Re: Stepper motors and increased Amps

Hi Roman,

Yes, these sound like the same one's that I have. Mine are 2 inches
high, double stack. I will run them at 1A or less based on your
information. I am driving these with Dan Mauch's 5AMP modular bipolar
chopper driver boards. I have the current set at 1A at this time, but
is is easy to reduce it to .707A. I bought Dan's boards so that I
would not have to replace the controller as I increase the size and
power of my machines.

Thanks for the information.

John

--- In CAD_CAM_EDM_DRO@egroups.com, "Roman Black" <fastvid@e...>
wrote:

> --- In CAD_CAM_EDM_DRO@egroups.com, "John Guenther" <jguenther@l...>
> wrote:
> > Tim,
> >
> > The motors have 6 wires, red, red/white, black, green, green/white
> and
> > white. Black and white are the common between 4 coils according

to

> the
> > document supplied with the motors. Black and White are not used
> currently.
> >
> > I am basically curious as to whether increased current increases

the

> torque
> > provided by the motor. These are rated at 59.7 oz/in holding

torque

> and 34.7
> > oz/in pull torque.
>
> Hi John, I think I can help. I am using surplus
> Sanyo Denki 5.1v 1.0A size 23 (2 stack motors
> which are 2" long) in my home mini mill, and I
> have just done a lab test on them last week.
>
> Running bipolar full-copper (ignoring centre tap)
> at 1A was 10.2v. This is ok, and is the same
> dissipated heat power as "two windings on"
> unipolar drive at 5.1v 1.0A.
>
> If you plan to run bipolar two-phase-on mode
> you have to de-rate current to 0.707A per
> phase to give the same heat dissipation.
>
> I measured torque for one phase on bipolar
> 1A 10.2v at 5.3kg/cm (about 75 oz/in).
> If your motors are 2" long this will be
> very close to your figure too.
>
> Now you won't gain much from increasing the
> current as 23 frame motor current ratings
> place the motor very close to core saturation.
>
> For example, here are some torque and heat
> dissipation figures I measured:
>
> 1A 10.2v 10.2w 5.3kg/cm (one phase on)
> 0.71A 7.6v 10.2w 5.95kg/cm (two phase on)
> 0.57A 5.9v 6.7w 5.3kg/cm (two phase on)
> 1.2A 14.0v 16.7w 5.5kg/cm (one phase on)
>
> The last one, the over-current test is what
> you are asking, increasing current from 1.0A
> to 1.2A gave ONLY a 4% increase in torque,
> but dissipated 64% more heat and wasted power.
> This shows the official 1A rating of the motor
> is very close to magnetic saturation. Most
> 23 frame motors are rated this way.
>
> If you are interested I put up the chart of
> the exact phase currents needed to reach all
> 8 microstep values at exact angular position
> and the same torque. See:
> www.ezy.net.au/~fastvid/stepper8.gif
>
> (the dots are theoretical standard current
> values the crosses actual current values).
> I think this motor is almost identical to
> yours, I have 2" length 5.1v 1.0A motors
> in my junk box from a few manufacturers.