Printed Pole Motor

I remember reading a book about motors, and one of the more interesting ones was
referred to as a "Printed Pole Motor" IIRC.
This motor had multiple salient poles on the rotor, and they could be
re-magnetized as they passed one location of the stator.
This allowed the pole count of the rotor to be dynamically changed by
re-printing some of the salient poles to create larger or smaller groups of
North or South poles in succession around the rotor.
I think they were intended for very large motors for ball mills or some large
mining operations, of low speed, and thus many poles around the rotors.
Also, it was suggested that since the poles could be re-written as the motor
ran, there could be theoretically non-integer numbers of poles around the rotor,
as they could be dynamically printed to match the required speed.
Google cannot find any information on this...
Did I forget the actual name of this class of motor?
Reply to
Cross-Slide
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was referred to as a "Printed Pole Motor" IIRC.
re-magnetized as they passed one location of the stator.
re-printing some of the salient poles to create larger or smaller groups of North or South poles in succession around the rotor.
mining operations, of low speed, and thus many poles around the rotors.
ran, there could be theoretically non-integer numbers of poles around the rotor, as they could be dynamically printed to match the required speed.
About 30 years ago, I saw, at a trade show, a UPS based on a flywheel. They claimed that they printed the poles dynamically so you got 60Hz out independent of flywheel speed.
Reply to
mike
Sounds wacky; I've never heard of it.
Dunno how it'd work with rare earth magnets -- you'd need a honkin powerful magnetic field at the "printer", and it'd need to be fast -- and those two don't go together well.
I suspect that as a PM motor technology it probably made sense if the best magnet material you had was AlNiCo (which is really easy to demagnetize and remagnetize), but with rare earths (which aren't) you get a huge efficiency advantage from the magnet's strength, and a huge increase in difficulty of remagnetizing the thing, so the net result may be that it's not worth it.
For a Really Honkin' Big motor it may make sense to have a bunch of poles on the rotor, made with rare earth magnets, that can be mechanically flipped, and a bunch of servoes to mechanically flip them under control from some smart algorithm -- but that's not "printing".
Reply to
Tim Wescott
Tim Wescott fired this volley in news:cbWdnQiGtZ0q8cLNnZ2dnUVZ snipped-for-privacy@web-ster.com:
I remember that. It came out as an article in Popular Science or Popular Mechanics somewhere between the 60s and 90s, though I cannot put my mental finger on when.
I don't think the concept ever made it to production, but the prototypes seemed to work.
LLoyd
Reply to
Lloyd E. Sponenburgh
I vaguely remember something about using them in a generator. Googling "magnequench" didn't help, though it brought up a sad account of leading Dems betraying the US by selling the technology to China.
Reply to
Jim Wilkins
interesting
I believe you may be thinking of a "Written Pole Motor"
They offer some advantages for motors in the 10 to 100 HP range when single phase power must be used. I recall them as being relatively expensive.
WayneJ
Reply to
WayneJ
I believe they are now used in high-end machining centers as a way to get very wide speed ranges at full HP without using gearing or belt drives. I think they are also called switched reluctance motors. They do not use any permanent magnets, but rewrite the poles on an iron rotor.
Jon
Reply to
Jon Elson
Thanks for the replies! Sorry it was not a political rant. I was simply curious about something I read years ago...
IIRC switched reluctance motors use soft iron in the rotor poles, and rely on magnetic attraction to the poles. Most motors have permanent or electromagnets to react against. And the switched reluctance is yet again something different than a written pole motor.
Always something interesting to learn about...
Reply to
Cross-Slide
Apparently " printed" pole motors are now called "written" pole motors. See this link:
formatting link
for an explanation. Eric
Reply to
etpm
Only called that by this maker. Note the (R) (registered trademark symbol -- the letter 'R' in a circle) everywhere it is used, and this note about ahla way down (where the (R) symbol is showing as "\256" on my screen, showing that it is a non-printing character on this system. But it may show up properly on yours.
====================================================================== Written-Pole® is a registered trademark of Precise Power Corporation. ======================================================================
And the printed motors which I have seen (and which I have a few examples of) are DC motors, while these are AC for the standard power line -- single phase or three phase.
Enjoy, DoN.
Reply to
DoN. Nichols
I've hot a (big) handfull of printed circuit DC motors - some of them complete with the servo tach mechanisms from old industrial robots looking for an application. HEAVY little critters witk cast steet? frames.
Reply to
clare
The motors I'm talking about are not printed circuit motors. The poles are "printed" or "written" on the rotor as the motor spins. This way the motor can have any number of poles on the rotor at any time. Each time the rotor spins the magnetic poles can be changed by a winding in the stator. Look at the link provided. And also note that as DoN pointed out the term "written" is a registered trademark for this particular type of AC motor. Eric
Reply to
etpm
I am aware of the AC written pole motors. Basically computerized re-wiring of the stator for different speeds .
Reply to
clare
If you go to the link provided or to the Precise Power web site you will see that the AC written pole motors being discussed here are not "Basically re-wiring of the stator". The rotor has an outside layer of ferrite that is re-magnetized by a single winding in the stator. So it is not the stator that is changing but instead is the rotor. And the motor is analogous to a permanent magnet synchronous motor that has a provision for changing the magnets in the rotor. But instead of pulling the motor apart and and changing the number of magnets in the rotor the and reassembling the motor the written pole motor just magnetizes the rotor with the desired number of poles. Even 1/2 poles. Go to the link and read about these motors. Eric
Reply to
etpm

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