RE: [CAD_CAM_EDM_DRO] Stepper motor 101 was Re: Are steppers considered low frequency motors?

> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Mariss Freimanis
>
> I've seen those traces before and I think they look awful. "Square"
> step motors are optimized to produce torque that is the vector sum of
> both phase currents.
>
> The goal from a drive standpoint is to have this torque vector
> magnitude be a constant. This means torque is independent of motor
> position (on a full-step location or in between) and the motor turns
> smoothly.
>
> The only function that does that is sine and cosine (sqrt(sin^2 +
> cos^2) = 1) which is why microstepping performance is optimal if the
> winding currents are accurate sinusoids.
>
> I was going to post to the files section a 'scope current-probe pic
> gif file but it seems I can't do that here.
>
> Mariss
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Alan Marconett" <KM6VV@...>
> wrote:
> >
> > Hi,
> >
> > So what about Linistepper?
> >
> > http://techref.massmind.org/techref/io/stepper/linistep/index.htm
> >
> > Appears to be an attempt to do a linear ramp (triangle?) to drive a
> stepper?
> >
> > Alright, it's got a PIC on it (I like that), but I see two BIG
> resistors, for a unipolar driver.
> >
> > If we really want a sine wave, why don't we just use a linear amp
> and drive
> > it with a sine wave? Class A (B? even C?...) Wastes too much
> power I'll bet.
> >
> > Alan KM6VV
> >