RE: [CAD_CAM_EDM_DRO] Re: Clarification for microstepping requirement

Hi Paul,

The MicroStepper I'm using just adjusts the current in each phase to a
fraction of full motor current. Each Microstep increases the current by
sin(x) where x is between 0 and 90. Search for the data sheet on the
LMD18245 for an explanation on the micro-stepping.

The 20KHz to 25kHz are for limiting the current. Once the current reaches
the rated value for the motor the hardware shuts off the current and then
waits until the current has dropped below the threshold. The data sheet
also describes how that works.

The Microchip datasheet referred to in the E-Leadscrew list also discusses
how one form of Microstepping holds one phase at full current and just
microsteps the other one in order to create a stronger holding torque.
After I finish the E-Leadscrew design I was going to change the table in my
stepper driver to see how that would work.

John Dammeyer

>
> The other thing with microstepping, and I'm happy to be
> corrected here, is
> that microstepping is done by varying the duty cycle of two coils. The
> frequency of the signial is often fixed and typically around
> 20-25KHz. This
> means that a 5KHz step signal results in a MAXIMUM of 4
> microsteps per step.
> At 10KHz, or 1KHz with a step multiplier set to 10x, you can
> only half step.
>