3 IntroductionToday, motors are used in many applications close to the user. The noise pollutes the environment of the user. It is a nuisance that must be mitigated.Origin of the noise in motors:Driving electronicTorque ripple on gearsElectromagnetic forces on statorCoilsTo reduce the noise level, a clear identification of the noise and its source is needed.FLUX is connected to vibrational tool
4 How it worksExport magnetic forces computed by FLUX to mechanical CAE tools for vibro-acoustic studies.Flux applications:2D Transient Magnetics3D Transient MagneticsSKEW Transient Magneticsmechanical CAE tools:MSC NASTRAN/ACTRANLMS Virtual.Lab
5 How it works Indirect Method Direct Method PATRAN NASTRAN Virtual.Lab Support for computationPATRANImport :File1.bulkIndirect MethodNASTRANExport: File2.bulkForces on supportCalculation and visualization of magnetic forcesDirect MethodVirtual.LabFile.unvForces and support
6 How it works in FLUXNew function in a new dedicated context Menu [Computation]/[Open mechanical analysis context]
7 How it works in FLUXThe main functions available in this new context are:Creation of new computation support.Computation of the magnetic forces.Results visualizationResults export in multiphysics files to:MSC NASTRAN (.bulk)LMS Virtual.Lab (.unv)
8 Coupling to MSC Nastran GeometryMeshPhysicsSolvingPost-processingAnalysis on one mechanical period + Forces computation + Visualization + Forces exportTransient applicationForces import from FluxVibratory responseGeometryMechanical meshAcoustic response
9 Coupling to MSC Nastran Magnetic pressures: Maxwell tensor Only for the rotating machines. Computed in the air gap. On a circle (2D) or a cylinder (3D et Skew)
10 Coupling to MSC Nastran Vibro-acoustic analysis must be performed on a full mechanical cycle (360°mech).The time sampling and the mesh must be set to take into account:space harmonics.time harmonicsComputation in FLUX can be performed using periodicities. The signal is automatically rebuilt to the full mechanical cycle.Magnetic pressures will be calculated in the airgap, tangential and normal comp.Normal component:Tangential component:
11 Coupling to MSC Nastran StepSoftwareDescription1MSC NASTRANPreparation of the MSC NASTRAN project:Standard description: geometry, physics (The same characteristics with the Flux project) and the mechanical mesh.Export the mechanical mesh as a (.bulk) file which be used in Flux.2FluxPreparation of the Flux project :Geometry, mesh, physics (Transient application) and solving.3During post-processing:Open mechanical analysis context.Import mechanical support built in NASTRANCreate computation support in the air gap.Calculate the magnetic forces on the computation support and project this forces on the nodes of the mechanical support.Visualize the magnetic forces.4Export magnetic forces to MSC NASTRAN as a (.bulk) file5Import the (.bulk) file containing the calculated magnetic forces in Flux and make the vibro-acoustic analysis.
12 Coupling to MSC Nastran Computation support created in MSC, imported in FLUX Cylinder in airgap – coupling only for radial motors (cylindrical airgap) Imported in FLUX (2D, SKEW, 3D)Mechanical SupportComputation SupportSliding CylinderRotor radius
15 Coupling to Virtual.Lab GeometryMeshPhysicsSolvingPost-processingImport of Forces from FluxStructural Model + Modal BasisMapping to Structural Model + Vibration ResponseAcoustic Respons
16 Coupling to Virtual.Lab Magnetic pressures computation:In FLUX: dFmag/dS (already implemented)Computation performed on borders between magnetic regions and air or vacuum regionsThe magnetic pressures are transformed to magnetic forces on each nodes of FLUX mesh.General method not limited to radial machines.
17 Coupling to Virtual.Lab Create the computation support on which the magnetic forces will be calculated.
18 Coupling to Virtual.Lab The computation support is created for the whole geometry even is the periodicity is taken into account. The support will be exported as a 3D support with the corresponding magnetic forces on each nodes.Computation support on the stator teeth
21 Coupling to Virtual.Lab Only the time signal is exported on each nodes of the Flux meshIf Flux 2D is used We must indicate the layer number on the depth of the machine before exporting17N17N1N1N1NMagnetic forces calculated with Flux 2D(Total Forces on the depth )17 layers on 170 mmForces exported as (.unv) file(Indicate the layers number on the depth)
22 Coupling to Virtual.Lab StepSoftwareDescription1FluxPreparation of the Flux project :Standard description : geometry, mesh, physics (Transient application) and solving2In the post-processing:Go to mechanical analysis contextCreate a computation supportCompute magnetic forces on the support.Visualize the magnetic forces3Export the magnetic forces to LMS Virtual.Lab in (.unv) file4LMS Virtual.LabPreparation of the LMS Virtual.Lab project:Geometry 3D: The same geometric dimensions and the same physic characteristics as the Flux project.5Import the (.unv) file containing the computed magnetic forces from Flux.6Structural model + Modal basisMapping of the structural model + Vibratory responseAcoustic response
23 Coupling to Virtual.Lab – A Salient Pole Motor Mechanical PowerMean Value55 kWRotor velocity7500 rpmCurrents in phasesPeak value (sinus wave)70 AField currentConstant value10 A
24 Coupling to Virtual.Lab The UNV file containing the EM Surface Mesh and time domain forces is imported in LMS Virtual.Lab Acoustics The user can inspect the force distribution per time step and animate the forces in time domain
25 Coupling to Virtual.Lab Structural model + Modal basisContains stator, windings, end caps, housing One homogenized but orthotropic material is chosen to model the stator (stiffness) In first instance, a modal basis is used to capture the dynamics of the structure
26 Coupling to Virtual.Lab Forces mapping to structural model + Modal basisLMS Virtual.Lab maps the EM Forces conservatively from the EM surface to the coarser structural mesh surface A Fourier transform provides frequency domain forces These forces are used to compute the vibration response
27 Coupling to Virtual.Lab Acoustic responseLMS Virtual.Lab Acoustics further computes the acoustic radiation:SPLSound PowerDirectivityEnabling technologies ensuring a fast acoustic simulation result: FEM Acoustics, AML (PML technology)The results show clearly the harmonic content (7500 RPM stator teeth freq = 6 kHz, rotor pole freq = 500 Hz) of the forces as well as the modal content of the structure (eg first breathing mode around 3 kHz)
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