Determination of Local Magnetic Properties

This project is part of the current German-Austrian CRC/Transregio 361 Computational Electric Machine Laboratory: Thermal Modelling, Transient Analysis, Geometry Handling and Robust Design being a cooperation between Technische Universität Darmstadt, Technische Universität Graz, and Johannes Kepler Universität Linz.

For manufacturers of electric motors the precise knowledge of local magnetic properties and a model for accurately estimating the hysteresis losses is of utmost importance for the design process. The goal of the project is the development of a combined method based on measurements, 3D simulations and inverse schemes to locally determine the magnetic properties of electric steel sheets and iron cores as used in electric machines. This will allow us to provide local information about the following magnetic properties: losses, magnetisation, coercive field, virgin curve, hysteresis loops, commutation curve, etc. In particular, we will be able to determine, e.g. the change of the magnetic properties of ferromagnetic materials after being cut, punched, welded, etc. In doing so, we will develop a physically consistent vector hysteresis model being able to predict both alternating and rotational losses. In addition, the hysteresis model needs the capabilities for fast evaluation and has to allow an implementation in different Finite Element (FE) formulations achieving fast numerical simulations. By the development of a new sensor-actuator-system, we will be able to scan ferromagnetic materials and locally measure magnetic field intensity and magnetic flux density. Based on this measurement data, we will investigate in an appropriate inverse scheme being able to determine the parameters of the hysteresis model.