Magnetic and Electric Characterization of Materials for Electrical Machines by M.S.Muhit -Royal Institute of Technology School of Electrical Engineering Electrical Machines and Power Electronics

Magnetic and Electric Characterization of Materials for Electrical Machines 
by M.S.Muhit
 Master Thesis
Royal Institute of Technology School of Electrical Engineering Electrical Machines and Power Electronics Stockholm, August 2011
 Abstract
This thesis aims to characterize materials for electrical machines. Electromagnetic properties (b-h curves) and electrical resistivity were the main properties investigated in the project work. Two types of samples are considered: stator lamination sheet and rings made of steel used for structural pieces in large AC machines. To facilitate magnetic characterization experiments, an existing test setup was upgraded. Sensors and amplifiers have been developed. The control system has been upgraded and developed SIMULINK modules have been adapted to dSPACE GUI. The retrieved ‘B’ and ‘H’ signals are processed offline to obtain the results. The lamination sheet has been tested for frequencies in the range [0.1-150 Hz] and flux density levels up to 1.5 T. The obtained results depict characteristics hysteresis curves and measured loss figures. The ring samples (structural steel) are characterized to explore the B-H curves at frequencies in the range [0.1-250 Hz] and field intensity up to 900 A/m. For resistivity measurements of the lamination sheets and ring samples, standard resistivity measurement techniques have been implemented. Keywords Magnetic properties, Epstein frame, hysteresisgraph, four point probe, resistivity measurement, soft magnetic material, electrical steel.
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http://www.diva-portal.org/smash/get/diva2:470656/fulltext01

Measurement research on magnetic properties of electrical sheet steel under different temperature, harmonic and dc bias Dezhi Chen - Li wei Fang - Byung-il Kwon School of Electrical Engineering, Shenyang University of Technology

Measurement research on magnetic properties of electrical
sheet steel under different temperature, harmonic
and dc bias
Dezhi Chen - Li wei Fang - Byung-il Kwon
School of Electrical Engineering, Shenyang University of Technology,
 Shenyang, China


I. INTRODUCTION 
The phenomena such as the DC power grid, geomagnetic storms change, DC voltage of converter transformer may result in DC bias. Then the DC bias leads to the magnetic leakage flux increase in cores, metal structure losses, temperature rise, local overheating, dielectric breakdown, noise vibration, even the permanent damage to transformer.1 Meanwhile, the rise of temperature and harmonic will also affect the magnetic properties of electrical sheet steel. Manufacturers of electrical sheet steel can provide magnetic parameters, such as loss of iron core, that usually are measured at room environment temperature. The measured electromagnetic performance of transformer has a certain error compared with the actual operation temperature.2 When temperature, harmonic and DC bias change at the same time, the transformer operation condition will be more complicated. This paper is the first time to present the measurement research on the magnetic properties of oriented electrical sheet steel considering both different temperature and DC bias, and it shows the curve of magnetic properties under different temperatures (40 °C to 150 °C), frequency(50Hz to 4.5kHz) and DC bias (0A to 2.0A). It can provide a useful guidance for the design and optimization of power transformer

LINK ORIGINAL
http://aip.scitation.org/doi/pdf/10.1063/1.4979490