Vibro‐acoustics Analysis for noise reduction of electric machines
Example: Synchronous Machine – Flux 2D Coupling to ANSYS
Farid ZIDAT
Hamza ENNASSIRI
27/08/2015
Introduction  Goal : How to decrease the noise in rotating machine ?
 Origin of the noise in rotating machine
 Driving electronic
 Torque ripple on gears
 Electromagnetic forces on stator
g
 The purpose of this presentation is to show the different steps of the vibro‐
acoustic study of a rotating machines with the new coupling between Flux 2D/3D and ANSYS
and ANSYS
 Firstly we present the main steps to model the rotating machine in Flux 2D/3D
 Thereafter we present the new vibro‐acoustic coupling in Flux
p
p g
 Finally we present the main steps to make vibro‐acoustic analysis in ANSYS
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Main Steps
Geometry
Mesh
Import of Forces
from Flux
Physics
Structural Model +
Modal Basis
Solving
Post-processing
Mapping to Structural Model
+ Vibration Response
Acoustic Respons
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Synchronous machine to model ‐ Presentation
 Targeted performances
Mechanical Power
Mean Value
55 kW
Rotor velocity 7500 rpm
Currents in phases
Peak value (sinus wave)
70 A
Field current
Constant value
10 A
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Main Steps in Flux
Geometry
Mesh
Physics
Solving
Postprocessing
 The geometry is built with Flux overlays
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Main Steps in Flux
Geometry
Mesh
Physics
Solving
Postprocessing
 The geometry is ready to be meshed when we use Flux Overlays
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Main Steps in Flux
Geometry
Mesh
Physics
Solving
Postprocessing
p
g
 In this section we make the following steps:




Create materials
C
t
t i l
Create circuit
Create mechanical sets
Define the different regions of the device
Define the different regions of the device
 A Python file was prepared with the different quantities mentioned above. These
quantities will be created automatically
quantities will be created automatically
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Main Steps in Flux
Geometry
Mesh
Physics
Solving
Postp
processing
g
 Create scenario and solve
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Main Steps in Flux
Geometry
Mesh
Physics
Solving
Postp
processing
g
 Create computation support
 Compute the magnetic forces and their harmonics on this computation supportt
 Display magnetic forces and their harmonics
 Export the calculated magnetic forces to ANSYS
Export the calculated magnetic forces to ANSYS
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Force calculation – Stator Teeth Support Creating Geometry
Mesh
Physics
Solving
 1st: go to mechanical analysis context
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Postprocessing
Force calculation – Stator Teeth Support Creating Geometry
Mesh
Physics
Solving
 2nd: creating stator teeth support to calculate magnetic forces
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Postprocessing
Force calculation – Stator Teeth Support Creating Geometry
Mesh
Physics
Solving
 2nd: creating stator teeth support to calculate magnetic forces
Stator teeth support
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Postprocessing
Force Calculation – Launching the Force Calculation on the Created Support
 3rd: launch the calculation
Geometry
Mesh
Physics
Solving
 The calculation must be launched on one mechanical period
 In Flux we can choose just ¼ of this mechanical period I Fl
h
j ¼ f hi
h i l
i d
 In our case the time interval corresponding to ¼ of mechanical period is:
 [7.33334E‐3 s; 9.33333E‐3 s]  [330°, 420°] 21/10/2015
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Postprocessing
Force Calculation – Launching the Force Calculation on the Created Support
 3rd: launch the calculation
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Force Calculation – Show the Magnetic Forces
 4th: Show the forces to Harmonic 4
Geometry
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Mesh
Physics
Solving
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Postprocessing
Force Calculation – Export Magnetic Forces
Geometry
Mesh
Physics
Solving
 5th: Export forces in txt file, this file will be used by ANSYS.  Exporting procedure From Flux 2D to UNV file 
Exporting procedure From Flux 2D to UNV file  Must indicate the number of Must indicate the number of
layers on the depth of the machine
17N
17N
1N
1N 1N
17 Layers on 170 mm
Forces calculated in Flux 2D
(The total forces on the depth )
Forces exported in UNV file
(We must indicate the number of
layers on the depth )
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Postprocessing
Performing a coupled electromagnetic‐vibro‐acoustic analysis
Step 1: computation of the magnetic induction in the air gap Step 2 : Calculation of the electromagnetic forces on the stator core inner radius
core inner radius Step 3 : Structural dynamic displacements calculation Step 3 : Structural
displacements calculation
Step 4 : Acoustic pressure in the air surrounding the machine
Vibro-acoustic coupling to ANSYS
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Principals of vibro‐acoustic analysis
A
A coupled acoustic
coupled acoustic‐structural
structural interaction analysis takes the structural interaction analysis takes the structural
dynamics equation into account.
 Linearized Navier‐Stokes equations of fluid momentum.
