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© CADFEM 2017
Vibration and Acoustics for Electric Drive Development
Presenter: Jens Otto, CADFEM GmbH
Developer: Dr. Jürgen Wibbeler, Dr. Martin Hanke , CADFEM GmbH
1
4th CADFEM ANSYS Simulation Conference Ireland & UK
12th and 13th October, Engineers Ireland, Dublin
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 2
© CADFEM 2017
1. Business of CADFEM GmbH
CADFEM in Germany, Austria, Switzerland:
• Founded in 1985
• 2,300 customers
• 11 locations
• 220 employees
(≈ 130 of them technical experts)
BerlinHannover
Dortmund
Chemnitz
Stuttgart
Lausanne
Aadorf
Grafing Wien
InnsbruckZürichOtterfing
FrankfurtDarmstadt
Numerical Prediction of Motor Noise in a Continuous Speed Range 3
© CADFEM 2017
1. Business of CADFEM GmbH
CADFEM – Simulation is more than Software:
• ANSYS Elite Channel Partner
• PRODUCTS
Software und IT Solutions
• SERVICES
Advice, Support, Engineering
• KNOW-HOW
Transfer of Knowledge
Numerical Prediction of Motor Noise in a Continuous Speed Range 4
© CADFEM 2017
1. Business of CADFEM GmbH
CADFEM ANSYS Extensions:
Numerical Prediction of Motor Noise in a Continuous Speed Range 6
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 7
© CADFEM 2017
2. Electrical Drives as Noise Sources
E-mobility
Railway traction
Marine Propulsion
Energy Sector
Industrial Drives
Home Appliances
Universal Motors, …
Wikipedia
Wikipedia
Schottel
Numerical Prediction of Motor Noise in a Continuous Speed Range 8
© CADFEM 2017
2. Electrical Drives as Noise Sources
Origin of Noise by Electrical Drives:
Electric Drive Acoustics inside ANSYS
Magnetic Circuit
Gap forces
Fluidics
Cooling
Drive Side
Gearbox etc.
Reluctance, Geometry
Current Waveform,
Inverters
Magnetic Saturation
Courtesy of Elektromotorenwerk
Grünhain GmbH
Numerical Prediction of Motor Noise in a Continuous Speed Range 9
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 10
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Positioning Noise Analysis (NVH) in a Motor Design Process:
Advanced MagneticsModeling
Maxwell 2D/3D
EfficientMotor Design Toolkit
Motor-CAD Mechanical,
CFDControl Logic, Software
System Validation
Lab
EmagThermal
Lab
NVH, Cooling
Design Analysis Operation
Numerical Prediction of Motor Noise in a Continuous Speed Range 11
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Analysis Workflow:
Electro-
magnetic
Analysis
Harmonic
Vibration
AnalysisDFT
Oscillation,
ERP,
Waterfall PlotExcitation
Loads
External computation
of excitation loads
Numerical Prediction of Motor Noise in a Continuous Speed Range 12
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Waterfall Diagram by Measurement:
• Equipment:
• Accelerometers
• Microphones
• Spectrum analyser
• Anechoic room
• Easy to record at controlled
run-up of a motor
Example traction drive (www.vem-group.com)
Numerical Prediction of Motor Noise in a Continuous Speed Range 13
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Computational Effort for a Waterfall Diagram Produced by Simulation:
Example: 40 rotational speed points
30 spectral lines
= 1200 simulation points!
FEM-methods with minimized
computational effort required for
• electromagnetics
• structural dynamics
One simulation point per rotational
speed and spectral index!
Numerical Prediction of Motor Noise in a Continuous Speed Range 14
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Equivalent Radiated Power (ERP):
• Obtained from structural velocity at
the vibrating surface
(surface normal component vn)
• Natural deviation from true radiation
by σ ≠ 1: Pacoustic = σ·PERP
• Advantage of ERP vs. air-born acoustics:
• No meshing of fluid space computationally less expensive
• Returns a fast figure of produced noise
• Indicates critical operating points efficient comparison of designs
AvcP dˆ2
1 2nERP
15Numerical Prediction of Motor Noise in a Continuous Speed Range
© CADFEM 2017
3. Concept of FEM-based Noise Computation
Utilization of Results:
f
n
ERP [dB]
Identify critical OPsGet vibration shapes
for critical OPs only
Analyse true radiation
by acoustic field
simulation
(optional;
by dedicated tools for
air-borne acoustics)
Numerical Prediction of Motor Noise in a Continuous Speed Range 16
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 17
© CADFEM 2017
4. Computation of Magnetic Excitation Loads
Excitation Loads at Stator (Time Domain):
• Goal:
Forces/moments acting at stator teeth(2D: Frad, Ftan, Mz; 3D: + Fz, Mrad, Mtan)
To be condensed to load centroids
Frad Ftan
Mz
Load
centroid
Maxwell 2D or 3D
Load as function of time:
Numerical Prediction of Motor Noise in a Continuous Speed Range 18
© CADFEM 2017
4. Computation of Magnetic Excitation Loads
Reducing Electromagnetic Simulation Runs:
• Loads vary continuously in characteristic
sections of the operating range.
