Re: Tawagawa Seiki steppers

Hi Alan,

Now this is useful. I guess it's been a few years since I read Jones on
stepping motors! One coil is always breaking? And that acts like a
damper? Sounds like some nice motors for CNC, if you can find/build a
driver. Thanks for the comments! Now to find a set of motors...

Alan KM6VV


alan@... wrote:

>
> Hi,
> Just joined this list, and reading through recent messages. Having
> gotten 3 Berger-Lahr 5 phase motors along with a 5mW HeNe laser for
> free from an LKB densitometer that was thrown out, I did some
> research and have a little knowledge on these.. Berger's site is
> terrible for these, when I looked a while back there was zero drive
> info anyway, although the site's changed some now. Jones on stepper
> motors has 5 phase drive info (bottom of the page):
> http://www.cs.uiowa.edu/~jones/step/types.html
>
> First off 5 wire and 10 wire are basically the same thing, the 5
> wire just have the coil ends tied together already. 10 wire motors
> are simply seperated and you tie the coil ends together on the
> outside normally. But just like the 8 wire steppers give you choices
> in operation over a 6 wire, the 10 wire does have an extra way to run
> it.
> Draw a pentagram of coils with the ends tied together. Now go
> around it, label each point + and - to energize the coils. Look how
> that one coil always has either two + or two -, and is in braking
> mode not powered. Look at Jones' drive table and notice there are
> two adjacent +'s or -'s in each state. 5 wire (or 10 wire wired this
> way) are run like this, and it's part of why they're so smooth and
> low vibration, one coil is always braking and damping the motion.
> But only 4 coils are on. The real advantage to this way is you only
> need 5 half bridges, one at each corner that drives one side of two
> coils.
> With a 10 wire, you can power each coil seperately, so you can
> power all 5 coils. But you don't get the built in braking, so more
> vibration (although still quite good compared to 2 phase motors), and
> you need 10 half bridges to run them this way, one for each coil
> end. Needless to say between the loss in damping, only 25% power
> gain, and doubled semiconductor cost,most are run in the penta
> arrangement. They can also be run in a star tied in the center,
> which has some advantages over penta with still only 5 drive points.
> It's similar to the wye in a 3 phase motor. But almost everything
> I've heard of ran them as a pentagon with one phase in brake..
> I have pictures of mine if anyone wants to see for comparison,
> they're small (NEMA 23 single stack), yet all 10 wires are still
> brought out. They're .76 deg/step or .36 deg/half step, so easily
> get a direct 1000 points per rev. 5 phase motors can also run smooth
> and fast, they're better than 2/4 phase for some applications, just
> with a little more drive and programming required. Mine were
> positioning X-ray films and moving a mirror to scan the X-ray with
> the laser to digitize the film, and determine the bone density
> accurately. Largely replaced with hires scanners and computer
> software now, but still very cool to watch it move things around.
>
> --- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> > Hi Brian, Carey,
> >
> > Thanks for the comments. As I've mentioned, I'd just curious to
> see how
> > they drive 'em. Got lost on Berger's site. Saw pix on physical
> dim's,
> > etc.
> >
> > Alan KM6VV
> >
> >
> > "Carey L. Culpepper" wrote:
> > >
> > > Five phase motors come in two flavors. Five wire or ten wire. My
> newest motors
> > > and all of my drivers are five wire. I haven't figured out how to
> hook up the
> > > ten wire motors yet. All of my five phase motors are Vexta (under
> license of
> > > Berger/Lahr).
> > > Carey
>