Re: H bridge progress

Jon,
Good ideas! I have a Class D Audio bass amp that
has a 'reconstuction'filter on the output with a
similar role as the filter you describe, before
the speaker.

Does your high-side sensing give a linear feedback, or an opto
or translated feedback to the drive circuitry? I like your idea of
incorperating it into the drive as high-side current sense.

-Lee

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> Lee Studley wrote:
>
> > Thanks Jon,
> >
> > I wondered what those inductors were on the picture of
> > your servo amp. I thought they might be a chopping/pulse sensing
> > arrangement for the current limiting circuit. IGBTs are fine
> > for this application and yes I'm driving them hard and controlled.
>
> I just use a low-inductance resistor for current sensing. The fault
> sensing is on the high side, so it can detect a fault to ground,
which
> would be missed by the typical low-side current sensing.
> I also have another low-inductance resistor in series with one of
> the motor leads, and read out the voltage across it with an
instrumentation
> amplifier for current feedback in the torque loop.
>
> Jon