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Structural Vibration and Acoustic Analysis of a 3-Phase AC Induction Motor

Peyman Poozesh
Kettering Univ-Allan Taylor, Javad Baqersad
  • Technical Paper
  • 2019-01-1458
To be published on 2019-06-05 by SAE International in United States
This paper is aimed at studying the NVH and acoustic performance of a 3-phase AC induction motor in order to find a way to reduce the magnetic component of noise from an electric motor in an electric vehicle (EV). The method suggested here is to reduce the magnetic component of sound from the motor by making modifications to the end bracket of the motor housing. EVs are being considered the future of mobility mainly owing to the fact that they are environment-friendly. With a lot of companies already investing heavily in this technology, electric drives are set to become extremely popular in the years to come. The heart of an EV is its motor. Modern electric vehicles are quiet and with the lack of an IC engine to mask most sounds from other components, the sound from the electric motor and other auxiliary parts become more prominent. This paper lays down a process to analyze the sound radiated from the electric motor in three broad steps. First, to model the motor in an electromagnetic platform,…

Noise and Vibration End-of-Line Production Testing and Analysis Challenges

Bruel & Kjaer-Chris Moon
  • Technical Paper
  • 2019-01-1464
To be published on 2019-06-05 by SAE International in United States
Theoretical modeling continues to play a larger role in noise and vibration engineering; however, until products are perfectly made, there will be a need to evaluate their end of line (EOL) performance. Manufacturing production of a wide range of items has classically involved some amount of subjective and/or evolved objective quality testing along the line or at the end of the line. This testing can have goals of determining product safety, durability, functionality, or the vibration/sound quality. A vibration-based measurement approach is often used for many of those goals. Often, many modern products utilize some combination of electric motors, internal combustion engines, and power transmission rotational components. The EOL testing for many of these rotational components is after many years now heavily refined in the measurement and analysis methods, and the separation of good, bad and marginally bad samples may not always be challenging. It is frequently the non-standard types of products, either subcomponents or assemblies, which may provide unique challenges to the typical measurement and analysis methods. Additionally, depending on how new the EOL…

Psychoacoustic Order Tonality Calculation

HEAD acoustics GmbH-Julian Becker, Roland Sottek
  • Technical Paper
  • 2019-01-1466
To be published on 2019-06-05 by SAE International in United States
Quantifying tonalities in technical sounds according to human perception is a task of growing importance. The psychoacoustic tonality method, published in the 15th edition of the ECMA-74 standard, is a new method that is capable of calculating the perceived tonality of a signal. Other methods, such as Prominence Ratio or Tone-to-Noise Ratio do not consider several essential psychoacoustic effects. The psychoacoustic tonality is based on a model of human hearing and thus is able to model human perception better than other methods. The algorithm described in ECMA-74 calculates tonality over time and frequency. In practice, tonalities often originate from rotating components, for example, parts of an electric motor. In these cases, quantification of the tonality of orders is often more interesting than the tonality over frequency. In this paper, an extension of the psychoacoustic tonality according to ECMA-74 is presented. With this extension, it is possible to calculate the order tonalities by using the rotational speed characteristics of the measured signal in order to control the parameters of the auditory filter bank. Two of the…

Sound Analysis Method for Warble Noise in Electric Actuators

General Motors-Nathan T. Parker
  • Technical Paper
  • 2019-01-1521
To be published on 2019-06-05 by SAE International in United States
Multiple automotive applications exist for small electric motors that are activated by vehicle occupants for various functions such as window lifts and seat adjusters. For such a motor to be described as high quality, not only should the sound it produces be low in amplitude, but it also needs to be free from pulsations and variations that might occur during its (otherwise) steady-state operation. If a motor’s sound contains pulsations or variations between 2 and 8 cycles per second, the variation is described as warble. Warble noise needs to be measured and quantified in parts and vehicles, such that appropriate limits can be established whereby quality noise performance is conveyed in vehicles. Building on existing Sound Quality metrics such as Loudness and Pitch Variation, a method is established by which processed sound data is further processed via Fourier Analysis as a secondary operation. Thus warble can be reduced to a single value, and in this way, noise engineers have a basis to measure and report warble, and to facilitate product development with A/B comparisons. Depending…

Test and Analysis of Electromagnetic Noise of an Electric Motor in a Pure Electric Car

Geely Automobile Research Institute-Perry Gu, Chao Gong
Geely Automoile Research Institute-Qiang kang
  • Technical Paper
  • 2019-01-1492
To be published on 2019-06-05 by SAE International in United States
Compared with the low-frequency ignition order of mechanical and combustion noise of the internal combustion engine, the electric drive assembly noise of electric vehicles is mainly the high-frequency whining order noise generated by the electromagnetic force and gear meshing, as well as the high-frequency umbrella noise generated by DC/AC pulse width modulation. Although the radiated sound power is far less than that of an internal combustion engine, the high frequency noise of the motor and the reducer is also annoying. In this paper, the main characteristics of the vibration and noise of an electric motor are obtained by testing it on the vehicle and on the test rig. The main frequency orders are multiplies of motor poles, of which the most significant is the 48th order. The deformation of the motor at the resonance frequency of the 48th order is the breathing mode. Through analysis of electromagnetic force wave, the sources of main orders of motor noise are explained. The most significant order 48th comes from the interaction between rotor magnetic field and stator slots.…

Open-access experimental data for NVH benchmarking of e-machines under electromagnetic excitations

