The generation and suppression method of power supply audio noise

The generation and suppression method of power supply audio noise

  • 2020-08-13
  • Views:0

The generation and suppression method of power supply audio noise

(Summary description)

  • Categories:NEWS
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  • 2020-08-13
  • Views:0

One: audio noise generated by the transformer

In most of the flyback converter type applications, audio transformer is the main noise source. Test plate on the first prototype of transformer noise are often surprising. Adopts the structure known as the appropriate skills to basically eliminate noise without additional costs. Pay attention to the finished product performance on assembling prototype transformer of repeatability.

There are several mechanisms that produce transformer noise, each of which produces a mechanical displacement that produces sound. These mechanisms include:
Relative motion - The attraction between the two parts of the core causes it to move, pressing on the medium that separates it.
Impact - If the surfaces of two magnetic cores can contact, their movements in response to the flux excitation will cause them to collide or scratch.
Bending - a crack that exists only in the middle leg of the core of an EE or EI structure that causes each part of the core to follow the direction of the intermediate attraction
Magnetostriction - the size of the core material varies with flux density. The rate of change of ferrite at ordinary power is less than 1ppm.

Skeleton movement - The displacement of the core can be transmitted and amplified through the skeleton.
Coil movement - The current in the coil creates attractive and repulsive forces that move these wires.
Mobile source work together, to form the complex mechanical system, it can within the scope of the human ear hearing one or several frequency point, a strong resonance. Under 10 w off-line flyback converter type commonly used structure generally produce resonance of 10 KHZ to 20 KHZ. When the magnetic flux of motivation fundamental frequency or its harmonics through the mechanical resonance area, mobile sound. The designer should be fully transform load to test audio noise, especially in need of dynamic load.
The amount of noise these mechanisms produce depends on their location. Fortunately, designers can apply simple structural techniques to effectively attenuate the audio noise generated by these mechanisms.


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