EMI Issue on a special made machine

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.

Hi,

you should post some photos of your application including wiring.
100kBytes per photo should be suffcient.

Klaus

Motor cables, inverter and motor chassis grounding are the critical points. Shielded motor cables are a good idea, but they should involve low inductance shield connection to inverter and motor chasssis, otherwise they may be effectless.

Arduino board has zero EMI hardening.