EOMYS Engineering-Karine Degrendele, Jean Le Besnerais
L2EP-Emile Devillers, Michel Hecquet
  • Technical Paper
  • 2019-01-1459
To be published on 2019-06-05 by SAE International in United States
This paper presents an experimental setup dedicated to the analysis of acoustic noise and vibrations due to Maxwell magnetic forces in electrical machines, a significant NVH source in hybrid and electric vehicles traction motors. Both electromagnetic excitations and structural response of the electrical machine are simplified to provide the first public benchmark of e-NVH phenomenon (electromagnetic Noise, Vibration, Harshness). The paper first describes how the testbench is designed and tested to reduce as much as possible modelling and experimental uncertainties. A Permanent Magnet Synchronous Machine topology from EV/HEV application is used to illustrate tooth modulation effect and interaction between radial and tangential force-induced vibrations, and designed to generate the resonance of several stator structural modes with simplified electromagnetic loading (open-circuit case). A larger air gap allows the insertion of a fine search-coil network to measure time and space distribution of the air-gap flux density and resulting Maxwell stress harmonics. Accelerometers are placed on stator tooth tips to capture tooth bending motion, as well as on the outer yoke of the stator. Besides vibration measurements, sound…

determination of Vehicle Interior Noise Due to Electro Motor

Univ. of Michigan-Dearborn-John G. Cherng
  • Technical Paper
  • 2019-01-1457
To be published on 2019-06-05 by SAE International in United States
Automotive industry is facing new NVH challenges due to the emergence of hybrid and electric vehicles. In these vehicles, because of the absence of the dominant noise source from internal combustion engine many other sources become unmasked. In addition, new noise sources are generated by the electric powertrain system. One of the important noise sources is the electric motor of the electric powertrain system. The present work is directed towards the application of numerical simulation methods for the evaluation of automotive interior noise due to an electric motor. Specifically, the interior noise of a typical automotive cabin is evaluated numerically. In the first phase, electromagnetic simulation is performed to evaluate the transient (Maxwell) forces on the teeth of the stator of the motor. Subsequently, the forces are transformed to frequency domain and applied to calculate the motor vibration using structural dynamic analysis. These vibrations are mapped to the surface of the motor housing and the radiated noise is computed using acoustic boundary element analysis. In the final phase, the sound power radiated by the electric…

Multiphysics Multi-Objective Optimization for Electric Motor NVH

ANSYS Inc.-Henry Zhang, Yijiang jia
ANSYS, Inc.-Joe Ricci
  • Technical Paper
  • 2019-01-1461
To be published on 2019-06-05 by SAE International in United States
Prediction of noise/vibration at the design stage is important for motor design. However, due to the multiphysics nature of the noise, vibration, harshness (NVH) simulation, an integrated workflow is required for wide adoption across industries [1-5]. ANSYS Workbench provides a platform where electromagnetic, structural and acoustic solvers can communicate with each other without user interventions. Based on the platform, multiple design points can be created with statistical sampling on given design spaces and solved by distributed high performance computers. Response surfaces can then be created with the solution from the design points and used for multi-objective optimization. To demonstrate the optimization workflow, multiple parameters for a motor design similar to the Prius motor are created. Four geometrical variables are selected for optimizing the electromagnetic and acoustic performance of the motor, including the width of slot opening (Slot_Open), the height of the slot opening (Slot_Open_Height), Q-axis flux path width on the rotor (Qaxis_Width), and the thickness of rotor magnetic bridge near the airgap (Flux_Bridge). Equivalent radiated sound power level (ERPL) and torque are calculated. Sensitivity study…

Design of electric motor using coupled electromagnetic and structural analysis and optimization

Altair Engineering-Numair Mazgaonkar, Linus Francis Fernandes
Automotive Accessories-Mazharul Chowdhury
  • Technical Paper
  • 2019-01-0937
To be published on 2019-04-02 by SAE International in United States
Vehicle architecture in existing vehicles is changing continuously due to the need for increasing vehicle electrification. Electric motors have helped sustain this requirement. Traditional internal combustion engines are being replaced or coupled with traction motors or in-wheel motor systems in the full or hybrid electric vehicles. With the use of electric motor in a vehicle, several parts can be reduced. This leads to reduced packaging size and complexity. Also, CO2 emissions are reduced, and overall efficiency is increased. But the task of designing an electric motor which is which assembled in a vehicle could be quite complex. The design of an electric motor can affect the durability, and noise and vibration characteristic of the vehicle structure to which it is connected. The design of the vehicle structure to which the motor attaches should be able sustain the magnetic torque generated by the motor. Electromagnetic forces generated on the stator of an electric motor affect the vibration characteristic of the motor casings and structure to which it connects. In an internal combustion powered vehicle, engines contribute…

Design of an Electric Drive Transmission for a Formula Student Race Car

Gavin White, Geoffrey Cunningham, Darryl Doyle
  • Technical Paper
  • 2019-01-1295
To be published on 2019-04-02 by SAE International in United States
This paper presents a methodology used to configure an electric drive system for a Formula Student car and the detailed design of a transmission for in-hub motor placement. Various options for the size, number and placement of electric motors were considered and a systematic process was undertaken to determine the optimum configuration and type of motor required. The final configuration selected had four 38 kW in-hub motors connected through a 14.8:1 reduction transmission to 10” wheels. Preliminary design of the transmission indicated that the overall gear ratio would be best achieved with a two-stage reduction, and in this work an offset primary spur stage coupled to a planetary second stage was chosen. Detailed design and validation of the transmission was conducted in Ricardo SABR and GEAR, using a duty cycle derived from an existing internal combustion Formula Student car. The analysis was conducted in line with ISO 6336 and permitted the examination of the stresses in gear teeth and the prediction of gear and bearing life. A detailed design was proposed with due regard to…
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