# AC_SCIM_003

### Objectives

Topology SCIM Hybrid permeance / mmf electromagnetic model EM1.SCIM, permeance calculated with FEMMAnalytical structural model [SM.ANLAnalytical acoustic model AC1 Sound pressure level at 1 m in dBA Squirrel cage induction motor

### Machine

The machine SCIM_020 is a squirrel cage induction motor used in naval application (drege pump).

### Results

Simulated sound pressure level of a naval induction motor dredge pump
Measured sound pressure level of a naval induction motor dredge pump

Within a few seconds of calculations, MANATEE software correctly predicts the two main resonances due to magnetic forces, and the sound pressure level (SPL) at 1m away from the machine at resonance is close from measured values in spite of degraded acoustic measurement conditions and unknown damping.

Some differences in the spectrograms are due to PWM, gearbox and aerodynamic noise present in the experiments but not included in this MANATEE simulation, at it was already known that noise was independent of the switching frequency and was therefore more due to slotting harmonics rather than PWM harmonics.

The first resonance is due to slotting harmonics exciting the circumferential mode (4,0) of the stator lamination, the secondary resonance is due to slotting harmonics exciting the mode (0,0) of the stator lamination.

A redesign of this machine gave 15 dB reduction and this reduction was validated with experiments.