RE: [CAD_CAM_EDM_DRO] Re: Question on Power Supply - regulated notes - motor information

Hi George,

PICs are MicroChip's line of self-contained computers on a chip. Pulse
width modulation is a means of turning the power to a motor on and off,
"chopping" it, so that speed is controlled.

Stepper motor drivers use chopped drives to quickly get the current up in a
winding, then limit it.

We use these small computers in industrial controllers to pump liquids. The
PWM (and a servo loop) allows us to control the speed of the motor, and thus
against a timed period; the amount of liquid dispensed.

The PWM, speed feedback (either EMF or Hall effect tach), and some
computations constitute a servo loop.

A similar application would be for a spindle speed controller. Its
implementation (for a small lathe/mill) would not be much different. A PIC
could receive a speed command (say S2000) from a CNC controller, and with
PWM control the speed of the spindle motor.

Mmm, might have to do that! Actually, it's already been done for the
Sherline mill/lathe.

Alan KM6VV

> -----Original Message-----
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: Question on Power Supply - regulated
> notes - motor information
>
> Alan,
>
> Just learning - PWM "pulse width modulation"? No clue what PIC is
> please enlighten us newbies.
>
> Thanks
>
> George
>
> ----- Original Message -----
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Subject: RE: [CAD_CAM_EDM_DRO] Re: Question on Power Supply - regulated
> notes - motor information
>
>
> > Hi Dave,
> >
> > That's true, but we also have the condition of running out of product
> (what
> > we're pumping), I'd thought of monitoring the current, but that changes
> the
> > load on the pump as well! We drive the motors PWM with a PIC.
> >
> > Alan KM6VV
>