Shashijain said:
is there any effect of no. of poles on the maximum step frequency???
Frankly I don't know.
But I've made up some thaughts.
If stepper motor is driven only by a set of basic H-bridges, wich mean voltage over coils can be just on or off, I guess that greater number of poles could lead to shorter spikes/frequency when rpm remains the same as for a regular motor.
But I have to admit that I doesn't have any experience with steppers with 5 poles or more.
I beleive a multipole stepper can be set up in different ways. t.ex a configuration will allow it to run without any H-bridges. Regular transistors in open colector configuration will do the job. In such a configuration, any pulse should have shorter duration than on a similar regular stepper when rpm is the same.
However, the logic driver circuit (or program) still may allow multiple coils being active in same time.
So bottom line is: I think there is no "yes" or "no" answer on that question, because what matters more than number of poles is how the driver circuit is set up. I guess a DAC on each input to the stepper (very sophisticated driver) may be the way that allow the stepper to run fastest of all methods. In theory it will alow the stepper to move smoothly from one step to another.
However, a 7-pole stepper compared to a 4-pole stepper is possibly designed for better precision, that is smaller steps.