Greetings!

I am rather new to stepping motors.

I have only made driver for small motors and used very slow stepping with
constant voltage.

Now I want to drive a larger bipolar stepping motor.
Requirement is about 2-4A per winding, peak voltage upto 45V.

Anybody know a nice driver for that?

This is a one-off that i want to play with and learn a lot from.

Also, i'm thinking about heat generated in the motor, which is hard to get
rid of in this compact machine.

First, as I only need little holding torque, I plan to reduce current to
half, giving 1/4 heat, when stopped.

Space is very limited, so i plan using 150% or so of rated current, at
acceleration and retardation, so i can get the most out of this motor.

The drivers are of course regualtong the *current* thru the windings.
That is normally accomplished by the driver using switch-mode operation,
with the windings as the inductor.

This make the winding heat up extra due to whirlcurrents (is that the
word?), and also heat the magnetic material due to magnetization.

Better use linear drive, but that will give *very* high heat in the driver.

Maybe very high switching frequency, and LC filter before winding?

Or linear driver, which communicates with the switch-mode power supply to
adapt the driver supplu voltage to the currently needed voltage?

 or??

Ideas, anybody?
Or URL's, hints, chips, etc.

And to keep this on-topic,  ;)
any nice ideas/routines for ramping etc?

One thing iĞm concerned about is that the stopping point might change while
moving (updated stop position), so it has to recalculate the stop ramp any
time that change, for being able to stop correctly at worst-case change, or
even lock to and follow that changing position....  (the stop position
change rate can be given guaranteed limit).  Well, that is my headache.
One nice thing is that the mass is low, and the friction high, so stopping
is much easier tah accelerating, and i have no perticular demands on
acceleration rate.

Regards
/Morgan

/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  mrt@iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /