Originally posted by alexelectric
View Post
I've been telling you that efforts you spend on "magnetic neutralization" are a waste of time. You (Turion and I assume Alex also) claim that the force of attraction between the magnet on the rotor and the core on the stator constitutes "magnetic drag" and is responsible for load on the prime mover. This attraction force occurs at alignment of the magnet and core, a position called TDC (Top Dead Center) and also either side of TDC rotation. This attraction force when not at TDC manifest in torque on the shaft, center of rotation. When at TDC, the attraction force is axially directed, perpendicular to the plane of the rotor, and parallel to the centerline of rotation (shaft), therefore torque from the attraction at TDC is zero. Zero torque is zero load on the prime mover.
So the attraction force between the magnet and core does load the prime mover when not at TDC, however,, the torque causing this loading is opposite in direction for clockwise (CW) vs counterclockwise (CCW) displacement from TDC. Since the force is symmetrical about TDC, the torque imposed on the rotor is net zero per rotation from this attraction. Hence my contention that magnet to core attraction is irrelevant to power.
This attraction of magnet to core is cogging. I never claimed it went away or disappeared at speed, just that it is irrelevant to power. Turion has acknowledged that yes, cogging torque approaching TDC does offset departure from TDC and rotor momentum can smooth it to where it can be unnoticed, but insists that the attractive force at TDC still loads the prime mover. He claims this force between the magnet and core at TDC resists rotation so an opposing force will eliminate this opposition and power loss associated with it. He doesn't believe me or Newton that there is already an opposing force in place.
Newton tells us that for every force there is an equal and opposite force. So at TDC, there is a force of attraction on the core and on the magnet in the direction perpendicular to the plane of the rotor and parallel to the centerline of rotation, shaft. The magnet experiences a force towards the core. Where is the equal and opposite force? It is provided by the adhesive holding the magnet in place on the rotor. And then the rotor to the shaft. Then the shaft to the bearing. Then the bearing to the stator. Then to the core. And finally back to the magnet. An equal and opposite force. Newton is happy, equilibrium. The opposition force is already there in the structure, otherwise the magnet and core would move together. The fact that there exists a gap between the magnet and core proves there is a counteracting force.
I've based the above argument on the case of a single magnet on the rotor and a single core in the stator. It's a valid argument and holds. However it occurred to me having read this recent exchange with Alex, that there is another equal and opposite force on the particular design used in Turion's big black generator. Perhaps he can appreciate this.
Turion uses magnets on both sides of the rotor disc. And has two sets of stator coils/cores, one on each side of the rotor, call it front and back sides. And the magnets are equal in number on the front and back of the rotor and aligned radially around on the same diameter. The stator cores are also aligned, such that when the front magnet is TDC, the back magnet is TDC. So the attractive force between the front side magnet and core at TDC is equally offset by the magnet and core on the back side. If the front core pulls the rotor East, the back side core pulls West. Equal and opposite.
You already have your opposition neutralization magnets. No additional hardware required.
But it's all moot because these forces are axially directed such as not to cause torque. And torque is what loads the prime mover.
bi
Leave a comment: