Microstepping

Hi,

Since I haven't seen a 'technical' reply yet, I'll add my two-pennorth for
what its worth.

If I understand it right the principle is as follows:-
In a 'normal' stepper driver, a fixed voltage is applied to each coil in
turn but in alternating directions. This makes the adjoining polepieces in
the motor'flip' from one magnetic state to the other - i.e. either North or
South poles of equal strength. This makes the motor move in definite jerks
or 'full steps'.
Now, in a microstepping drive, the same principle applies except that the
voltages applied to the poles are not equal. So, rather than always applying
full voltage to the windings, the voltage is reduced so that one winding
might get, say, 3/4 the voltage while the other gets 1/4. Doing this means
that, rather than the armature flipping completely from one polepiece to the
next, the relative difference in magnetic strength fo the poles will make
the armature turn only 1/4 step and 'hover' between the poles. The next step
would be produced by altering the voltages to 1/2 - 1/2 and then 1/4 - 3/4
before the next full voltage change produces the full step.

I may not have the technicalities exactly right but I'm sure others will
correct me. I think this is usually still done as discrete steps but, if a
true sine wave is applied, the motor should run as a synchronous motor.
I may be wrong???

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk