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  • 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 drivers 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

    2

  • eDRIVE NVH PROCESS OVERVIEW

    NVH

    Simula-tion

    System

    Test

    Vehicle

    Test

    Design

    EM

    Simula-tion

    Gear

    Analysis

    3

  • 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

    5

  • 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

    6

  • 7

    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

    8

  • 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

    9

  • 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

    10

  • 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

    11

  • 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

    12

  • SYSTEM TESTS

    13

    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

    14

  • 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

    15

    Acoustic camera

  • SIMULATION RESULT VERIFICATION

    NVH characteristic is predicted correctly

    16

    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

    17

    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

    19