A few OPs are sufficient to capture
load variation.
Reduce EM-Simulations to selected OPs
• Interpolate loads at intermediate OPs
later at structural simulation.
Internally done by E.D.A. inside ANSYS
Applicable to synchronous motors and
synchronous pulsed inverters
(required fi ~ n)
n2
n1
n3
Interpolation of
excitation loads
OP = operating point
Numerical Prediction of Motor Noise in a Continuous Speed Range 19
© CADFEM 2017
4. Computation of Magnetic Excitation Loads
Data Transfer to Structural Dynamics by Files:
• Export load sets for centroids of faces or face segments into csv-file:
(e.g. for 2D load sets: Time, Frad1, Ftan1, Mz1, Frad2, Ftan2, Mz2, …)
Numerical Prediction of Motor Noise in a Continuous Speed Range 20
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 21
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Workbench Project: Harmonic Analysis Based on Mode Superposition (MSUP)
• Eigenmodes and Eigenfrequencies
as intermediate result
• Faster than full harmonic analysis
• Excitations as input to harmonic analysis
Mode 1 Mode 3 Mode 6
610 Hz 1456 Hz 2654 Hz
Excitations
Modal Analysis Harmon. Analysis
ANSYS Project Structure:
Numerical Prediction of Motor Noise in a Continuous Speed Range 22
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Speed-up at ERP-computation Based on MSUP Harmonic Analysis:
Full Harmonic Analysis
Vibration of structural nodes
ERPComputationally
expensive!
Method used by
E.D.A. inside
ANSYS
MSUP Harmonic
Analysis
Vibration of structural nodes
Complex modal displace-
ments ("modal coordinates")
ERP
Expansion Pass
ERP
Time and memory
saving!
AvcP dˆ2
1 2nERP
Numerical Prediction of Motor Noise in a Continuous Speed Range 23
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Electric Drive Acoustics
inside ANSYS:
• ACT-based Extension
for ANSYS Mechanical
• Appears as a toolbar
in the GUI
Numerical Prediction of Motor Noise in a Continuous Speed Range 24
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Support of Load Import and Application:
• Text based import
interface,
flexible formats
• DFT at import
• Graphical check
• Load application
always
at Remote Points
(= load centroides)
Import preview
Load file table
Numerical Prediction of Motor Noise in a Continuous Speed Range 25
Remote Points
attached to faces
Excitation
loads
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Treatment of Non-skewed and Skewed Motors:
Non-skewed Skewed
Single point per stator tooth Axial discretization of loads
Numerical Prediction of Motor Noise in a Continuous Speed Range 26
© CADFEM 2017
5. Structural Dynamics and Noise Using Electric Drive Acoustics inside ANSYS
Support of Solution and ERP-postprocessing:
Extraction of vibration
shape at selected OP
Definition of sweep parameters
ERP-spectrum at
selected speed point
ERP-waterfall diagram
across speed range
Numerical Prediction of Motor Noise in a Continuous Speed Range 27
© CADFEM 2017
1. Business of CADFEM GmbH
2. Electrical Drives as Noise Sources
3. Concept of FEM-based Noise Computation
4. Computation of Magnetic Excitation Loads
5. Structural Dynamics and Noise using
Electric Drive Acoustics inside ANSYS
6. Summary and Additional Topics
Numerical Prediction of Motor Noise in a Continuous Speed Range 28
© CADFEM 2017
6. Summary and Additional Topics
Summary:
• ANSYS-based tool for efficient assessment of noise induced by magnetics
• ERP Waterfall diagram
• Continuous workflow with easy-to-use functions
• First release in July 2017
www.cadfem.de
Numerical Prediction of Motor Noise in a Continuous Speed Range 29
© CADFEM 2017
6. Summary and Additional Topics
Selection of Additional Topics:
Lamination and coil modeling
r0
r8
0.001
0.01
0.1
1
0 4 8 12 16 20 24 28 32 36 40 44 48
r0
r4
r8
r12
Circular force pattern analysis
Induction motors,
Inverters
Connection to parametrics
and optimization
Numerical Prediction of Motor Noise in a Continuous Speed Range 30