NVH Development

Process for eDrive

Systems

Dr. Oliver Grieshofer,

Manager, Dynamics / Acoustics,

Magna Powertrain

NVH DEVELOPMENT PROCESS FOR eDRIVE SYSTEMS

• Acoustic challenges for eDrivedevelopment to fulfill OEM and driver’s expectation

• NVH has to be considered from the early development phase

• All major influences have to be included

NVH development process from concept design to vehicle integration was established

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eDRIVE NVH PROCESS OVERVIEW

NVH

Simula-tion

System

Test

Vehicle

Test

Design

EM

Simula-tion

Gear

Analysis

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eDRIVE NVH PROCESS OVERVIEW

4

NVH

Simula-tion

System

Test

Vehicle

Test

Design

EM

Simula-tion

Gear

Analysis

CHALLENGES FOR eDRIVE NVH SIMULATION

• Excitation mechanisms from magnetic forces and gear

interaction to be considered

• High excitation orders and rotational speed lead to high

excitation frequencies

• ICE 4-cyl: 2nd order * 6,000 rpm = 200 Hz

• eDrive: 82nd order * 15,000 rpm = 20,500 Hz

• Modal reduction of model up to high frequency

large number of modes

• eMotor, gearbox and inverter are a coupled structure

NVH evaluation of system

• NVH assessment of structure and air-borne path

complete surface to be evaluated

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SIMULATION PROCESS

FE-model

Gear analysis

EMAG analysis

•MNOISE gear run-up

simulation of meshing

forces

•Transform forces to

frequency domain for

rpm steps

•Define evaluation

surfaces

•Collect all simulation

results: gear and

EMAG

•Post processing

•Surface noise

•Structure points

FE modal

response

analysis

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GEAR DESIGN FOR NVH

Macro GeometryExcitation orders

Contact ratios

Micro GeometryTransmission errorMeshing stiffness

Stiffnessmatrix from

FEA

Loads

EM

excitation

orders

Package

... andmanymore

MNOISE GEAR

• MNOISE gear analysis

• Input from gear design

• general gear data

• non-linear meshing stiffness curve in operation point

• Time domain run-up simulation with multi-body model

• Evaluation of meshing forces

Tin

nout

Angle

Stiffness

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FE-MODEL OF eDRIVE

Complex FE-model of eDrive

• Inner parts like shafts, bearings and wheels included

• Inverter housing without detailed electronics

• Test rig boundaries necessary for validation, e.g. mounts, side shafts

• Modal reduction: 1,000 < modes

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MNOISE NVH RESULTS

• MNOISE post-processing

• Collect all simulation results

• Campbell of run-up: surface or single point results

• Evaluation method examples

Order cutevaluate noise level and vibration of main orders

Speed cutat defined rpm identify main contributing frequencies

Frequency intervalinvestigation of resonance phenomena

Speed cut

Order cut

Frequency integral

Speed

Fre

qu

en

cy

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MNOISE NVH RESULTS

MNOISE post-processing

• Order cutmain contributing panels can be identified

• Frequency intervalfind surface area with highest noise level

• Animate operational deflection shape to find reinforcement potential

output shaft rpm300 900 1500

No

ise

leve

l

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Frequency

Nois

e leve

l

5dB

NVH IMPROVEMENT EXAMPLE

NVH improvement example

• MNOISE analysis of base design showed noise peak

• Gear box cover had main contribution

• Structural weakness identified –reinforcement ribs added

• Peak was eliminated in MNOISE analysis of new design

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SYSTEM TESTS

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NVH

Simula-tion

System

Test

Vehicle

Test

Design

EM

Simula-tion

Gear

Analysis

eDRIVE NVH TEST RIG

Test rig requirements

• Modular design for different eDrive concepts

• Dynamic stiff structure to minimize influence

• Easy access and handling

• For validation of simulation, rig model included in NVH analysis

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TEST BENCH SETUP

• Flexible semi-anechoic test cell

• Full acoustic housing of secondary brake

• Acoustic camera to find

hot spots

• Microphones at inverter

nearfield and standard

1m positions

• Accelerometers

active/passive side

mount positions to

check isolation

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Acoustic camera

SIMULATION RESULT VERIFICATION

NVH characteristic is predicted correctly

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Surface sound pressure (dBA) 1m sound pressure (dBA)

Intermediate shaft speed (1/min)

1000 2000 3000 4000 1000 2000 3000 4000

1000

2000

3000

4000

5000

Fre

quency

(Hz)

VEHICLE TESTS

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NVH

Simula-tion

System

Test

Vehicle

Test

Design

EM

Simula-tion

Gear

Analysis

NVH DEVELOPMENT PROCESS FOR eDRIVE SYSTEMS

Summary and conclusion

• NVH development process for eDrives established

• Applicable for 48V and high voltage systems

• Acoustic improvement before prototype

• Verified acoustic simulation results

• Reach component target in cooperation with OEM

• Fulfill end customer expectation for successful cars

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