It's absolutely a cost issue, and the servo drives are way to exotic for this project. I only need a small motor that just drives or brakes according to the rate that the computer sent. I had an idea of letting a thyristor shopping up the frequency, but it would be much easier to run a DC motor and then decrease the power in a classic DC-motor-rpm controller way (cut the DC into a square wave). If the value given is under 0, switch to a heat sink and let the motor act as a generator. If the value is above 0, switch to power and turn the square code on. I still think it's not more than a 12 V ~30 W motor we speak about - maybe not even that. What do you think?
2008/12/20 Dale Ertley <[email protected]> > Can't we run an AC servo in a + or - torque mode, based on a + or - control > voltage applied to the servo drive? Clockwise rotation (torque force) for + > and CCW for a - control voltage. The servo tries to maintain a commanded > torque output. Forcing the motor shaft to rotate. I would think DC servo > drives will do the same. > Dale > > --- On Sat, 12/20/08, Javid Butler <[email protected]> wrote: > > From: Javid Butler <[email protected]> > Subject: [Emc-users] Off topic-Electrical design help > To: [email protected] > Date: Saturday, December 20, 2008, 1:08 PM > > Is there a reason such as cost or space that an off-the-shelf drive for the > motor cannot be used? > > Some of the new drives have the capabilities that you are looking for built > in. > I was just hearing the other day about a Siemens drive that is even line > power > regenerative-when the motor is being used for braking the energy is not > dissipated in a resistor bank, but is put back into the power line. So the > braking energy is actually powering the lights in the building (for > example-you > could thing of it as running the air conditioning too). > > The energy efficiency is not quite the point here, just that a drive may be > available for that motor that already has the drive/braking capability you > need. > > Unless you are wanting to work it out for the fun of doing it, which is > something I completely understand! > > Javid > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
