You will, once Luke's weighed it.teslanv said:I'd love to see Death Bike's Motor in this database...
You will, once Luke's weighed it.teslanv said:I'd love to see Death Bike's Motor in this database...
liveforphysics said:speedmd said:You will not be able to do that with normal plastic wire insulation. 2/0 is good for 2300 amps, 3/0-2700 amps for ten seconds before they evaporate in a poof of smoke going by the chart. You will need some high temp wire insulation or go bus style with some heat sinking.
That fusing current chart seems to be on the extremely conservative side of things. My own test experience (which I can repeat on video if you like) shows cables not fusing nearly so rapidly at those current levels. I think it's worth looking into the test process for collecting the fusing currents, my hunch is maybe that the test it conducted while the cable is already at maximum temperatures or something.
.Maximum (theoretical) power output occurs at half of no-load speed
Punx0r said:This is shifting the topic back a bit, but I'd just like to reconcile something for the sake of my own understanding.
In the thread titled "PM Motor theory - formulae etc." (http://endless-sphere.com/forums/viewtopic.php?f=30&t=16376) Miles states:
.Maximum (theoretical) power output occurs at half of no-load speed
Bearing in mind the post is from 2010, is this just out of date, or applicable to a brushed motor on a non-current limited supply?
Otherwise it implies (to my mind) that a fast-wind motor cannot produce the same power as a slower wind at a given speed?
Punx0r said:To make more power we either spin faster and use gear reduction, or keep speed the same and increase torque by growing radius and increasing tooth count? The limitation in both cases being core losses from increased commutation frequency?
liveforphysics said:....Alternatively, you could mount the magnets on a ring with more radius (something like ~3.16 x larger radius), and now they move faster past the teeth and develop increased torque as a result of applying the torque on a longer lever-arm.
In otherwords, having a big diameter hub motor accomplishes the torque increasing effects without having additional system losses, complexity and failure modes of gearing vs having a tiny motor spinning quickly. The reason we aren't all rocking massive diameter hubmotors is only because someone hasn't made a lightweight, high efficiency, and economical massive diameter hubmotor yet. From a performance perspective, it has the potential to be the lightest and most efficient and highest continuous power. Something like tiny 2-3mm teeth wound with all half-turns (just a tiny rectangular copper bar being woven through them to wind) and a ring of tiny magnets, but on a radius close to rim size. Existing controller tech likely wouldn't power it very effectively due to the ultra high commutation frequency, but that doesn't mean it's not possible to do, just hasn't been done yet.
Kingfish said:Analysis of typical Radial Flux Iron-Core Motor having variable winds
Concerns & Declarations:
- Claimant posits motors of the same manufacture/series having the same load and speed and wheel diameter will use the same power regardless of the number of winds.
- Effects of Controllers, Batteries, Cabling leading up to the Motor connectors are to be ignored; let us not introduce distraction. Presume these items are of top-flight quality and can deliver ideal power always. The claim is about the Motor, and nothing else.
...
Further analyses will be forwarded as free-time allows over this holiday.
Happy thanksgiving in advance, KF
johnrobholmes said:I'm with you on single or half turn coils (wouldn't it only be a half turn if the phase starts and stops on opposite sides of stator?) being an ultimate design, although the labor saved in winding seems to be offset by the trouble to get all the coils connected in my limited experience.
liveforphysics said:Kingfish said:
- Presume –
- Same Motor, except for winds <- the only physical difference.
- Winds use the same AWG; you said same same same same… therefore everything is the same!
No, the copper fill is what stays the same, nobody is talking about just unwinding copper off a stator and then comparing it's performance... Talk about pointless Trolling to spread misunderstandings...
I don't think we need FEM to resolve this oneteslanv said:However if one wants to truly understand torque as it relates to number of winds, this is the most basic of concepts.
teslanv said:liveforphysics said:Kingfish said:
- Presume –
- Same Motor, except for winds <- the only physical difference.
- Winds use the same AWG; you said same same same same… therefore everything is the same!
No, the copper fill is what stays the same, nobody is talking about just unwinding copper off a stator and then comparing it's performance... Talk about pointless Trolling to spread misunderstandings...
For the record, this is exactly the point where KF and John/Luke diverge.
KF is pushing the concept that in his theoretical model, the winds are NOT the same copper fill, but rather a common total cross-sectional area, where higher number of turns will result in proportionally more copper fill than a lower number of turns.
Kingfish's statement is 100% valid, if you accept his parameters.
This argument is not about math or engineering, but about the acceptance of the Copper Fill parameter. Luke and John outright refuse to accept this different copper fill parameter because it is not common practice. However if one wants to truly understand torque as it relates to number of winds, this is the most basic of concepts.
Arlo1 said:A motor winding person would not do it any other way the goal with every slot is always to fit as much copper as possible once you find the # of total strands that can fit through a slot you will always use that number its just a matter of how many are parallel and how many are in series (series is # of turns . No matter the combo the number of prices of copper stays the same with the same gauge of copper.