Study of the magnetic behavior of non-oriented Fe-3%Si alloys used in magnetic machines

The prediction of core losses in a rotating electrical machine has been estimated by a numerical finite element method and the use of power losses measurement on a toroidal magnetic lamination (taking account of anisotropy) under sinusoidal induction. The predicted core losses are 40% lower than the mesured ones. This excess can be attributed to harmonics due to the rotor rotation and modification of the magnetic properties of the material due to the lamination punching and core assemblage. Mechanical tests and microstructural observations carried out on non-oriented 3%Si-Fe magnetic sheets showed that the magnetic domain structure is quickly destroyed under 0 to 5% deformation. Correspondinlgy, the dislocation density increases following the experimental law: Log(ρd)=α+βε (α, β = constants). These results are suggested to be related to the magnetic properties alteration due to the sheet forming. (orig.)