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Forum Index : EV's : Tesla Motor Mystery

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yahoo2

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Joined: 05/04/2011
Location: Australia
Posts: 1166
Posted: 01:35am 06 Sep 2017
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Been watching the Tesla Model 3 roll-out with interest over the last few months. True to the companies lack of need to hype the car and only employees and company execs owning the few examples in the wild there are very few real details on what makes them tick.

I have been speculating about the design of the motor and am wondering if there is a secret or two tucked away in there. The EPA certification paperwork lists the motor generator as an AC 3 phase permanent magnet.

I have found this to be very curious, the rational logic is that this is one of two options,

1. EPA dumb mistake or miss communication or assumption on the paperwork and it is still an induction motor like the previous models.

2. it is actually a permanent magnet motor, this is a little odd given the history they have with the induction drive and the efforts they have gone to avoid fitting stonking big rare earth magnets in their kit in the past.

This leads me to think there is a third option.

If we look at the model S non performance 100D (D for dual motor) we see that the two motors are not designed the same even though they are physically the same size.

The rear motor is tweaked for power and the front motor is tweaked for better efficiency at cruising, the car can infinitely vary the power ratio between the two motors depending on throttle position and load etc.

Speculation on my part is that the new model 3 motor is a hybrid- a large reluctance motor for power and small modified synchronous motor for efficient cruising built into the one case. I have seen a photo that is supposedly showing the design cross-section of the Hyundai ionic motor and its weird shapes and laminate sections and that looks to me to be a possibly similar design.

The advantage of not having a large permanent magnet drive is that it avoids massive eddy currents while being driven at low power that waste energy.
The disadvantage of switched reluctance motors is that they make quite a lot of noise if they are not driven very precisely with some cunning electronics at low speeds.

The combination of the two could in theory give the best of both worlds. Could this be what we are seeing here?
I'm confused, no wait... maybe I'm not...
 
Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904
Posted: 12:07am 07 Sep 2017
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Thanks, now I learned something new again. I was not aware of this technology.

I wonder what they mean by that:" Stator coils have exceptionally short end-windings"
Klaus
 
yahoo2

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Joined: 05/04/2011
Location: Australia
Posts: 1166
Posted: 05:13am 07 Sep 2017
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The end winding is the loop that hangs out each end of the stators slots. Large generators at high loads will electromagnetically deflect the wires and start a resonance vibration that can rub through the insulation.

The guys that look after power station have nightmares about stator end winding vibration.

I guess these things have individual DC coils? that are easier to wind and fit than a 3 phase multipole stator so they can really tighten things up.

I was interested to read that car can modulate the coils without moving the rotor and use the heat to warm the cabin and condition the battery so they have done away with the resistive heater and avoided fitting a heat pump system in the car.
I'm confused, no wait... maybe I'm not...
 
domwild
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Joined: 16/12/2005
Location: Australia
Posts: 854
Posted: 09:32am 24 Apr 2019
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My son works for a Dysprosium mine SE of Broome. This rare earth is used in Tesla motors to reduce the loss of magnetism with heat, so there is one secret? My son believes before this trick they used coils and not permanent magnets??
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
Ralph2k6

Senior Member

Joined: 24/09/2017
Location: Australia
Posts: 129
Posted: 09:58am 24 Apr 2019
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Motor related.
Electronically commutated motors have come a long way. Look at modern brushless hand tools (not the cheap brands) even the cordless angle grinders can now replace the mains powered units with plenty of grunt,and not have the dangerous kick back if you get snagged.

Sorry if off topic
Ralph
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 3263
Posted: 04:20am 27 Apr 2019
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I watched a you-tube video recently about dismantling a Chevy Bolt motor.
This is a three phase rare earth motor/generator, electronically commutated.

And the guy in the video, Professor somebody or other, was saying how this particular motor was designed to be used across all Chevy electric vehicle platforms for a great many years to come. https://www.youtube.com/watch?v=APhRPSdmdmk
Its a great video, because he not only discusses all the design figures and details, he actually completely dismantles a whole drive transaxle and motor assembly piece by piece.Edited by Warpspeed 2019-04-28
Cheers, Tony.
 
Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904
Posted: 10:26am 27 Apr 2019
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Thanks for posting that link Tony, I just spent a very educational hour watching it.
Now I know what makes an electric car go, have always wondered what the motor looks like.
Klaus
 
domwild
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Joined: 16/12/2005
Location: Australia
Posts: 854
Posted: 10:11pm 27 Apr 2019
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A sad part of the story is the loss of the US federal subsidy to Tesla and Chevy as they each now have managed to produce more than 200,000 cars/year. This will stifle sales in the US and I can see it leading to Chinese dominance in the field. They also have a stranglehold on the rare earths required.

Because our air is much cleaner compared to the rest of the world, at least in WA without three-yearly car inspections!, our politicians do not see a need for any subsidy.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
BenandAmber
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Joined: 16/02/2019
Location: United States
Posts: 850
Posted: 05:33am 28 Apr 2019
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Video is a must-watch really appreciate the link
 
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