstuhl für Elektrische Antriebe und Maschinen, Universität Erlangen Nürnberg, Erlangen, 2015.
  Christoph Hittinger
  
• Phenomenological modelling of ferromagnetic hysteresis using three dimensional dipole collectives. 2016 XXII International Conference on Electrical Machines (ICEM), 1983-1988. IEEE.
  Wagner, J.; Hahn, I. & Hittinger, C.
  
• Examining the unstable behaviour of a phenomenological three dimensional, dipole-based hysteresis model. 2017 20th International Conference on Electrical Machines and Systems (ICEMS), 1-6. IEEE.
  Wagner, Johannes; Hittinger, Christoph & Hahn, Ingo
  
• Influence of elementary model parameter variations on simulated ferromagnetic hysteresis using a ring-shaped 3D dipole collective. 2017 20th International Conference on Electrical Machines and Systems (ICEMS), 1-6. IEEE.
  Hittinger, Christoph; Wagner, Johannes & Hahn, Ingo