"Hi, .........but wouldn't even simplistic thinking give you a time
factor in there so that the influence between the magnet and the electro
parts as the motor rotates mean that adding magnets might merely smooth
out power pulses, as each pull/push 'association' has less time to do
the work?"
factor in there so that the influence between the magnet and the electro
parts as the motor rotates mean that adding magnets might merely smooth
out power pulses, as each pull/push 'association' has less time to do
the work?"
Yes, that is often done. Smoothing the "cogging" by adding more impulses per revolution is pretty common.....in the same way that adding more cylinders smooths a compression motor. But take another look at the cutaway view of that particular motor we were discussing. In that one, it looks as though the magnets are oriented to hopefully increase the flux in each circuit rather than to increase the number of circuits. My point was that since magnets are themselves not very good conductors of magnetic flux, that means that in a series magnetic flux circuit the resulting flux isn't additive. So using a single strong magnet is not the same as using two magnets that are half as strong.
It's sort of off the subject, but since you brought up the smoothing. It's an interesting sidebar that another way to smooth the cogging bumps as an electric motor rotates is to skew the magnet/coil geometry away from perpendicularity so that each time a coil and magnet pass one another the resulting "bump" is not as severe. Of course that also means that the overall torque is lower, but depending on the application there are other ways to make that up.
"Again, thinking in basic terms, an electric motor only uses
electro-magnetism because it is switchable, and conventionally one of
the two main parts need the magnetic field to be switched on and off.
Thinking outside of the box, possibly also outside the scope of this
group, maybe a motor could use permanent magnets on both components, and
use the electricity to kind of mechanically change the magnetic field
distance of influence maybe by individual pole rotation or it's
shielding somehow?"
That's an interesting thought. BTW, nice piece of out of the box thinking...fun to think about. Offhand I don't think I've encountered a motor that uses permanent magnets on both rotor and stator and then uses electrical current to modulate the flux path. But it wouldn't surprise me to find that someone has made a rotating motor on the principle that you mention or even that they are common in some industry.
I've done something similar a couple of times using a small motor to rotate a bar magnet which then alternately pushed and pulled a large ferrous structure. It wouldn't have been much good for driving a propeller, but could be just the thing for a flipper drive.
To make your interpretation work would require finding a way to use material or geometry so that a small current could make a large change in the permeability of the path between the rotor and stator's permanent magnets. Then it would be merely a matter of timing the change in permeability to get it to rotate. Seems worth a try.....
Doing that type of computer R&D is EXACTLY where computer modeling we mentioned is very powerful. You can draw a cross section through an imaginary motor and play with magnetising various parts, changing materials and gaps, and running current through coils. My favorite for doing that is the simple but powerful - and free - program FEMM . (with thanks to the author, David Meeker).
Keep imagining,
Roger L.
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