RE: [CAD_CAM_EDM_DRO] Re: Tawagawa Seiki steppers

There must be some variation on this theme between manufacturers (or just
plain preference) because my interpretation of Sanyo-Denki's excitation
sequence shows three adjacent coils energized with one of the five
connections floating.

Here is the link:
http://www.sanyo-denki.com/Servo/60mm.pdf

I agree with everything that has been said and I see how this can work, but
I wonder if there is a significant advantage to having 3 or 4 windings
energized.

Any thoughts welcomed.

-----Original Message-----
From: alan@... [mailto:alan@...]
Sent: Wednesday, August 01, 2001 2:03 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Tawagawa Seiki steppers


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



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