4. Silent design rules

To reduce the magnetic noise radiated by the machine from the design phase onwards, three main approaches are possible:

• act on the amplitude of the excitation alone (weak tooth lines, weak MLI lines, high spatial orders, etc.);

• act on the amplitude of the response alone (low radiation from the structure) ;

• act on the interaction between the exciting force and the excited structure (distance between exciting frequencies and natural frequencies).

The design parameters with the greatest influence on noise are the number and shape of slots, general motor dimensions (outside diameter, yoke height, iron length, air gap)