Sima Soltanipour Electrical engeneering

Sima Soltanipour is a PhD student in the research group Electrical machines and power electronics at the unit Electric power engineering.

Discussion leader is  Dr Torbjörn Wass, Lead Scientist Hitachi Power Grids

Examiner is professor Torbjörn Thringer, Chalmers

Abstract
A longstanding problem in the design of Electric Machines is precisely accounting for the core losses. Although the introduction of core loss models dates back to 1900, the discrepancy
between measurement results from actual machine and analytical calculation is about 70% to 100%. To tackle this issue, much research has been conducted which has successfully identified
some of the root causes of these discrepancies. The main known reasons are the effect of cutting to shape the stator and the rotor. The cutting effect may vary depending on the technique used.
The most common techniques to shape the stator and rotors of electric machines are punching, used for mass production, and laser cutting, mostly employed to build prototype machines. In
addition, shrink fitting of the stators into housing, welding or interlocking of stator stacks, and Pulse Width Modulation (PWM) to feed the machine with the inverter are contributing to the
losses in the iron core of electric machines which are not accounted for in the analytical calculation of the losses. Among these known reasons, this project is focused on the effects of manufacturing processes like cutting. The main contributions of this work are 1) Quantifying the impact of laser cutting by extensive measurement of the properties of electrical steels that have undergone laser cutting, 2) Mathematically modeling the degradation due to laser cutting 3) Implementation of the
degradation model in electric machines to quantify this impact on electric machines performance, 4) Drive cycle assessment of the laser cutting effect on a selected vehicle dynamic, 5) Comparison
of the impact of laser cutting on different electric machines’  topology. 6) Statistical assessment of the core losses in the ring cores due to geometrical properties, 7) Statistical comparison of core loss measurement techniques for laminated steel, 8) Quantification of core loss increase due to pulse width modulated excitation of laminated steels 9) Comparison of the impact of various cutting techniques on the properties of the laminate steels, 10) Comparison of the rolling direction on the effect of laser cutting on material properties