Re: Chopper Transient Suppression

You are probably using a "constant off-time" switching topology. The
screeching, grunting, whistling, hissing, etc. comes for free with
that method.:-)

Mariss


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Wayne C. Gramlich"
<Yahoo@G...> wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
> <mariss92705@y...> wrote:
> >
> > .2uS is way to short. The motor winding capacitance results in
> > ringing (multiple cycles, underdamped envelope) for several
> > microseconds. We use a 5uS blanking period (comparator ignore

time)

> > at the start of each switching cycle.
> >
> > Don't depend on the I-sense RC low-pass filter; blank it

digitally.

>
> Mariss:
>
> Thanks. I cranked the blanking up to 4uS and the stepper motor
> vibration is now gone. The stepper motors still produce
> a high pitch screeching noise. Since I've never actually
> seen or heard anybody else's CNC machine to compare against,
> I have no idea whether my stepper noise is typical or excessive.
>
> Thanks for the prompt feedback.
>
> -Wayne
>
> [snip]
>