Standard e-NVH Training Program

M1-Electrical machines and drives: fundamentals for mechanical / NVH engineers

Short description:

This part of the training covers the fundamentals of electrical machines for mechanical or vibroacoustic engineers who are not familiar with electrical engineering. Key notions such as electrical machines topologies, torque production and Pulse Width Modulation are covered.

Detailed content:

  • Working principle of electrical machines
    • Torque production
    • DC / AC machine principle
    • Synchronous Vs reluctance torque
  • Magnetic materials
    • BH curve and saturation
    • Flux, mmf, reluctance
  • Electrical machine manufacturing principles
    • Torque control with DQ frame
    • Speed control with PWM

M2-Sound and vibrations: fundamentals for electrical engineers

Short description:

This part the training covers the fundamentals of acoustic noise and vibrations for electrical engineers who are not familiar with mechanical / vibroacoustic engineering. Key notions such as vibrations, structural modes and resonance, sound pressure / power, A-weighting and sound quality are covered. The link with electrical machines is regularly done during the course.

Detailed content:

  • Vibrations
    • Linear resonator case
    • Stiffness & mass, damping
    • Forced & resonance regimes
    • Generalization to N degrees of freedom
    • Structural modes
    • Modal superposition principle
  • Sound
    • Pressure, velocity
    • Power, intensity
    • Log scale
    • Third octave analysis, dBA
    • Radiation efficiency
    • Distance & reflection effects
    • Sound quality

M3-Generation process of magnetic noise and vibrations

Short description:

This part the training reviews the physical generation process of magnetic noise and vibrations. Key notions such as magnetic force shapes, resonance effects, and air-borne / structure-borne transfer paths are covered.

Detailed content:

  • Magnetic forces in electrical machines
    • Maxwell forces and Laplace forces
    • Magnetostriction
    • Illustration with tuning fork and rotating magnet
    • Notion of wavenumber – rotating and pulsating forces
    • Lumped tooth forces
    • Global forces – torque, UMP, moments
  • Static effect of magnetic forces
    • Radial and tangential forces on outer stator
    • Radial and tangential forces on inner rotor
  • Structural modes of electrical machines
    • Stator modes
    • Rotor modes
  • Dynamic effects of magnetic forces
    • Principle of resonance
    • Application to stator / rotor modes
    • Generalization with modal force
  • Transfer paths of magnetic noise and vibrations

M4-Frequency signature of magnetic excitations including faults

Short description:

This part of the training explains analytically why magnetic force harmonics appear at some specific frequencies and wavenumbers depending on topology and slot/pole combination. General formula of magnetic force harmonics in Permanent Magnet Synchronous Machines and Induction Machines are provided by combining permeance, magnetomotive force, and flux density harmonics step by step.

Detailed content:

  • Slotting harmonics in PMSM
    • Fundamental force
    • Pulsating forces
    • Lowest wavenumber forces
    • Generalization
  • Slotting harmonics in IM
    • Fundamental force
    • Pulsating forces
    • Lowest wavenumber forces
    • Generalization
  • Switching harmonics
  • Effect of faults and tolerances
    • Dynamic and static eccentricities
    • Uneven airgap

M5-Reduction techniques of magnetic noise and vibrations

Short description:

This part of the training reviews some key design rules allowing to control noise & vibrations due to magnetic forces, with their advantages and drawbacks. Noise mitigation techniques cover magnetic, control and structural design parameters, but most of the course deals with electromagnetic design modifications as it is the most efficient way to control magnetic noise and vibrations. Key design parameters for Permanent Magnet Synchronous Machines and Induction Machines are summarized.

Detailed content:

  • Noise control strategies
  • Electromagnetic design
    • Topology – ranking of main topologies
    • Slot / pole / phase numbers
    • Asymmetries
    • Winding design
    • Skewing
    • Pole shaping
    • Slot shaping
    • Notching
  • Control & switching strategy design
    • Current angle
    • Current injection
    • PWM strategy
  • Structural design
    • Yoke shape
    • Frame to lamination contact
    • Damping
    • Transfer paths - airborne Vs structure-borne
  • Synthesis of low noise electric motor design parameters

M6-Numerical simulation of magnetic noise and vibrations

Short description:

This part of the training discusses the different ways to include the assessment of magnetic noise and vibrations in a virtual prototyping workflow of e-machines in terms of accuracy, speed and robustness. Different modelling approaches are reviewed, and numerical challenges of CAE-based calculations are discussed. Algorithms to speed up calculations like vibration synthesis and load extrapolation are presented.

Detailed content:

  • Modelling approaches
  • Electromagnetic calculations
    • Analytical methods (e.g. permeance / mmf)
    • Semi-analytical methods (e.g. subdomain models)
    • Finite element methods
  • Magnetic force calculation
    • Maxwell stress method
    • Virtual work method
    • Equivalent forces
  • Structural calculation
    • Yoke shape
    • Finite element methods
  • Electromagnetic to structural coupling methods
  • Acoustic calculations
    • ERP
    • Semi analytic
    • BEM/FEM
  • Numerical challenges
  • Load calculation algorithms
  • Vibration synthesis algorithm

M7-Experimental characterization of magnetic noise and vibrations

Short description:

This part of the training demonstrates how to carry noise and vibration measurements to quickly troubleshoot issues. Some specific tests are recommended on Permanent Magnet Synchronous Machines and Induction Machines. Some experimental spectrogram coming from EV HEV applications are reviewed in detail and interpreted using theory.

Detailed content:

  • Experimental Modal Analysis / Operational Modal Analysis
  • Operational Deflection Shapes
  • Run-ups, spectrograms, Order Tracking analysis
  • Spatiograms
  • Vibro-acoustic type tests for PMSM and IM
  • Source discrimination methodology
  • Review of EV HEV spectrogram examples