Re: Running Unipolar steppers with a Bi-polar driver?

Hello Peter,
When you run stepper motors in bipolar mode you will be driving
twice the amount of copper (compared to unipolar). This turns into
TWO times the resistance, and FOUR times the inductance the drive has
to overcome, thus the time to fully energize the coils will DOUBLE.
As you start getting faster and faster step rates, your drive doesn't
have time to fully charge/discharge the current in the coils to the
proper level. Thus at HIGHER step rates bipolar can end up having
less torque than unipolar (given equivalent voltages for both
drives).
The good news is that the holding torque, or torque at slower step
rates will be about 1.414 times MORE than a unipolar drive. This is
where most of the power is really needed; when cutting metal at the
slower, non-rapid feed rates.
If you can find datasheets for your motor, they might show torque
curves for both unipolar and bipolar. You can go from there when
deciding on whether to choose a bipolar or unipolar drive.

Jeff
www.xylotex.com
The XS-3525/8S-3 is a bipolar 3 Axis 2.5Amp 35Volt Stepper Driver
board

--- In CAD_CAM_EDM_DRO@y..., "Peter Homann" <peter.homann@a...> wrote:
> Hi,
>
> I am thinking of running my 200 oz/in Unipolar steppers from a
bipolar
> controller. Can anybody provide advice on what sort of power/speed
reduction
> I can expect?
>
> Thanks,
>
> Peter Homann
> mailto:Peter.Homann@a...
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