## Definition

Mechanical slot modulation effect, also called tooth sampling effect, refers to the fact that **airgap magnetic stress waves are “sampled” when converted to physical magnetic forces** applied to stator teeth. Consequently, due to Shannon theorem, the maximum stress wavenumber seen by the stator yoke is given by Zs/2 (half the number stator slots).

## Application to e-NVH

This example illustrates in a 12 stator slots and 10 poles Permanent Magnet Synchronous Machines (PMSM) the sampling effect of the fundamental stress wave (r=2p=10) in an equivalent stress wave of wavenumber r=-2:

In EV HEV NVH applications, for instance in a Zs=48 stator slots p=4 pole pairs PMSM, Maxwell stress waves of wavenumber r=11p+p=13p-p=12p=48 (interaction of 11p/13p rotor field harmonic with fundamental field) are experienced as pulsating forces.

## Application to MANATEE

MANATEE software specialized in the e-NVH simulation of electrical machines and noise reduction of electric motors includes slot modulation effects.