Vibration Analysis / Sound pressure analysis
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138 - Vibration Analysis of an SR Motor
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Module:DS,DP |
2011-07-12 |
SR motors are utilized because they have a simple construction that doesn't
use permanent magnets making them robust yet inexpensive when compared
to other motors.However, the electromagnetic force produced by the saliency
of the stator and rotor cause vibrations and noise.This example presents
the use of a coupled magnetic field and structural analysis to obtain the
electromagnetic force of the SR motor and the resonance of the eigenfrequency
in the stator core.
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114 - Vibration Analysis of an Outer Rotor Motor
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Module:DS,DP |
2011-07-12 |
An outer rotor motor has a magnetic rotor that rotates around a stator.
An outer rotor motor can produce a larger amount of torque than an inner
rotor motor with the same diameter because the radius of the outer rotor
is larger.Vibrations produced by electromagnetic force can be produced
as the motor rotates. The fabrication of the motor can be modified, such
as adding and fabricating holes in the rotor core to change the eigenfrequency
reducing the amount of electromagnetic vibrations that can cause noise
or damage the motor.This example presentsthe use of a magnetic field analysis
and structural analysis to obtain the sound pressure caused by electromagnetic
vibrations in an outer rotor motor with holes fabricated in the rotor core.
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97 - Sound Pressure Analysis of a Transformer
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Module:FQ,DS |
2011-07-12 |
In recent years, the demand to reduce the vibration and noise while improving
the efficiency of transformers is increasing with the demand for environmental
conservation, such as energy conservation. A sound pressure analysis using
the electromagnetic force obtained with a magnetic field analysis as excitation
force can be used to evaluate the resonance phenomena of transformers caused
by the electromagnetic force and the eigenfrequencies. This note presents
the use of a coupled magnetic field and sound pressure analysis to obtain
the electromagnetic force produced in the core and the sound pressure distribution
caused by the resonance of the eigenfrequency in the transformer.
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 | 20 - Sound Pressure Analysis of an SPM Motor UP!
| Module:DP,DS | 2012-04-10 | As electric motors are becoming more common, motors which create less noise are in high demand. Sound can be divided into categories of electromagnetic noise, mechanical noise, and draft noise, where electromagnetic noise is the most common for medium and small sized motors. Sound can be divided into categories of electromagnetic noise, mechanical noise, and draft noise, where electromagnetic noise is the most common for medium and small sized motors.
The electromagnetic force in a motor vibrates as an electromagnetic excitation force which creates noise. The vibration and noise are generated when the electromagnetic excitation force resonates with the motor's eigenmodes. In order to evaluate this phenomenon more accurately, it is necessary to understand the distribution of electromagnetic force that moves the stator core which is the basis for the radiated sound. The distribution of electromagnetic force or the eigen modes in a model that depends on the geometry of a stator core is required for running an analysis such as for the finite element analysis.
This Application Note shows an example of an evaluation of a reactor's sound pressure, when acquiring electromagnetic force generated by a stator core for a SPM motor and linking the eigen modes of a motor.
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 | 9 - Sound Pressure Analysis of a Loudspeaker UP!
| Module:DS,TR | 2012-04-10 | A loudspeaker produces sound when the voice coil makes the vibrator vibrate. The general requirement of the loudspeaker is to produce uniform sound over a wide range of the frequencies.
Lorentz force is generated in the coil when the magnetic field of a permanent magnet acts on the current flowing through the voice coil, and produces sound by making the vibrator vibrate. In order to evaluate the sound with good accuracy, it is necessary to handle the resonance phenomenon between the Lorentz force and the speaker's eigenmode properly. The eigenmode and Lorentz force distribution change depending on the place where the core and coil are wound, so high accuracy calculations need to be carried out using the finite element method (FEM).
This Application Note presents how the frequency characteristics of sound pressure can be obtained using the constant Lorenz force on the voice coil, regardless of the frequency.
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 | 4 - Sound Pressure Analysis of a Reactor UP!
| Module:DS,TR | 2012-04-10 | Reactors are used in a variety of electric power systems. For instance, they fill the role of making the current pulsation between an inverter and a motor more smooth. On the other hand, the sound that originates from a resonance phenomenon between an electromagnetic force and an eigenfrequency can become a problem.
The reactor in this analysis has a gap in the magnetic circuit to prevent magnetic saturation. Due to the magnetic fields that occur with high frequency currents, electromagnetic force generates near the gap, and this electromagnetic excitation force in turn causes noise. Vibration and sound grow larger when the electromagnetic excitation force and the transformer's eigenmode resonate. In order to evaluate this phenomenon with good accuracy, it is necessary to find the electromagnetic force distribution and eigenmode in the high frequencies that become particular problems by using the finite element method (FEM).
This Application Note shows an example of an evaluation of a reactor's sound pressure when a part of a spacer has been removed.
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