PDA

View Full Version : Inductors for Phase leads



SplinterOz
21 May 2013, 0340
Ok I can't search for nuts! Just a little while ago (in my life at the moment that could be 6 months) I was on the forums reading about inductors for the phase leads on a BLDC motor with low inductance. Tritium actually had a pdf on how to make some.

Then someone posted a link to a NEW thing. These looked like ferrite cores but you just put the phase wire through them. If you wanted more inductance you put more on.

Now I cannot find the post.

HELP please.

(just one of those weeks)

jonescg
21 May 2013, 0357
How many turns at what gauge? You can't possibly get more than two or three with that cable?

SplinterOz
21 May 2013, 0408
See that was the thing... the solution had no turns... just the phase wires straight through. Think of an inductor built in reverse... the ferrite core on the outer... made in little rings and the lead with the current straight through the middle. Only gave small inductance but really high amps (as the leads carry the power)

Not describing it well but look at this...
4451

And think of the outer coil being closed rings and the inner core being the phase lead. The changes in current on the phase lead induce current in the ring and the BEMF then retards/slows etc the current like a normal inductor.

nebbian
21 May 2013, 0503
Google for clamp on ferrite bead. You can find them wrapped around computer data cables -- they are usually easy to remove.

SplinterOz
21 May 2013, 0518
nebbian... yep like that only designed to replace what are called load reactors, and the ones shown on the thread I can't find look like rings and you just stack more of them along the cable until you don't saturate at the current you want.