Electric noise from a fan & multiple current sources

EMHmark7

Hi,

1) If I wish to put a cooling fan for cooling motor drivers on the same power supply as the one sourcing one of the 2 stepper motor pairs.
(total of 2 power supplies + the digital side from USB power)
Should I put some electrical stabilization for protecting the digital circuitry?

My motor power source is 12V/4A and the digital is sourced by USB through Parallax Flip board.

2) I do not remember why, but I managed a while ago to have TWO DC power supplies 12V/4A, each driving 2 stepper motors, besides the Parallax Flip board for digital sides.

Does anybody see any possible problem between the two power supplies working in parallel? (Of course all on a common Ground).

Thanks
Marc

Mike Green

It's generally a very bad idea to connect two power supplies in parallel unless they're designed to work in parallel. They're usually not identical and one will begin to supply more current than the other then overheat and shutdown or become damaged then the other will have to supply the whole load and it will shutdown or become damaged ... you get the picture.

Regarding the cooling fan and digital circuitry. It depends on the type of cooling fan motor, the amount of power involved, the power supply for the digital circuitry, the supply for the whole thing (fan + digital). USB has current limits too.

The Flip has its own voltage regulator and filter capacitors. Some cooling fans have their own digital driver and don't generate much noise. It all depends on the details.

EMHmark7

Thanks for reply. But as I said, each power supply would supply 2 stepper motors through a stepper motor driver (total of 4 motors). Only grounds would be common. You still feel a possible problem?

I am kind of afraid to use an 8AMP PS.

Thanks
Marc

lardom

EMHmark7 wrote: »

Thanks for reply. But as I said, each power supply would supply 2 stepper motors through a stepper motor driver (total of 4 motors). Only grounds would be common. You still feel a possible problem?

I am kind of afraid to use an 8AMP PS.

Thanks
Marc

You also said: "Does anybody see any possible problem between the two power supplies working in PARALLEL? (Of course all on a common Ground)."

Mike Green

One power supply for each 2 steppers should be ok, particularly if there’s one dual stepper driver or two single stepper drivers per supply. What about the fan(s) and Flip? Details matter.

Mike Green

Remember that shielding may be needed and you shouldn’t run high current wires next to digital signal or digital supply wires ... The high current pulses can induce significant noise in the signal or power supply wires even with a foot or so common routing.