> On Sunday 30 June 2019 11:31:28 Nicklas Karlsson wrote: > > > On Sun, 30 Jun 2019 10:39:27 -0400 > > > > Gene Heskett <ghesk...@shentel.net> wrote: > > > On Sunday 30 June 2019 06:18:24 Roland Jollivet wrote: > > > > A while back there was some discussion on using an induction motor > > > > as a servo motor. I can't find the thread.. > > > > > > > > Yesterday, at the scrapyard I hauled two of these exact motors off > > > > a roller press; > > > > http://www.lithronix.com/komori/komorimatic-water-fountain-roller- > > > >actu s-power-motor-rebuilt-ni20-200fg-x4kt > > > > > > > > I was quite disappointed to find out there was no permanent > > > > magnets in them, and there were no matching drives. > > > > So they are induction, but perhaps made differently to your > > > > general induction motor. > > > > It's a beast of a motor for 200W... At least they come with a > > > > 1000 P/R encoder > > > > > > Since the link doesn't say how many wires go into the motor, if its > > > 2 or 3 phase etc, its hard to make good guesses. > > > > > > If its a 3 wire motor, a small 250 volt input vfd would be a good > > > driver, and I would couple the encoder up to feed back to the vfd, > > > such that you'd have a position servo. You would need to program the > > > vfd to not shut down at the lower frequencies, and to not deliver > > > more than the 1.3 amps per winding even when the vfd thinks its > > > detecting a locked rotor. The encoder, for a position servo would > > > need to be something that could be converted to ABX because you'd > > > need to record the home position as x counts from the index. And > > > I'd gate the z signal thru the home switch. Home by driving to the > > > home sw closure, then track the counts to the z signal running in > > > the same direction and call that home. > > > ... > > > > Vector control is needed for fast dynamic response, it's a little bit > > extra tricky for induction motor. > > > > > > Nicklas Karlsson > > > How so, Nicklas? I am reverseing a normal 3 phase 1 hp century induction > motor thats probably 50 yo, fast enough to make the spindle belts yelp > in my 11x54 Sheldon. With a 1.5 hp rated clone vfd. Its sequenced > somewhat in my .hal file, basically by turning the vfd down to about 10 > hz, then stopping it which puts dc on the windings, and when the encoder > says it is slow enough, gating the reversal on thru and ramping it back > up to speed. Makes the belts yelp but the vfd doesn't complain.
Well if you take your time it is possible to run, it's a simple algorithm and work well. Vector control is only needed then there is a need for fast and accurate response otherwise I also use simpler algorithm. Nicklas Karlsson _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
