Electric Steels for Automotive Traction Electrical Motors

Improving the performance of electric vehicle traction system can improve their autonomy without increasing the amount of batteries. In the case of electric motor, a compromise is necessary between power density and efficiency: more one charges the motor, more its efficiency tends to deteriorate because the increase in current density on the one hand, the magnetic flux density on the other hand, have a negative effect on Joule losses and iron losses. One way to offset this trade-off is to use materials with different characteristics. FeCo sheets, very efficient, are disqualified by their price; SMC iron powders are potentially interesting at high frequency but their lack of medium frequency permeability confines them to specific applications. GO sheets are commonly used in transformers, but not in electric motors. Indeed, their strong anisotropy (magnetic characteristics better in the axis of lamination than in the other directions) prevents them from being used for parts with symmetry of revolution (sheet of motor with radial flux). However, their magnetic performance superior to that of the NO sheets encourages search for solutions that could allow their use in motors as the segmentation of the sheet package. The purpose of this thesis is to quantify the limitations associated with certain possible solutions to manage the anisotropy of these GO sheets in the motors. This work implements simulation activities (including modeling of sheet anisotropy) and experimental work. In short, this thesis shows: ??- a general overview of GOES; ??- the use of GOES in rotating field machines; ??- a sizing 15/10 radial flux motor with concentrated winding around the teeth starting from a Prius TOYOTA motor; ??- a study of the anisotropy of GOES using the finite element software of Ansys (Maxwell); ??- a measurement system to identify the macroscopic characteristics of the sheets; ??- some experimental results on the macroscopic characterization of GOES and NGOES at 50Hz, 250Hz, 500Hz and 600Hz; ??- possible experimental devices that allow to study what happens in the tooth root of an electric motor.