If you pinch to similar poles of a magnet together as the gap closes the lines of force compress and begin to move outwards at 90 degrees to the face of the magnet, thus producing a very focused pole. So if two electromagnet coils were positioned in a similar fashion in a pulse motor then the cores could be positioned further away from the rotor. Hopefully this would produce less core drag.
I believe ( after checking ) that it could be described as a scalar N
As you know with your own rotor / core experiments , the drag that can exist between the rotor and the core ( due in part to the core retaining some degree of magnetism ). So one option would be to increase the distance between the rotor / coil and to compensate increase the power to the coil ( wasteful + increases retained magnetism ). So if two coils were used , with say the core faces cut at 45 degrees with respect length of the core and then so arranged as to have both faces of each coil parallel to each other ( thus forming a "Y" shape ). This would produce a very strong magnetic pole when energised but would have a very small drag footprint when switched off.
This would then allow magnetic field switching . Example.... take two small identical magnets allow one magnet to support a weight ( that it can only just manage to support ) on its pole face edge. Bring a similar pole face towards this magnet and the strength increases but if you bring an opposite pole face into position the holding magnet will drop the weight.
Yes , i see what you mean but in this case you are not only reducing the magnetic footprint of the rotor you are also reducing the footprint of the magnet hopefully giving more kick and a lot less drag.
Hi ron-o What you have described sounds like you want to set your coil's up as buck coil's ah-la L.A.G setup-it works exactly the same-see description in circuits and diagram's section. You are spot on with your asumption that the magnetic field will increase at a 90 deg angle to the coil's thus the reason the L.A.G coils are at 90 deg to the rotor magnets. So now you will totaly understand how the L.A.G works and the rotor speeds up when a load is applied without drawing extra current to run it-because the core between the run and generator coils increases in magnetic strength as a load is applied to the generator coil because the generator coil starts to produce an apposing magnetic field to the run coil. So now you have the two north fields metting at the core creating that magnetic field at 90 deg to the rotor magnets. Like my avatar use to say-swim at 90 degrease to the current and gain speed in two directions . lol