Gentlemen, My suggestion was to use a stepper of a type built like an alternator. If that concept would be useful. Just throwing out ideas. It may not be feasible but who knows? Definitely not me. :) thanks Stuart
On Tue, Jan 6, 2009 at 11:23 AM, Jon Elson <el...@pico-systems.com> wrote: > Stuart Stevenson wrote: >> Gentlemen, >> I have seen (youtube) the conversion of an automotive alternator to >> a stepper motor. The fields are pulsed and no motion occurs until the >> rotor has dc voltage applied. Would it be possible to use this type of >> stepper to overcome some of the speed and torque limitations of a PM >> stepper? > The problem/advantage of the alternator is it has much lower pole > count. I suspect the pole count is WAY too low for it to be much use as > a step motor. I think most of them are around 4-8 poles. What you can > do with them is use them as brushless motors. Whether the torque ripple > and velocity ripple makes them useful as a servo motor can be debated. > My guess is the ripple is pretty bad, but a tight control loop could > make them work. I know some people have done it. >> Could you reduce the voltage at faster speeds and get better >> performance. Maybe you could size it so more voltage to the rotor >> could give more torque during the cut? >> Just thoughts of someone who knows NOTHING about stepper motors. :) >> > The step driver is basically a current source, and everything it does to > the motor is based on current, not voltage. > You need enough supply voltage to overcome the motors generated voltage > (back EMF) at any particular speed. > > Jon > > ------------------------------------------------------------------------------ > Check out the new SourceForge.net Marketplace. > It is the best place to buy or sell services for > just about anything Open Source. > http://p.sf.net/sfu/Xq1LFB > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Check out the new SourceForge.net Marketplace. It is the best place to buy or sell services for just about anything Open Source. http://p.sf.net/sfu/Xq1LFB _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
