Can a Motor Have 7 Poles?

Research the term "magnetic monopole". Then think about the the integer "7".

No, it has to be an even number. You can't have a north pole without a south or a south pole without a north. There's no such thing as half a magnet!

sevenpolemotor

Here's a 3-pole design:

Funny, I count eight poles.

The arrangement shown looks like it would produce four poles....though not evenly spaced.

Imagining field lines, it seems very likely that a meaningful portion of those lines will make the complete loop between the poles that exhibit the same outward polarity..... in the illustration, the electromagnets at 9:30 and 1:30 (o'clock) will have some field lines that connect blue and red via a path centered around 11:30...making it effectively a pole aligned red out at 11:30.

If you google 7 pole motor . . . you'll find what you're looking for.

You can even buy them.

This is from WEG in Poland, still only six.

sure you can! it wont spin but you go ahead and build it, you sound like a smart guy

Yes there are odd numbered pole motors just as there are odd pole numbered alternators.

For years Ford vehicles had alternators with 12 rotor poles but 11 stator poles.

The principle also works in reverse for special application motors as well.

Yup...

http://www.ebay.com/itm/German-import-31MM-DC30V-3300rpm-Micro-motor-Seven-pole-miniature-DC-motor-/151490132395

Certainly there can be motors with 7 poles, though these are not common.

The most straight forward would be a linear motor.

There are also likely examples of a different sort in the vicinity of Warsaw.

I thought that cogging in motors where it might be a problem was usually handled by an odd number of rotor "poles" and/or rotor slot angled to the direction of rotation. i.e. not 90° as usual.....

Also, the OP never mentioned why he needed 7 poles in the first place!!!

Maybe 14 poles would also do it (assuming that 14 poles are available on the open market, I don't have a clue either way!)

Thanks for your reply.

Just to be a smart ass, any motor with 8 or more poles by definition ALSO means it has 7 poles...

So does that make a smart ass (or even a middling donkey) twice the biped a typical human is?

Yes. Romford produced a 7-pole motor as a drop-in replacement for the Tri-ang X04 motor. They aren't made any more, as the pulse-width-modulating controllers made anything with more than 5 poles wasteful but you can get them occasionally on eBay. I'd expect to pay £15-20 each, plus postage.

7 is not a lucky number. That why we only have , 2 pole and 4 pole motor only.

Poles will be in pairs only. You cannot built 7 poles motor because a motor should have rotating magnetic field which is possible only with the help of pair of poles only. Hence it is not possible to build 7 poles motor.