ACDC front-stage EMI filter style issue

zhaoyanhao

ACDC front-stage EMI filter style issue [Copy link]

 

Hi, teachers!

ACDC power supply needs to add EMI filtering circuit under poor working conditions or higher EMC requirements. Conventionally, it is Y capacitor, X capacitor, common mode inductor, differential mode inductor and the like. However, I found that the order of components in each filter is mostly different, and the positions are before and after according to the current direction. Take the example described in the manuals of different models of modules from the same manufacturer. Their Y capacitors and X capacitors are in different positions. One is before the common mode inductor and the other is after the common mode inductor. Some Y capacitors and X capacitors are before the common mode inductor. Some differential mode inductors are after the common mode inductor and some are before the common mode inductor. Is there any deep consideration for such setting? Is it fixed according to the ACDC topology or calculated and experimentally matched? Is there any big difference in effect due to different positions? Everyone is welcome to express their opinions.

maychang

[The order of components in each filter is mostly different, and the positions are front and back according to the current direction]

It should be said that [the positions are in front and behind according to the direction of energy transmission].

maychang

Is there any big difference in effect between different positions?

There doesn't seem to be any big difference.

zhaoyanhao

maychang posted on 2023-6-30 09:49 [The order of the components of each filter is mostly different, and the positions are front and back according to the current direction] It should be said that [the positions are front and back according to the energy transfer direction...

Haha, teacher, you are right. My statement was not well thought out.

lkh747566933

Thanks to the OP, it is very good sharing. I don’t know how to do it, so I will learn it in my spare time.

led2015

The order of components in the EMI filter is determined based on specific design requirements and optimization processes. Different position orders may result in slight differences.

lkh747566933

The order of components in the EMI filter is determined based on specific design requirements and optimization processes. Different position orders may result in slight differences.

dabiaoke

The different positions of the inductor X capacitor will affect the impedance matching, while the different positions of the Y capacitor will have an impact on the interference signal filtering of the input and output.

zhaoyanhao

dabiaoke posted on 2023-7-5 16:30 The different positions of the inductor X capacitor will affect the impedance matching, while the different positions of the Y capacitor will have an impact on the interference signal filtering of the input and output.

Thank you for your reply. Is there any detailed technical description for me to learn?