6. Conclusion

Although magnetic noise is a phenomenon that has been known and studied since the 1940s, it is sufficiently complex that few general rules for quiet design can be established. In many cases, numerical simulation of the motor's vibro-acoustic behavior is indispensable to ensure that noise levels remain tolerable.

What's more, minimizing magnetic noise often runs counter to other electrical, thermal or mechanical design objectives: for example, enlarging the air gap reduces magnetic noise, but significantly...