Re: Voltage to steppers

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:

> Jeff:
>
> I have forgotten who it was in the group who just asked this

question, but I

> see that now and then in other kinda-related groups, as well. It

is clear

> most folk do NOT understand that having a DC-SUPPLY voltage several

times

> higher than the motor's "rated coil-voltage" does NOT mean "that

same

> [effective] voltage will be applied to the motor"! Well, yes, it

is, but not

> "at stand-still". NO MORE than that rated coil-voltage should be

applied,

> "effectively", so that the rated CURRENT does not exceed! This

concept of

> the increase of coil-REACTANCE when spinning is something most

folk "in here"

> just don't grasp, and this is understandable! (I'm not even sure I

do!!!)

>
> We need some guru like YOU to explain about how a CHOPPER-drive

keeps the

> "effective" current at the proper limit, and why the HIGH voltage

the drive

> CHOPS does not cause excessive current (due to DUTY CYCLE of the

chopping)

> and that!
>
> And how the "old" L/R "six-wire" unipolar system was WASTEFUL and
> inefficient, and how a power-supply for a CHOPPER system can be

much smaller

> than the old L/R system, etc., etc! Do YOU volunteer???
>
> Jan Rowland
>
>

Hi,

It occurred to me that if the controller program kept track of the
steps per second, it could also predict the current needed from the
power supply.

Also, one could write the controller program to limit the current
needed from the power supply by limiting the steps per second. When
the steps per second approached the limit, the program could stretch
out the clock period such that the issuing of step pulses to the
stepper motors is slowed uniformly.

Is this in any controller program?

Newbie Stan