Spectral analysis of electromagnetic vibrations in DC machines through the finite element method

The authors describe the FLUXMECA software package for calculating the mechanical transfer function of electrical machines, either static or with moving parts, for applied currents of any waveform. The solution method is based on magnetic sampling in space and time and on mechanical analysis in frequency space. The magnetic field is computed by the classical finite-element method for static machines coupled with the boundary integral method for machines with moving parts in order to take movement into account. Mechanical computations are performed by the finite-element method. The calculation of excitation forces, which uses a surface distribution of the local force density on ferromagnetic materials, leads to a correct determination of the resulting mechanical response of the structure. Consequently, the determination of the Fourier spectrum is quite easy even if it requires a large volume of data to take into account the movement of the rotor and its shaft