Combined Analytical–Numerical Noise Calculation of Electrical Machines Considering Nonsinusoidal Mode Shapes

This paper describes a calculation method for the electromagnetically excited noise of different types of rotating electrical machines. A numerically gained modal matrix of the stator is used for the analytical calculation of the surface´s deflection and thus combines short calculation times of analytical methods with the accuracy of numerical calculations. Considering elliptic deformations due to nonsymmetrical pairs of eigenvectors, as especially occurring for small machines with few teeth, a time-stepping algorithm allows the examination of noncircular spatial harmonics of the deformation. An adapted analytical sound pressure calculation is appended. Finally, a comparison with a measurement of the surface oscillation validates the improved calculation method.