R1T Wheel v Ford Inboard motors

[jimcgov3]

Welcome back, @ajdelange!!

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[Interferon]

No. The wheel bolts directly to the rotor.


That is how they work. Lots of poles. This does not result in more torque. The rate of rotation of the magnetic field is inversely proportional to the number of poles so the field for a 24 pole motor takes 12 times longer to go through 360 ° than a 2 pole motor. To get 12 times more torque requires 12 times the number of turns or 12 times the current or some combination thereof such as 3 times the number of turns and 4 times the current. And or stronger magnets.

Thinking about this a bit more there are more places (poles) where the torque is applied but they have to be smaller to fit,

With only a couple of poles, each pole has to drag the rotor through a large lateral magnetic gap on each cycle. With lots of poles, each pole piece only has to pull through a small distance. So it is like a lever, giving it more torque.
Another way of looking at it is that speed * torque = Amps * Volts, both ways of measuring power. So if a multi-pole motor has less speed for the same power, it necessarily must have more torque for the same power.

 

[ajdelange]

Yes, as the motor is turning slower it does have to produce more torque to develop the same power. Where does the torque come from though? At each air gap the torque developed is the cross product of the stator and rotor field vectors. And there are twice as many air gaps as poles. So if there are 24 poles the motor would produce 6 times the torque of a 4 pole motor if the PM field strength, number of turns and current were all the same. So that's really where the question lies to my way of thinking. Are these obviously physically smaller poles as "powerful" as the ones in a 2 or 4 pole design. I think the answer must be "yes" or nearly so as these hub motors obviously have to torque/power curves comparable to those of the 4 pole motors in a more conventional (Tesla, Rivian) design.

The lever analogy doesn't really work here.

 

[CommodoreAmiga]

The lever analogy doesn't really work here.

Seems to be a good analogy, to me. Have you ever watched the GM produced video on “spinning levers”? It was used to describe transmissions, but I think it can also be applied here.

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