Hi, I'm new here and i'm looking for peple that have some hnowledge into EMI.

I am reaching out to you because I work in an small company specializing in machining, and we lack the in-house expertise to resolve this type of issue. Activating the frequency converter creates electromagnetic interference, which disrupts the electrical valve of the pneumatic cylinder and the Arduino.

The pneumatic part of the bench is controlled by an Arduino microcontroller. The Arduino program works correctly when the frequency converter (single-phase to three-phase) is connected but in the "off" position. However, as soon as the converter is turned "on," the Arduino and the valve become unstable, and the control section functions erratically.

We have tried several solutions to resolve this issue, and here are our findings:

• Moving the Arduino outside of the metal cage improves its operation; however, the valve still switches randomly.
• If I am in contact with the metal cage and touch a component of the Arduino, it becomes unstable again.
• Connecting the converter to a different power outlet in the company makes no difference.
• If I connect the converter to a battery (see battery link), I no longer experience interference issues.
• Adding an EMI filter upstream of the converter produces no noticeable improvement (see EMI filter link).
• Moving the frequency converter out of the room does not change anything.

I would like to know if you have encountered similar issues, and if so, how you resolved them. Could it be that the battery has a high-frequency filter that mitigates these EMI issues?

The next steps I am considering to solve this are:

• Installing an EMI filter on the output of the frequency converter.
• Using shielded cables for the connections entering and exiting the converter.

I am at a standstill and am advancing step by step. Any advice you could provide would be greatly appreciated.

Thank you very much for your time.

 

Where do the 0V connections go from the two power supplies, and are they connected to earth?

 

Where do the 0V connections go from the two power supplies, and are they connected to earth?

I'm not entirely sure if I understood the question correctly, but yes, all 0V connections from both power supplies are linked to the ground."

 

I'm not entirely sure if I understood the question correctly, but yes, all 0V connections from both power supplies are linked to the ground."

Where? Are they both linked to earth at each power supply, or at the power input to the arduino? How is the 24V supply 0V connected to the 5V supply 0V?

 

Where? Are they both linked to earth at each power supply, or at the power input to the arduino? How is the 24V supply 0V connected to the 5V supply 0V?

The arduino is powered by my computer while testing

 

Looking at the picture of the motor connection box it looks like you are using normal 3 core mains cable between the VFD and the motor. (Using the earth conductor for one phase.) So you don't have an earth conductor between the VFD and the motor. It is recommended that you use 4 core (3 phases and earth.) screened cable between the VFD and the motor with the screen only connected to earth at ONE END.

Les.

 

+1 on using screened cable. A star ground system would be advisable, so that no heavy currents can affect the Arduino or other sensitive parts.

 

Screened cable from VFD to motor. 4 cores cable needed-L1,L2,L3 and PE .

I do not understand your circuit- what mean "Transistors" in oval ?

 

It seems that the frequency converter is generating far more radiated signal then is allowed. There are limits to such radiation that are actual LAW. so it seems that the frequency changer/3 phase generator that you have was probably selected by the cheapest price. Purchasing folks often do that.