Hey guys ,
today i mounted odrive and original odrive motor with mechanical gearbox mainly made from aluminium and steel. I noticed that the USB connection is breaking on each command. I measured the voltage between Odrive - and the housing of the motor (which is also electricly connected to each metal part in the gearbox) and i wasn’t expecting to see that voltage goes up to 20V. Im not really good with electricity but i started to look why is it happening and how can i solve the problem. I found that there is a phenomenon called shaft voltage ( occurs in electric motors and generators due to leakage, induction, or capacitive coupling with the windings of the motor). Is this the case here ?
Can I connect the motor housing to the - terminal of the odrive in order to ground the motor. Is there a risk to damage any component if I do this.
Thank you
Use the ferrite rings. They will reduce capacitively-coupled common-mode noise 
And yes, grounding to the negative side of the ODrive is sensible - but definitely use the ferrites as well.
UPDATE:
The ferrite rings didnt help us a lot with this problem. We had to tape the motor shaft with iso-tape in order to isolate it from the other part of the metal gearbox. We tested only the motor(original from odrive) and odrive controller setup to see if that problem still appear and yes it is still there. If you touch the metal shaft of the motor with another metal piece it disturbs the usb connection.
I’ve tried to earth the chassis and that didn’t bring a lot of success too. Yesterday i changed the USB cable and since then I don’t lose the connection so often. So far this had the most success with my problems
Hi, for the USB problem I would suggest a USB isolator, and for the shaft voltage I would suggest a ferrite ring on the phases. After mounting the ferrite ring you will still see voltage on the motor body, but this is typically not an issue since the ferrites should remove any fast edges that may cause EMI. The ODrive brand motors are anodized so it’s not easy to ground their body. If having some small current through the gearbox is a problem then I would suggest the brushes that @Wetmelon suggested.
Hi,
thank you for you response. I haven’t tried the ferrite rings properly since I only have one ferrite ring with a small inner diameter, so i can’t do any turns around it and only put the 3 wires together through it. I have USB Isolator, but it didn’t helped with this particular effect. I managed to decouple motor from other metal parts with 3d printed shaft coupling. After that my USB connection works without any problem.