Microstepping thru the Tulips

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 Mattison
http://www.ohmikron.com/