Re: Microstepping thru the Tulips

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Phil Mattison"
<mattison20@...> wrote:

>
> I've seen a lot of comments about microstepping on this board
> as if it is the best thing since sliced bread. I wonder how
> many people have thought about the relationships between step
> rate, PWM frequency and motor inductance. Since microstepping
> supposedly uses the PWM chopper to regulate current into
> something like a sine wave to improve motor performance, it
> stands to reason that if the step rate gets anywhere near the
> PWM frequency that theory goes out the window. Also, the motor
> coil inductance puts an upper bound on the step rate at which
> the PWM does anything at all. Exactly what those limits are
> depends on the combination of motor inductance, power
> supply voltage, chopper switching speeds and probably several
> other factors with less impact. So to say that more microstepping
> is better than less is like saying that blue is better than
> orange.

Phil:

It sounds like you are wondering why we like microstepper
drives. For me, the value of microstepping is that it
helps to avoid the dreaded stepper motor resonance problem.
In general, the stepper motor resonance problem will show
up before PWM frequency issues rear their heads.

-Wayne