Electric Machine NVH Simulation & Accurately Predict Automotive Aeroacoustic Noise [PDF]

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Electric Machine NVH Simulation & Accurately Predict Automotive Aeroacoustic Noise 流程演示

Wayne.Dai / 戴偉修 Joe.Chen / 陳建佑

Many Noise Sources: • Electromagnetic • Stator Tooth Forces • Magnetic Unbalance (UMP) • Inverter Switching Noise • Mechanical • Gears, Bearings • Road Noise • Load variation • Aero-Acoustic • Wind Noise • Fan/Pump/Flow

Affects Product Quality - Real and Perceived Poor NVH = Low Quality

One of Many Req’s: • System Performance • Overall Torque & Power • Efficiency / Fuel Economy • Many Operating Points • Packaging • Volume and Aspect Ratio • Weight • Durability • Stress, Fatigue • Temperature Cycling • NVH • Vibration & Acoustic • Cost • Materials + Engineering + Time

- Noise - Vibration - Harshness

RPM

Electric Machine NVH – What and Why?

Frequency [Hz]

Multiphysics Workflow of Simulation Electromagnetic Field

Structural Dynamics

Sound Experience

Mechanical VRXPERIENCE Sound

Single-RPM ERP Level Multiple-RPM

Maxwell

SPL

Step 1 : 計算定子齒部的受力 磁場計算結果

電磁力分佈

+ 驅動器切換頻率 + 轉子偏心or不對稱的電磁力 + 2Dor3D模擬；分數or全模型

Step 2 : 將電磁力導入Mechanical ∆𝑇 =

Time-Step Definition

Object Based

𝑇𝑒𝑙 𝑁

N - Total number of time-steps within one electrical period/cycle

Maximum Frequency Range 𝐹𝑚𝑎𝑥 =

1 ∆𝑇 ∗ 2

Element Based Advanced Time Window Definition Number of repeated sample windows = 𝑘

Number of cycles/periods (related to force) = 𝑙 Minimum Frequency Range

Step 3 : 結構分析

Static and Modal

Geometry and Meshing • Bolt Pretension • Static Prestress • Modal Analysis (Free Vibration) • Contacts, Joints, Bearings, Coils, Damping

Assembly weight

固定端

Harmonic

ERP vs Frequency and RPM

Multiple Load Sources e.g. Gear Force Spectrum e.g. Fluid Wall Pressure

*ERP = Equivalent Radiated Power

Step 4 : ANSYS Mechanical 模擬結果 • 根據經典電機噪音模擬流程，完成 從Maxwell到Mechanical Acoustics 的模擬工作。 ERP Level

SPL

• 從Harmonic Response分析模組中得到 ERP level waterfall 結果，或從Harmonic Acoustics 分析模組中得到 SPL waterfall 結果 • 右鍵導入 VRXPERIENCE Sound Pro （ export to VRXEPRIENCE Sound Pro）

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Step 5 : 將模擬結果導入 VRXPERIENCE Sound Pro • 打開 VRXPERIENCE Sound Pro 軟體 • 文件/File > /打開/Open 從Mechanical模 組中匯出的模擬結果，通常為 xml 文件

E-motor EPR Demo.xml

• 設定需要創建聲音的長度（ duration ），並設置合適的採樣頻率 （ sampling frequency ）以防止不必要的信號混疊現象 • 點擊合成（ synthesize ），等待聲音的檔的導入生成

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Step 6 : 重播體驗模擬結果 重播控制台 • 使用重播控制台來重播及體 驗創建出來的模擬音效檔 • 如果在播放過程中聲音的音 量過大，軟體會自動開啟保 護模式（Safety mode）將系 統靜音。此時，請手動減小 聲音增益，並點擊 Clipping 和 MUTE 來重置系統 調整聲音增益

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Step 7 : 信號的時頻譜Time – frequency閱覽 • 在時域信號視窗中右鍵 計算時頻瀑布圖 • 使用顯示調整工具（ Color Scale ）來調 整視頻圖的顯示效果

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Step 8 : 心理聲學指標計算 • 重新回到聲音的時域信號視窗 • 點擊 模組/Modules > 心理聲學/Psychoacoustics > 指標/Indicators 啟動心理聲學指標計算介面

• 選擇感興趣的心理聲 學指標及的需要分析 的信號，然後點擊計 算/compute 得到相應 的結果

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Step 9 : 導入傳遞函數 • 重新回到聲音的時域信號窗口，點擊 工具/Tools > 濾波/ Frequency filtering 打開濾波器界面

CABIN_Transfer_Function.csv

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Step 10 : 階次識別及提取

• 在時間-階次顯示窗口中右鍵 導出階次功能（Export the level of some order） • 以8階作爲間隔/step ，100%的 階次帶寬/band，導出8到200 階之間的重要階次 • 文件/File > 導出整車聲音模擬 階次文件/Export orders to Car Sound Simulator file format

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Step 11 : 導入車內氣動及輪胎行駛噪聲 • 文件File > 打開/Open 氣動及行駛 噪聲文件‘Aero_Road_noise.wav’

• 右鍵計算信號的時頻譜/calculate the time-frequency representation

Aero_Road_noise.wav

• 文件/File > 導出整車聲音模擬背景 音/Export noise to Car Sound Simulator file format

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Step 12 : 車內整體聲音品質體驗 電機原始模擬結果

• 點擊 模塊/Modules > 啓動整車聲音模擬工具/Car Sound Simulator Add-in • 選擇原始點擊仿真結果作爲源信號（ source signal ）

導出的整車聲音模擬階次 (8至200階) 導出的整車聲音模擬背景音

• 選擇剛剛導出的整車聲音模擬階次文件作爲階次輸入 （Partials file） • 選擇剛剛導出的整車聲音模擬背景音作爲背景噪聲輸 入（ Noise file ） • 回放體驗車內整體聲音，幷于原始仿真結果進行比較

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回放控制面板

ANSYS VRXPERIENCE Sound Pro 電機聯合模擬流程 VRXPERIENCE Sound 瀑布圖 - CAE 模擬

電機噪音

傳遞函數

背景雜訊

最終整體聲音 O48

O24

混合背景雜訊 Mechanical

考慮系統傳遞函數

Maxwell

體驗完整的聲音環境

隨轉速變化的電機諧回 應雜訊

預測風險

測量 或 CAE

測量 或 CAE

重播子模組雜訊 CAE

CAE

測量 或 CAE

Sound (20 s)

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實際案例 Switch Reluctance Motor ─ NVH Workflow

Background Manufactured SRM

Simulated SRM Design

Hysteresis Control with Asymmetric Bridge SRM Inverter

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Performance Comparison Comparison performed at the knee point of the SRM operation (209 Nm @ 2768rpm)

Remark: Due to “Stranded Coil” assumption the Inductance at the overlapping state between stator and rotor is higher Consequence: • Lower simulated current at Rising-Edge • Higher simulated current at Falling-Edge with slower Zero-Cross condition • Higher simulated flux linkage with higher simulated torque 19

Shared Geometry

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Electromagnetic Force Transfer

Element-Based

Magnetic Flux Density Distribution

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Surface Force Density Distribution

High Switching Frequency Force Resolution Increasing Speed

Multiple-RPM (Speed) Current Profile

Torque Profile

𝐹𝑚𝑎𝑥

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1 = ∆𝑇 ∗ 2

𝐹𝑚𝑖𝑛 =

2 ∗ 𝑆𝑦𝑚𝑚𝑒𝑡𝑟𝑦𝑀𝑢𝑙𝑡𝑖𝑝𝑙𝑖𝑒𝑟 𝑇𝑒𝑙 ∗ 𝑘 ∗ 𝑙 ∗ 2𝑝

∆𝑓 =

𝐹𝑚𝑎𝑥 𝐹𝑚𝑖𝑛

500 rpm - Characteristics

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Rotor Frequency = (RPM/60)*12*Order Stator Frequency = (RPM/60)*18*Order

Note: “LCM = Least Common Multiple”

500 rpm 1st Mode

12th

1500 rpm 7th to 14th Modes

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12th

3 Simulations output R1 • Baseline simulation

R2 • Optimized E-MAG control strategy (Duty)

R2b • Optimized CAD Housing thickness

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• Open Format Spectrum or Waterfall (for each RPM, one spectra)

Generation of Sound Synthesis

From spectrum data to time domain signal (wav sound)

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Generation of Sound Synthesis

Calulation of time-frequency reprensation

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Generation of Sound Synthesis

Switch on RPM-frequency representation

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Generation of Sound Synthesis

Fast listening comparison of sound

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Waterfall Diagram and Sound Spectrum – Noise Detection

Psychoacoustic Indicators Simulated Waterfall Diagram

SPL vs Time

High Level of dB

Sharpness vs Time

1 - Clearly very sharp

2- clearly very loud

High Peak of Sharpness

Due to electromagnetic Forces

Let’s try to reduce level of red zones

Virtual modification

Due to electromagnetic Forces

Simulated Waterfall Diagram

Improvement trial :

SPL vs Time

- 10 dB on the 2 zones

Results : - reduce the peak of loudness - reduce the peak of sharpness - clearly less annoyance

Sharpness vs Time

Multiphysics Workflow of Simulation Electromagnetic Field

Structural Dynamics

Sound Experience

Mechanical VRXPERIENCE Sound

Single-RPM ERP Level Multiple-RPM

Maxwell

SPL

Aeroacoustics Fan Aeroacoustics Simulation Workflow

Aeroacoustics

Receiver Flow

• Sound is generated aerodynamically ‐ Free-space problem, no solid surfaces: Sound generated from turbulence, jet noise ‐ Free-space problem, with solid surfaces: Fan noise, airframe noise, rotor noise, boundary layer noise, cavity noise ‐ Interior problem: duct noise, mufflers, ducted fan noise

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Propagation

Source

• Minimizing noise to meet regulatory standards and human comfort is an important design consideration for all types of rotating machinery

Fan Aeroacoustics Simulation Workflow Ansys Fluent • • •

High-fidelity modeling of fan aerodynamics Direct and integral methods for sound propagation Inbuilt post-processing for aeroacoustics

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Ansys VRXPERIENCE Sound

Shape optimization •

Design of experiments (DOE) and shape optimization integrated in the solving process

• • • •

Signal duration extension Psychoacoustic analysis Sound design Characterization

CFD simulation Operation condition

Geometr y

Mesh

No of blades=8 Mesh Count=8 Million (Hexcore)

RPM = 2000 Time Step = 2e-5 sec Total Simulation time = 1 sec Boundary

Fan

Motor

Rotating Zone

conditions Least-square cell-based Spatial discretization :2nd order to all Momentum– Bounded central differencing

Sliding Zone Pressure outlet 38

CFD Animation- baseline design

Baseline

Modified Mic

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Mic

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Thank You _________

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補充說明 ANSYS VRXPERIENCE Sound

ANSYS VRXPERIENCE Sound ─ 跨平台聲學分析工具 ✓

測試數據分析 测试数据 测试台架 真实环境测量

✓

聲音, 振動, 轉速, 電壓, 溫度, …

VRXPERIENCE Sound

仿真數據回放及分析 MAXWELL 電磁仿真

聲壓級場, 聲壓級瀑布圖, 頻譜圖, ERP, TL, … MECHANICAL

模態分析 諧響應分析

CAE仿真數據和測試數據的聯合分析。 2019 已上線

頻譜圖，時頻分析選取，階次分析，心理聲 FLUENT 計算流體力學仿真 氣動聲學仿真

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學分析，异響診斷，聲音合成。 2020 即將支持

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ANSYS VRXPERIENCE SOUND PRO 基本功能 仿真結果 回放

聲學特性分析 采集. 分析. 編輯.設計. 報告.

回放及分析

心理聲學

3D聲效渲染

階次分析

自動分解

心理聲學指標計算

僅支持雙揚聲器

旋轉機械階次識別

濾波降噪, 特徵聲音 識別分離

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ANSYS VRXPERIENCE Sound 更多模塊及功能 仿真數據與測試數據 聯合分析&聲音設計

3D聲音渲染回放

聲品質開發

高品質聲音重構回放體驗

心理聲學研究&主觀評價

聲音數據采集

虛擬場景交互體驗 3D高品質交互式聲音體驗

虛擬模型仿真

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ANSYS VRXPERIENCE Sound 主要功能特徵 ANSYS VRXPERIENCE Sound 産品特徵

Pro

Premium

噪音振動的分析、回放及編輯

⚫

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旋轉機械階次分析

⚫

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仿真結果快速回放體驗(與ANSYS Mechanical平臺連接)

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基礎心理聲學研究

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主觀聲音感知測試及評價

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産品聲品質評價及分析

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高品質3D空間聲音模擬重現

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爲駕駛模擬提供交互沉浸式的高精度聲音體驗

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高級階次設計及集成 發動機聲浪增强設計及車內快速體驗 電動車主動聲音設計全方位體驗及調試

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