 Flow continuity equation.  In
In acoustic
acoustic‐structural
structural interaction application, the program solves for the fully interaction application, the program solves for the fully
coupled finite element dynamic matrix equation:
[MS] : the mass matrix [MS]
: the mass matrix
[CS] : the damping matrix
[KS] : the stiffness matrix
{fS} : the external force vector in the structure
[ ] h
[R] : the coupled matrix and represents the coupling conditions on the interface between
l d
d
h
l
d
h
f
b
the acoustic fluid and the structure
Vibro-acoustic coupling to ANSYS
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The principal steps for a vibro‐acoustic analysis
 Build the model
 Set up the model environment
 Define material properties
 Mesh
Mesh the model
the model
 Define the boundary conditions  Define the loads and excitations
General process for an acoustic
analysis
 Account for the FSI effect A
t f th FSI ff t
 Solve the model
 Post‐process the acoustic analysis Vibro-acoustic coupling to ANSYS
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Starting the vibro‐acoustic project
 Starting the analysis by indicating the project directory file
 The Global directory folder must contain the “Loads” folder in which the DAT file must be placed Global Project Directory Folder
Directory Folder
Loads folder where the “DAT” file must b l d
be placed
Vibro-acoustic coupling to ANSYS
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Building the model (geometry sharing)
2D – 3D geometry
export from Flux
Importing the
geometry into Ansys
Vibro-acoustic coupling to ANSYS
volumes conversion to a binary structure using the ANSYS Design modeler 21/10/2015
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Import of Forces from Flux using the coupling macro
Macro execution
DAT file from Flux force
calculation
Graphical interface of the coupling Macro
Vibro-acoustic coupling to ANSYS
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Materials affectation to the different elements of the structure
Exploded view of the machine modeled with ANSYS®.
Exploded
view of the machine modeled with ANSYS®
From left to right: End‐bell, windings with end‐connections, stator core ,frame, end‐bell.
Parameters
Ex (Gpa)
Ey (GPa)
Ez(GPa)
Gxy (GPa)
Gxz (GPa)
Gyz (GPa)
νxyz
ρ (kg/m3)
Air volumes surrounding the Ai
l
di th
structure to ensure the FSI Laminations
200
Windings
9.4
Frame
71
200
9.4
71
0.8
9.4
71
79.3
3.5
26.7
0.3
3.5
26.7
0.3
3.5
26.7
0.3
0.35
0.33
7700
8890
2700
Air sphere surrounding the Air
sphere surrounding the
structure to ensure the ABC Mechanical properties of the different Mechanical
properties of the different
structure elements
Vibro-acoustic coupling to ANSYS
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M hi
Meshing the structure h
 Meshing structural elements
Windings
Frame
Stator core
End‐bell
End windings
 Meshing fluid elements
Spherical air layer with absorbing boundary conditions
boundary conditions (ABC) on the external sphere radius cylindrical air layer ensuring the Fluid Structure Interaction (FSI)
Vibro-acoustic coupling to ANSYS
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Performing a modal analysis
Circumferential mode (2,0 at f= 463.2646 Hz) Vibro-acoustic coupling to ANSYS
Circumferential mode (3,0 at f= 1189.0431 Hz) 21/10/2015
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Import of Forces from Flux using the coupling macro
Node creation and nodal forces affectation case of one slice
Vibro-acoustic coupling to ANSYS
Node creation and nodal forces affectation case of multiple slices
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Import of Forces from Flux using the coupling macro
Transfer loads to the elements of the mechanical mesh (case of one slice)
Vibro-acoustic coupling to ANSYS
Transfer loads to the elements of the mechanical mesh (case of multiple slice)
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Transient structural analysis using time varying loads
Vibro-acoustic coupling to ANSYS
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Transient acoustic‐structural analysis
Vibro-acoustic coupling to ANSYS
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The coupling method interest  Classical method
Pressure computation on nodes
Create faces Calculate the mean pressure for each surface C l l
h
f
h f
A complicated process creating nodes, lines, faces then applying loads 2D circular path for electromagnetic forces computation
Applying loads on tooth faces
Nodal electromagnetic forces computation
Applying nodal loads
 Improved method
Force computation on nodes
Create nodes
Create nodes
Apply loads
A simple coupling method more efficient and works For different electrical machines structures Vibro-acoustic coupling to ANSYS
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Conclusion  Vibro‐acoustics analysis for noise reduction of electric machines
 An efficient process using expert tools
 A proven methodology offering convincing results in a reasonable computation A
h d l
ff i
i i
l i
bl
i
time
 Embedded dedicated tools in Flux
 Available in Flux 2D, 3D and skew
 Including fast & easy geometry creation & mesh thanks to motor overlays
 Direct connection to ANSYS  For vibrations & accoustic performance evaluation
 Strong support & efficient consulting services offered by CEDRAT
Strong support & efficient consulting services offered by CEDRAT
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