Arduino Forum

Using Arduino => General Electronics => Topic started by: cjdelphi on Apr 18, 2013, 04:18 pm

Title: A brushless Motor?
Post by: cjdelphi on Apr 18, 2013, 04:18 pm
Inside one..

(http://static.ddmcdn.com/gif/brushless-motor-1.jpg)

What if the magnets were removed and replaced with electro magnets
instead...

Q1 Feasible?
Q2 providing it has no drastic flaws in this idea.... would that be less or more efficient?
Title: Re: A brushless Motor?
Post by: afremont on Apr 18, 2013, 04:47 pm
I don't see any permanent magnets in that photo, I only see the electromagnets (stator).
Title: Re: A brushless Motor?
Post by: fungus on Apr 18, 2013, 05:01 pm

Q1 Feasible?
Q2 providing it has no drastic flaws in this idea.... would that be less or more efficient?


a) No advantage over simply making those coils bigger.

b) How will you connect the electromagnets to a rotating thing? Brushes...?

Title: Re: A brushless Motor?
Post by: MarkT on Apr 18, 2013, 11:34 pm
The permanent magnets(*) spin round with the fan, replacing them with electromagnets would require slip-rings....

(*) often in these small fan motors the magnets are actually a single strip of rubberised ferrite material inside the rotor bell
and magnetised with a repeating pattern of N-S-N-S poles.

The whole point of a brushless motor is to avoid the problems with having to conduct current to a spinning armature
via slip-ring or commutator - one less thing to wear out.
Title: Re: A brushless Motor?
Post by: Docedison on Apr 18, 2013, 11:50 pm
Probably make a good motor though.. If you used the rubberized Ferrite magnets the torque might be somewhat low...

Doc
Title: Re: A brushless Motor?
Post by: MarkT on Apr 19, 2013, 04:02 pm
The pic on this page shows the arrangement of magnetisation in a typical small brushless motor:
http://www.youritronics.com/implementing-a-brushless-dc-motor-controller/ (http://www.youritronics.com/implementing-a-brushless-dc-motor-controller/)
Title: Re: A brushless Motor?
Post by: samarkh on Apr 19, 2013, 05:49 pm
If you did this you would be making a brushed motor.
Yours Simon M.