Transformer abnormal sound

zhuyu630

Transformer abnormal sound [Copy link]

 

I have made a 300W half-bridge switching power supply with TL494, and the output voltage is 40V. Now I have encountered the problem of transformer noise. I have tried all the methods and I don't know where to start. Please give me some advice.

Description of the problem: The transformer will not make any noise when it is unloaded, lightly loaded, or continuously overloaded. It only makes noise when overloaded (it feels like the core is contracting).

Solution: Currently, transformer intrusion, vacuuming, glue dispensing, and thickening of wire diameters are all unsolvable.

tagetage

You've basically said all the solutions. All I can think of is to try changing the core to a bigger one.

led2015

It is nothing more than the transformer process problem, transformer loop problem, transformer core problem and switching power supply load problem.

hp880229

It is normal for the transformer to make noise.

qwqwqw2088

A kind of noise in the transformer is caused by magnetic saturation, that is, saturation will occur under a certain current, causing abnormal operation of components and possible noise.

zhuyu630

led2015 Published on 2023-3-31 23:26 It is nothing more than the transformer process problem, transformer loop problem, transformer core problem and switching power supply load problem

The transformer process has been processed as needed. The loop problem should be eliminated. It is caused by the load problem. Because the load is constantly switching on and off, the transformer is sometimes unloaded and sometimes fully loaded.

zhuyu630

hp880229 posted on 2023-4-1 06:08 It is normal for the transformer to make noise. There is no way

Leaders don’t think so

zhuyu630

qwqwqw2088 posted on 2023-4-1 08:14 The transformer has a kind of sound caused by magnetic saturation, that is, saturation will occur under a certain current, causing the components to work abnormally and there may be a sound. ...

How can I verify whether it is saturated? Please advise

zhuyu630

These are the transformer parameters, input voltage 220VAC 20%, output inductor is wound with PQ3230 75uH 2.0*60P

zhuyu630

qwqwqw2088 posted on 2023-4-1 08:14 The transformer has a kind of sound caused by magnetic saturation, that is, saturation will occur under a certain current, causing the components to work abnormally and there may be a sound. ...

If it is magnetic saturation sound, it will sound under full load. At present, it does not sound under full load (320W), and it works very stably under full load for a long time. The ripple temperature rise parameters are all OK. It is because the load at the back end is constantly switching on and off, and the sound comes out.

tagetage

zhuyu630 posted on 2023-4-1 08:53 If it is magnetic saturation sound, it will sound under full load. At present, it does not sound under full load (320W), and it works very stably under full load for a long time. The ripple temperature rise...

It will ring under full load, but it will also ring during transient high power output.

Is your load an inductive or capacitive load, not a pure resistive load? Try changing it to a pure resistive load.

I told you on the second floor, try changing the magnetic core to a bigger one.

zhuyu630

tagetage posted on 2023-4-1 09:17 It will ring under full load, but it will ring under transient high power output. Is your load an inductive or capacitive load, not a pure resistive load? You can change to a pure...

It does not make a sound under continuous full load (320W), but it makes a sound instantly when loaded. It is a pure resistive load with a resistance value of 7.5R. It is mainly because it is constantly switching on and off under load (many times in 1 second). The magnetic core cannot be enlarged at present.

tagetage

zhuyu630 posted on 2023-4-1 09:32 It does not make any sound under continuous full load (320W), but it makes a sound instantly when loaded. It is a pure resistance load with a resistance value of 7.5R. It is mainly because it is constantly switched on and off under load (switching many times in 1 second)...

Full load and instantaneous load are different. If the full load does not make a sound, it does not mean that the instantaneous load will not make a sound. You can also try to increase the output filter capacitor and increase the switching frequency. How many times do you switch in 1 second? ? ?

qwqwqw2088

zhuyu630 posted on 2023-4-1 09:32 It does not make any sound under continuous full load (320W), but it makes a sound instantly when loaded. It is a pure resistance load with a resistance value of 7.5R. It is mainly because it is constantly switched on and off under load (switching many times in 1 second)...

The instantaneous sound may not be caused by magnetic saturation.

But in this case, it is most likely a transformer problem, or as tagetage netizens said, try changing the core.

tagetage

The instantaneous noise under load is actually more difficult to deal with than the noise under full load. Another method is to replace the magnetic core with other materials of the same volume.

qwqwqw2088

Transformer processing technology and materials are all possible

Or change the transformer manufacturer with the same parameters

zhuyu630

tagetage posted on 2023-4-1 10:12 Full load and instantaneous load are different. If you don't make a sound when fully loaded, it doesn't mean you won't make a sound when you are instantaneously loaded. You can also try to increase the output filter capacitor and improve the opening...

I have increased the output filter, but it is still the same, about four switches per second on average. I will try to change the core of other materials to see if it works.

tagetage

zhuyu630 posted on 2023-4-1 10:41 I have increased the output filter, but it is still the same. It switches on and off four times per second on average. I will try to change the core of other materials to see if it works.

What kind of magnetic core do you have? Ring-shaped? Buy a few big brands to test. Did you buy a domestic brand?

zhuyu630

tagetage posted on 2023-4-1 10:56 What kind of magnetic core do you have? Ring? ? ? Buy a few big brands to test, is the one you bought a domestic brand? ?

The transformer was directly made by the manufacturer. I don’t know much about the brand.

tagetage

As for the core material, choose a big brand, for example, Tiantong Co., Ltd.