Iron Loss Modelling and Material Property Degradation - Effects of Cutting Techniques, Material Variations, and Sinusoidal vs. Non-Sinusoidal Flux Distribution
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Electric power engineering (MPEPO), MSc
Publicerad
2024
Författare
Nygren, Emelie
Einarsson, Ulrika
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Abstract
With the electric vehicle industry expanding rapidly, there is an increasing demand for high efficiency in electric machines (EM). In order to achieve that, there is a need to have precise modeling of the EM and its losses. In this thesis, the iron loss degradation in EMs due to cutting during the manufacturing process is studied. Measurements were conducted on laminates of electrical steel with sinusoidal
and Pulse Width Modulated (PWM) flux density and the results were analysed and compared. Further, measurements on materials cut with punching and laser cutting were compared as well as materials cut in the transversal and length directions. The results from the measurements were used to model the degradation and iron losses and to perform a Finite Element Method (FEM) simulation of a Permanent Magnet Synchronous Machine (PMSM) with sinusoidal current excitation in Ansys Maxwell. From the measurements, it was concluded that all investigated materials were degraded due to cutting during the manufacturing process. The materials that had been cut using punching had better magnetic properties and lower losses than the ones that had been laser cut. The samples cut in the length direction showed significantly higher permeability than the ones cut in the cross direction but had higher degradation effects when compared to the uncut material. The effect of thickness on the sheet were compared for one punched material, the result is that thinner materials had better magnetic properties than thicker ones. However, the thicker materials were less affected by degradation when compared to the uncut material of the same thickness. The measurements with PWM had substantially higher losses than the sinusoidal measurements but the degradation effects were similar for both types of feeding. PWM feeding with higher frequency modulation ratio and higher modulation index both yield lower losses. From the FEM simulations, it was seen that the degraded machine models showed an increase in iron losses of up to 24 %
which resulted in a decrease in efficiency of up to 0.12 percentage points.
Beskrivning
Ämne/nyckelord
Keywords: iron losses, electric machine, punching, laser cutting, PWM, SST, Epstein frame, FEM, degradation, manufacturing effects