Welcome to Shenzhen KINRI Energy Technology Co.,Ltd. official website!
Language：

Shenzhen KINRI Energy Technology Co.,Ltd.

SHENZHEN KINRI ENERGY

Huizhou (HK) Yingyuan Technology

Support Hotline

137-2371-6834 Timber (WhatsApp)

Shenzhen KINRI Energy Technology Co.,Ltd.
Knowledge
Current Location: Home > Knowledge > Knowledge

Knowledge

0755-29665062

Certificate

Shenzhen KINRI Energy Technology Co.,Ltd.
Knowledge

Why is there sound when the module power supply is working?

Article Source：Kinri Energy | Author：Kinri Energy | Issuing Time：2024.05.23
Sound can be heard by the human ear with frequencies ranging from 20-20kHz. Power audio noise refers to the vibration frequency of electronic and magnetic components generated during operation, which can produce audible signals within the range of human ear hearing. Below is a brief discussion on the main reasons why module power supplies produce sound during operation.


AC DC POWER MODULE

In most flyback power converter applications, transformers are the main source of audio noise. The main reasons are as follows:

Process issues with transformers:

1. Inadequate impregnation and drying of the paint can cause the magnetic core to be unstable and cause mechanical vibration, resulting in noise.

2. The length of the air gap is not suitable, resulting in unstable working conditions of the transformer and producing noise.

3. The wire package was not tightly wound, resulting in noise.

4. The magnetic core combination has an air gap, which causes air vibration and produces noise at high frequencies. If the transformer is fully immersed in vacuum, it generally does not produce sound.

Loop issues with transformers:

1. Improper wiring of the circuit board can cause interference and oscillation, resulting in noise.

2. Improper setting of feedback loop parameters leads to unstable loop, resulting in oscillation and noise.

3. The quality issues of the components in the loop, such as insufficient input filtering capacitor capacity, poor output rectification fast recovery diode quality, poor power MOSFET quality, poor inductance quality, poor high voltage capacitor or diode quality in the RCD recoil absorption circuit, etc., cause oscillations and produce noise.

Transformer core issue:

When the transformer core saturates, the current in the coil increases, causing the transformer to heat up and produce self-excited oscillations. The oscillation of the coil causes vibration in the surrounding air, resulting in noise.

Under no-load or light load conditions, the module power supply may experience oscillation phenomena at certain operating points, manifested as transformer whistling and unstable output. Due to the large instantaneous opening time of the switch during no-load or light load, the output energy is too large, resulting in significant voltage overshoot. It takes a long time to recover to normal voltage. Therefore, the switch needs to stop working for a period of time, so that it operates in an intermittent working mode, which will cause the transformer to vibrate at a lower frequency and produce noise. This problem can generally be solved by presetting a fake load at the output end.

All insulation materials will deform under the pressure of an electric field, and this electrostrictive effect is proportional to the square of the electric field strength. Some insulating media also exhibit piezoelectric effects (i.e. linear displacement proportional to electric field strength), which are the main pathway for capacitor noise generation.

In order to suppress electromagnetic interference and reduce device voltage stress, module power supplies generally use absorption circuits such as RC and RCD, and high-voltage ceramic capacitors are often used as absorption capacitors. High voltage ceramic capacitors are made of nonlinear dielectric materials such as barium titanate, and the electrostrictive effect is more obvious. Under the action of periodic peak voltage, the dielectric continuously deforms and produces sound.

Usually, replacing the high-voltage ceramic capacitor used in the absorption circuit with a polyester film capacitor with a very small electrostrictive effect can eliminate capacitance noise. To determine whether the capacitor is the main source of noise, different insulators can be used to replace the capacitor for testing, but it is important to note whether the replacement can withstand repeated peak currents and voltage stresses.
Back List
Shenzhen KINRI Energy Technology Co.,Ltd.

Scan And Follow Us

  • Phone:+86-137-2371-6834 Timber (WhatsApp)
  • Tel:+86-0755-29665062
  • Email:mkt1@jinruipower.com
  • Add: No. 13A16 Huafeng International Commercial Building, No.4018 Bao’an Avenue, Xixiang, Baoan District, Shenzhen China
Copyright © 2009 Shenzhen KINRI Energy Technology Co.,Ltd. All Rights Reserved.
Clients: Mexican Telecom, ZTE, Mindray, Sony, Microsoft, Toshiba, Ohm Electronics, MT, MG and so on international famous brands