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Technischer Magnetismus

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Research Areas

The focus of the recent activites is given by the following five fields of research:

I. Combined 2D/3D assembling of ultra-thin sensor bands (with ABB-Transformers, Sweden; FWF-project "Mag Foil Sensors)

A computer-controlled assembler is developed that allows for the manufacturing of multiple sensors on a substrate foil of about 20 µm; thickness and up to 1 m length. 2D printing technologies are combined with 3D ones, in specific ways for conducting and non-conducting print materials. Detected quantities comprise 3D magnetic induction components, mechanical strain (magnetostriction), temperature (energy losses) and vibrations. Minimum thickness of complex sensors take a advantage of thin nano-crystalline or amorphous sensor-nuclei. The detector bands are designed for flexible arrangement in machine cores at different locations, connections to electronics being arranged externally. For diagnoses of machine faults, it is planned that the detector bands remain within the core in permanent ways, to be contacted in cases of demand.

II. Experimental analyses of magnetic machine cores

The focus is put on 3D distributions of magnetic fluxes, energy losses, strains and audible noise generation in transformer cores assembled of novel laser-scribed silicon iron. We apply very different sensor types that partly are moved by a computer-controlled scanning system. This enables detailed analyses though fully-automatic over-night processing. As a main conclusion of current work, modern cores represent complex 3D systems, due to their multi-package design. The individual packages prove to be in interactions that vary with time. In comparisons to model cores, industrial cores reveal less defined mechanisms.

III. Numerical analyses of magnetic machine cores (with ABB-Transformers, Sweden) -

Apart from applying Finite Element Modelling, the focus is put on MACC (Magnetic Anisotropic Circuit Calculations), a completely novel own methodology. With very rapid processing, it yields compact numerical images of flux distributions, including data on local flux distortions and dynamic rotational magnetization. For straigt-forward optimization of the involved algorithms, the next step will be concentrated on theoretical aspects of modelling.

IV. Rotational magnetization tests (with JFE Steel Corp., Japan, and Nippon Steel & Sumitomo Metal Corp., Japan) -

Rotational magnetization enhances both losses and audible noise in all three transformers, shunt reactors and rotating machines. With a world-wide unique hexagonal Rotational Single Sheet Tester (RSST), we characterize novel types of materials, e.g. of minimum thickness, with novel stress coatings, or for compact motors that are specifically designed for electro-mobility. The industrially relevant results of the RSST concern time patterns of induction vector and field vector, energy losses, magnetostriction and domain configurations.

V. To-be-standardized magnetic metrology (with ABB-Transformers, Sweden, and voestalpine Linz) -

Since more than hundred years, energy losses of magnetic materials are determined by means of testers that simulate complete magnetic circuits. In particular, this is valid for Single Sheet Testers and Epstein Frame Testers. In recent theoretical work, we found that these IEC-standardized testers exhibit systematic errors, since not considering dynamic changes of instantaneous flux distributions. We now developed a concept for a novel methodology that should enable "physically correct" results, actual demand coming from severe world-wide energy politic and from electro-mobility. The final target is to suggest the method for international standardization.