Re: Stepper questions

Roy,

Not really.:-) Current thru a winding changes at the rate of Vs / L
amps per second. The current "direction" doesn't come into play at
all except for the sign in front of Vs / L. Current rises and decays
at the same rate either way.

Mariss


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Roy J. Tellason"
<rtellason@...> wrote:

>
> On Wednesday 03 May 2006 11:17 am, Alan Marconett wrote:
> > That's an interesting point! I don't recall reading anything

like that, I

> > could be wrong. Basically the windings do not interact as far as

I know.

> > Actually, one would think that "turning around" a winding, as in

a bipolar

> > drive would take longer. The field would have to collapse before

it could

> > build up in the opposite direction. Therefore wouldn't a

unipolar drive,

> > with its four windings have the advantage?
>
> Ah, but the key here is "rate of change" -- the faster you can get

that

> magnetic field to change, the faster that motor is going to

respond. And in

> a unipolar setup, you're looking at either energizing a winding in

one

> particular direction or not. In a bipolar setup, on the other

hand, you're

> effectively looking at reversing the direction of the applied

voltage, which

> means almost having the effect of twice the applied voltage,

therefore

> tending to increase how fast those magnetic fields are going to

switch

> themselves around, since higher _difference_ in voltage gives you

more

> current flow and a faster rate of change in the magnetic field.
>
> Or at least that's my understanding of it. :-)
>
> --
> Member of the toughest, meanest, deadliest, most unrelenting -- and
> ablest -- form of life in this section of space, a critter that can
> be killed but can't be tamed. --Robert A. Heinlein, "The Puppet

Masters"

> -
> Information is more dangerous than cannon to a society ruled by

lies. --James

> M Dakin
>