Welcome to Our Community

Some features disabled for guests. Register Today.

VFD EMI causes Blackbox controller serial disconnect

Discussion in 'OpenBuilds Forum Help' started by Tom Lindley, Mar 18, 2020.

  1. Tom Lindley

    Builder

    Joined:
    Mar 6, 2020
    Messages:
    8
    Likes Received:
    0
    I am working on bringing up a blackbox controller on a Cnc4Newbie machine. I am currently testing the integration of the VFD spindle/relay and that seems to be working fine, but with a catch. When I fire up the spindle, i lose communication with the controller. I can adjust the +10 output voltage to get the proper RPM but cannot communication with the controller. I have to power down the controller and restart.

    I read a thread about interference with the VFD signals and removed the VFD cable from the tracks. I now have the VFD running overhead with the water lines. This is a 220v spindle and the regular Chinese inverter. It does trigger the IoT relay when it powers up the spindle.

    I also have a USB filter on the computer but that didn't seem to make a difference. I plan to test manually starting the spindle today, but wanted to see if there were any glaring issues I have missed.

    Thanks!
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    15,046
    Likes Received:
    4,313
    VFDs put out a tonne of EMI interference
    You'll need to add some mitigation against that EMI:
    - space VFD inverter away from other electronics, ideally in a grounded metal enclosure
    - use shielded wire between inverter and spindle and space away from any other wiring
    - make sure spindle body is earthed
    - add ferrite cores on all other wiring, usb cable with ferrites will help too
    - avoid USB hubs, go as short and direct as possible

    One of the big disadvantages of a VFD over a router sadly
     
  3. Tom Lindley

    Builder

    Joined:
    Mar 6, 2020
    Messages:
    8
    Likes Received:
    0
    So do you think the VFD is the root cause of this? Thanks.
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    15,046
    Likes Received:
    4,313
    Definately. High inductance motor, high rpm, 400hz 3 phase AC, and the chinese cost cutting all come together for a perfect storm (more expensive inverters have built in noise suppression)
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice