noise reduction of the motor performing nvh analysis

Noise reduction of the motorperforming NVH analysis

Yassine Salhi-Flux Application Engineer EMEA

© 2016 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

Electric Machine Design Process

Specifications

Thermal analysis Flux2D

Advanced Thermal analysis

AcuSolve

NVHOptiStruct

OptimzationHyperStudy

Analytical computations

Compose

Motor topology selection & fast analysis

FluxMotor

Refined design Flux2D / 3D

Prototype & tests System Analysis – SolidThinking Activate

Multiphysics

Control implementation -SolidThinking Embed

2


Summary

• What is NVH analysis?

• Steps and results in Flux

• Steps and results in Optistruct

3


What is NVH analysis?

4



• From electric excitation … to noise• electric energy creates the electromagnetic field that generates the torque• It also generates parasitic forces at the iron/air interface

• Parasitic forces generating noise depend on:• the type and topology of the machine• the electric excitation frequencies

Magnetic torque

5


Why NVH analysis?

• Adapting the control strategy• Adjusting the electric excitation frequency• While maintaining the performance of the machine

• Modifying the shapes of the rotor and the stator

• Optimizing the mechanical structure of the machine

• Designers need specific tools and methods in the early stage of the design:

Coupled electromagnetic vibro-acoustic analysis

6


Why NVH analysis?

Chaining 3 types of analysisMagnetic forces Displacements Noise

Magnetic Vibration Acoustic

7



Electric excitation Magnetic pressure Dynamic response

Magnetic model(2D/3D)

Use of symetries and periodicities

Mechanical dynamic model (3D)

Projectionon mechanical mesh

Electric model (1D)

Strong Coupling

Transient analysis Harmonic analysis8


Steps and results in Flux

9


Steps and results in Flux softwares

• Motor used for the analysis

10



• Steps in Flux

11

• Create materials• Create circuit• Create mechanical sets• Define regions• Define scenario

From the overlay • Compute forces in the mechanical context



12


• Creating of the support


13


• Computations on a quarter of the mechanical period in a eighth of the machine


14



• Force arrows on teeth

15



• Harmonic force arrows : rank 8 and 48

16


Steps and results in OptiStruct

17


NVH analysis

Geometry Mesh Physics Solving Post-processing

Mechanical mesh Vibratory response

Acoustic response

Analysis on one mechanical period + Forces computation + Visualization + Forces exportTransient application

Forces import from FluxGeometry

OptiStruct18


NVH analysis

19

• Step to setup the NVH analysis, we can use this workflow :

1. Mesh the parts 2. Add properties material3. Import the forces from Flux4. Add the ERP output5. Execute the frequency response analysis and post process the radiated surfaces6. Optional : Use the optimization capabilities to reduce the noise of electric machines

Geometry Mechanicalmesh

Forces import from

FluxNVH

analysis ERP output


NVH analysis

• The geometry has been created with Flux 3D


Forces import from

FluxNVH

analysis ERP output

20


NVH analysis

21

• Mesh description :• Isotropic material• Number of elements = 366 480• DOF = 0.7 millions


Forces import from

FluxNVH

analysis ERP output


NVH analysis

22

• Mechanical excitation• Radial Excitation Loads• Tangential Excitation Loads

• The excitation are directly exported to the OptiStruct format from the Flux analysis

• These forces are imported as an include file


Forces import from

FluxNVH

analysis ERP output

Master file : Mesh

Properties / MaterialSubcase definition

Include file from Flux :Excitation / Forces


NVH analysis

23


Forces import from

FluxNVH

analysis ERP output

• Support imported in Flux


NVH analysis

24


NVH analysis

25

Nonlinear Effects:• Bolt Pretension Effect taken into consideration• Contacts defined between the stator, Casing and the bolts


Forces import from

FluxNVH

analysis ERP output

Contact Surfaces


NVH analysis

26

• Preloaded Normal Mode Analysis :• Free-free modal analysis between 0 – 15 000 Hz


Forces import from

FluxNVH

analysis ERP output

First mode at 710 Hz 9th mode at 1905 Hz


NVH analysis

27

• Preloaded Frequency Response Analysis :• 4736 nodes are excited from the Flux analysis between 0 and 7,665 Hz• Constant damping of 5% was defined


Forces import from

FluxNVH

analysis ERP output


NVH analysis

28

• Frequency Response analysis :• ERP (Equivalent Radiated Power) output

• Minimize ERP Reduction of noise and vibrations

• ERP Mathematical Expression


Forces import from

FluxNVH

analysis ERP output

𝐸𝐸𝐸𝐸𝐸𝐸 = 𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 ∗12𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 ∗ 𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 �

𝑖𝑖

𝑛𝑛𝑛𝑛𝑛𝑛𝑖𝑖𝑛𝑛

𝐴𝐴𝑖𝑖 ∗ 𝑣𝑣𝑖𝑖2

ERP evaluation(outer surface of the casing)

• ERPC : the speed of sound• ERPRHO : fluid density• ERPRLF : radiation loss


NVH analysis

29

• Frequency Response analysis :• ERP result


Forces import from

FluxNVH

analysis ERP output


Conclusion

30


Conclusion

31

• The coupling between Flux and OptiStruct allows to study the noise made by an electric machine

• Flux is able to export the excited load in an OptiStruct format The import in HyperMesh is direct

• To go further : Presentation given by Dr Diana Mavrudieva on Wednesday afternoon :Multi-physics Noise Optimization in Fuel PumpPermanent Magnet Motor

Geometry MeshElectro-

magneticanalysis

Forces import

from FluxNVH

analysisERP

output

HyperStudy

Flux OptiStruct


Thank you !

32

noise reduction of the motor performing nvh analysis

Documents