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Behind the electromagnetic noise: Why do your electronic devices make strange humming sounds?
In modern life, electronic devices are everywhere. From computers to televisions, without exception, all produce various sounds during use. In particular, a phenomenon called electromagnetically induced sound (EIS) is responsible for causing our devices to hum inadvertently when they operate.
"Electromagnetic noise is a common phenomenon in electronic and electromagnetic devices. The root cause of this phenomenon is the vibration of materials driven by electromagnetic forces."
Causes of electromagnetic noise
Electromagnetically induced sound mainly comes from the vibration of materials under the generation of electromagnetic force. Common examples of these sounds include the hum of a power supply, the hum of a transformer, and the squeal of some spinning motors.
These sounds can be grouped into several categories, including "party noise" and "electromagnetic vibrations." This type of noise is usually caused by tiny vibrations inside the conductor when the electromagnetic field acts on the conductor. If the frequency of these vibrations is between 20 Hz and 20 kHz and the intensity of the sound is high enough, we can hear their presence.
Electromagnetic noise in electromagnetic equipment
In motors, electromagnetic torque and torque ripple (or "flutter torque") are important factors that cause sound. Torque ripple causes torsional vibrations in the rotor and stator, which can sometimes produce audible sounds. This is because when electromagnetic forces coincide with the natural frequencies of a structure, these sounds are amplified.
Resources and Applications
For unavoidable noise, we can use modern computational simulation technology to test and improve it. By combining mathematics and physics, we can better understand the sources of these noises and ways to reduce them.
"The frequency of sound is closely related to the strength of electromagnetic force, so choosing the right structure and material is the key to reducing sound."
Common Types of Electromagnetic Noise
- Transformer: The noise generated when the load changes comes from Lorentz force and magnetoelasticity.
- Inductors: Stored magnetic energy is converted into sound. When the air gap structure changes, it intensifies the vibration inside the inductor.
- Capacitors: In unstable current waveforms, the "singing capacitor" phenomenon may occur.
Methods for reducing electromagnetic noise
To reduce these noises, engineers have explored a variety of countermeasures, including improving design, choosing appropriate materials, and avoiding resonance.
"Using the correct slot and pole combination design and conducting in-depth analysis of electromagnetic vibration can effectively reduce noise."
Future Outlook
As technology advances, we are finding many solutions to more effectively control electromagnetic noise. From the composition of sound-absorbing materials to changes in motor design, future efforts will be made towards quieter driving.
While this noise may be a minor issue for some people, it can be bothersome in certain circumstances. Have you ever been annoyed by the noise of electronic devices in your life?
