On Fri, 9 Jan 2009, John Kasunich wrote: > Date: Fri, 09 Jan 2009 14:21:00 -0500 > From: John Kasunich <[email protected]> > Reply-To: "Enhanced Machine Controller (EMC)" > <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Subject: Re: [Emc-users] Simple 3 phase drive > > Peter C. Wallace wrote: >> One of our customers would like to use our small LV 3 phase HBridge (7I39) to >> drive a motor using EMC. I currently dont have a HostMot2 configuration that >> would support this (its normally used with SoftDMC), but the hardware part is >> pretty trivial, just a pinout change. (unless I wanted make a special 3 phase >> PWMGEN with 3 x 10 bit PWM gens at a single write location - thats a driver >> change) >> >> The 7I39 is very simple, its just a 3 phase bridge with current limit so >> the interface requirements are just 3 PWM generators. What I'm wondering is >> if anyone has done simple sine wave PWM 3 phase drive via HAL and >> suitable COMPs alone? > > A while back I wrote HAL components for the clarke and inverse clarke > transforms (three phase to DQ vector and back again). See > > http://www.linuxcnc.org/docview/html//man/man9/clarke2.9.html > http://www.linuxcnc.org/docview/html//man/man9/clarkeinv.9.html
OK > > I intended to write a vector rotate component as well, but never got > around to it. But you could send the sine and cosine outputs of the > siggen component into "clarkeinv" to generate three phase sinewaves. > >> At a 4 KHz or so update rate , waveform quality would be pretty good up to >> normal servo speeds >> > > Is this for a permanent magnet AC servomotor, or just an induction > motor? It seems like for a servomotor you'd need a current loop, which > implies current feedback, which implies A/D converters. Or is it > possible to get decent performance from such a motor with an open-loop > drive? Permanent magnet servo motor. Its possible to get very good performance without a current loop at least for small motors, you may need to add a phase lead feed forward term for very high drive speeds. Of course it is closed loop in the sense that drive voltage is controlled by the normal position PID loop. Not really much different than straight PWM control of a DC brush motor Some (mod) math is required to generate the reference angle from the encoder count of course. I guess I can cobble together a HM2 config at poke away at this. It would be better to combine the 3 phase PWMs so 1 write updates all 3 at once but for testing the normal hardware should be fine > > I'm interested in doing the same thing, but it is one of many projects > and I haven't found that round-tuit yet. > > Regards, > > John Kasunich > > ------------------------------------------------------------------------------ > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
