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Coupled analysis of motor to predict vibration and noise

By

Mr. Siddesh S Application Engineer

ProSIM R&D Pvt. Ltd.

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Agenda

1. Source of noise in motors

2. Generation mechanism of electromagnetic noise

3. Causes of electromagnetic force in motor

4. Noise reduction techniques

5. Coupled electromagnetic and structural analysis in JMAG

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Noise sources Aerodynamic

Mechanical

Electromagnetic

Self

Load induced

Auxiliaries

Non-uniform air gap

Bearing

Balancing

Source of noise in motors

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Fundamental flux is superimposed with harmonics fields. MMF wave in the air gap causes attractive force and

tangential forces on stator core and teeth due to zigzag leakage permeance.

MMF distribution Magnetic flux wave distribution Electromagnetic force distibution

Generation mechanism of electromagnetic noise

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Electromagnetic force due to eccentricity

Distorted flux density

Causes of electromagnetic forces in Motor

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Skewing Rotor and stator slot shape Stator stack dimension Eccentricity

Manufacturing errors: tolerances, asymmetries

Materials

Noise reduction techniques

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It is important to know the frequencies at which the radial forces are produced and estimation of amplitude of radial magnetic

forces.

Magnetomotive force

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Coupled electromagnetic and structural analysis in JMAG

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Structure of motor 2D Electromagnetic model

Electromagnetic force modeling

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Material specification

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Electromagnetic flux density distribution

Magnetic flux density distribution

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Electromagnetic force distribution Frequency component of electromagnetic force

Electromagnetic force distribution

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Constraint

Rotor mass

Rigid body

Rigid body

0.44kg Rotor mass

Boundary conditions for structural model

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Eigen mode deformation approximately at 3600 Hz

Eigen mode analysis

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Acceleration distribution at 3600Hz

100mm

Sound pressure level distribution at 3600Hz

Structural analysis

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Conclusion

1. The electrical model, which accounts for the influence of mmf space harmonics and determines the air-gap radial

flux density, has been successfully analysed with FEM.

2. Numerical simulation allows in particular to virtually isolate the different sources of noise harmonics: winding

harmonics can be cancelled by imposing sinusoidal mmfs, PWM harmonics can be removed by imposing sinusoidal

currents, saturation harmonics by cancelling saturation permeance harmonics, slotting harmonics by imposing a

smooth air-gap, etc.

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THANK YOU