Re: Xylotex or Gecko step driver for my Mill/Drill?

Hi,
When you use bipolar series on a 6-wire motor (end to end, center
tap not used), you are using twice the number of wire turns per phase
when compared to half-winding (or unipolar). A unipolar motor is
rated for the amount of current running through a single coil -
center tap to one end, and it's associated number of wire turns. The
torque produced from the motor is a factor of the current and the
number of wire turns it is running through. If you double the wire
turns you need to halve the current. Although the wire can handle
the higher current, the motor should not be run over its' rated
current (for half-winding/unipolar) or half that current for series
winding.

With a given unipolar motor, bipolar series lets you use a stepper
motor driver that needs to handle only half the amount of current
that half-winding would require (and this can end up being a less
expensive drive). This comes at the expense of higher
inductance, thus slower coil charging (at a given voltage) (which
leads to lower torque at higher speeds).


Jeff
http://www.xylotex.com

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Nick Ibbitson"
<pulseweld@d...> wrote:

> in answer to you question
>
> Thanks for the clear explanation there. Now, I have another

question: Is

> it feasible to use a motor with six wires (that an ohmmeter shows

me as

> being
> wired for unipolar operation) as a bipolar motor by simply ignoring

the

> center taps? I'm wondering about the phasing of the two half coils

there...

>
> Yes. But you have to assume half the amps per phase (apparantly) so

a 2amp

> unipolar can run at 1amp bipolar.
> Im no expert but thats what it says in my Xylotec pdf.
>
> Nick
>
>
>
>