In Manatee software, the electromagnetic excitations due to Maxwell forces are linearly decomposed into Load Cases. To do so, magnetic excitations are generally expanded in Fourier series along the airgap (for Maxwell stress) or along tooth distribution, resulting in a certain number of wavenumbers.
A magnetic Load Case is defined by four characteristics:
- its type (force or moment)
- its direction of application (radial, circumferential, axial for forces)
- its structure of application (rotor, stator)
- its wavenumber (r=0, r=1, r=2, etc)
Application to e-NVH
Most important Load Case for air-borne magnetic noise are generally radial forces applied to the external structure (stator most of the time) with “low” wavenumbers (r=0, r=1, r=2 for instance).
Most important Load Cases for structure-borne magnetic noise are generally rotor torque ripple (r=0, tangential) and Unbalanced Mangetic Pull (r=1, radial).
For more information, see our technical note on the main transfer paths of magnetic noise and vibrations.
Application to Manatee
In Manatee software, Electromagnetic Vibration Synthesis algorithm naturally calculates the contribution of each Load Case to vibration and acoustic noise levels. This way, a first understanding of the origin of noise issues can be carried at the end of the calculation.