An iron core impedance model for calculating high frequency common mode currents and shaft voltages in inverter-fed AC machines

In order to calculate the common mode currents and induced shaft voltages in the inverter fed AC machines, a 2D finite element (FE) common mode impedance model of the laminated iron core, assuming the rotational symmetry and the uniform radial current distribution in the lamination sheets, has been proposed in the literature. In this paper, as an alternative to the existent 2D FEM models, a 3D FEM model of the iron laminated core is proposed to calculate the iron core impedance per phase. The proposed 3D FEM model considers better the radial distribution of the common mode current in the stator lamination sheets. The iron core impedance per phase is used to calculate the peak values of the most significant harmonics of the common mode current and of the induced shaft voltage.