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Question about power capacity of electrical motors.

I read that the Tesla electric motor is able to achieve its remarkable power to weight ratio of 8.5 kW/kg, about 10 times better than a typical gasoline engine, because it tightly winds its copper wires in its coils therefore being able to carry more current in the same space. If so, then we should be able to produce more power if we have a material that can carry more current.

Carbon nanotubes are such a material. In tests they can carry orders of magnitude more current than ordinary conductors such as copper, aluminum, or gold. The problem is they've only be able to be produced for short lengths, a few centimeters at most.

But an interesting research on nanotube-copper composites showed they can carry a 100 times more current than standard copper. So for the same size electric motor we could produce 100 times more power than currently:

Posted: Aug 06, 2013 Novel CNT-copper nanocomposite delivers a 100-fold increase in current density

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For the Tesla that would not be as major a deal because of the small size of the motor at only about 32 kilos for the Tesla S, a vehicle that weighs thousands of kilos.

But that would be major for large scale motors used in other scenarios. These can weigh thousands of kilos, and could then be reduced to only tens of kilos. It would also be especially important for proposed electric aircraft that many groups are working towards.

So is it really true we can increase electric motor power levels simply by using wire of higher current capacity?

Bob Clark

---------------------------------------------------------------------------------------------------------------------------------- Finally, nanotechnology can now fulfill its potential to revolutionize

21st-century technology, from the space elevator, to private, orbital launchers, to 'flying cars'. This crowdfunding campaign is to prove it:

Nanotech: from air to space.

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Reply to
Robert Clark
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We have such a material and it is called silver.

Current density and power are two different things.

The actual issue is temperature rise because of winding resistance.

The problem with electric airplanes is the lack of a power source that is comparable to gasoline or jet fuel not the weight of electric motors.

No, you need to reduce resistive losses and/or get rid of heat.

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Jim Pennino
Reply to
jimp

On Sat, 15 Jul 2017 13:43:55 -0400, Robert Clark

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Got a super-battery to go with your super-motor, though?

Reply to
Cursitor Doom

Solar cells work so long as you stay above the cloud and keep to the lit hemisphere!

piglet

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Reply to
Piglet

Only for powered sailplanes otherwise the area available to collect energy is too small to meet power requirements.

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Jim Pennino
Reply to
jimp

Teslas accelerate in short manic bursts. The motor would fry if it ran steady-state at full power.

And the power/weight ratio drops a lot if you include the batteries.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

..

Very true - the Tesla Model S could not complete the Nurburgring course at one time because the motor overheated. The motor is liquid cooled - even the rotor has oil passing through the center.

I don't know about the Tesla but the motors in other EVs are designed with a peak to average load factor of 3 or 4 to 1.

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Not only that but increasing the copper usage efficiency doesn't reduce the weight of the magnetic material which is at least 50% of the weight.

kevin

Reply to
kevin93

That would make the chop shops happy.

Props are rather old-school, too.

And.

Reply to
krw

The albatross is a proof-of-concept that covers fish-powered flight. There's enough energy storage for overnights, too. So one needs SOMETHING for energy, but it doesn't have to replace hydrocarbons, it only has to replace fish.

Reply to
whit3rd

You can build one with superconductors, but you have to be careful of three things:

  1. Type 2 superconductors have AC losses. Preferably, this would be done with type 1, at LHe temperatures.
  2. You can't use magnetic materials very well. Well, you could -- but you'd only be gaining a paltry ~tesla before saturation, when you have several tesla available with the superconductor. They'd also be lossy, putting out heat that you don't need.
  3. The cryocooler is going to set you back more, in space and power, than doing it with copper in the first place, not to mention the expense (and making slip rings, and low resistance connections, and..).

Although one neat thing is, you can avoid slip rings by using a superconducting loop for the rotor (thus you get a superconducting BLDC machine). Much stronger than NdFeB, and as long as the cryocooler never shuts down, it never demagnetizes.

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:

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Reply to
Tim Williams

Of course the clutch disc in my Mustang, taken alone, has an even more remarkable ratio for the same reason--the actual power is being generated elsewhere.

Cheers

Phil Hobbs

Reply to
pcdhobbs

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Tesla EVs are unusual among EVs in that they use induction motors so there are no permanent magnets in the rotor - all the others do use rare earth magnets.

kevin

Reply to
kevin93

Barbers, salad stores or those stripping stolen cars?

But quit efficient.

And what in regards to electric motors?

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Jim Pennino
Reply to
jimp

Guess.

Depends on your definition of "efficient". 777s are quite efficient,

No OR, dumbshit. *AND*

Reply to
krw

Decline.

So are roller skates.

So what?

Or what in regards to electric motors?

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Jim Pennino
Reply to
jimp

motor design is very mature, there are other things in the chain that you can optomize

Reply to
Serg io

Actually early Tesla motors (and most electrical equipment of the time) were rather poorly designed and inefficient because the materials not being very good and the designs of magnetic circuits were very open and lossy.

Tesla invented a gas turbine with no blades of up to 95% efficiency which is the real winner over a typical gasoline engine.

Reply to
benj

Right. Which may give them some advantage in heat tolerance, because NdFeB has a relatively low Tc compared to other motor materials (iron, copper and polyimide).

A superconducting magnet would still preferably be "PM" (as I described), because of losses. I mean, the reason a squirrel-cage rotor moves in the first place, is entirely because of loss -- field gets trapped ("dragged") through it, and hence a change of angle generates torque. :)

(Hmm, you could still do it without magnetizing the (superconducting) rotor, it would just have to be constructed differently so that repulsion works instead. You'd have a "pushing" rather than a "pulling" motor. :) The slip frequency would of course still be zero.)

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

But ice skates are even better! So we just need this cryocooler (already present as described in the previous posts) to be able to cool down a sufficient part of the environment and do it fast enough before the car, I mean sleigh, arrives!

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Exactly.

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Jos
Reply to
Jos Bergervoet

So then why is their Tesla car electric?! O wait, you mean

*T*esla, not Tesla.. 
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Jos
Reply to
Jos Bergervoet

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