PMAC vs induction motor for model 3

[mspohr]

It seems every six months or so we get some guy who thinks he knows better than Tesla engineers and who is adamant that he is right. It looks like we have another flame war starting on this subject.
It's gotten to the point where this is a useless discussion.
I'm out... thanks for all the fish.

 

[Jeff N]

It's gotten to the point where this is a useless discussion.

I agree that people seem to be mostly talking past one another. One thing to keep in mindis that J. B. Straubel has strongky implied the Model 3's motor is new and not just a drop-in from the Model S. None of us know what that means right now.

 

[No2DinosaurFuel]

It seems every six months or so we get some guy who thinks he knows better than Tesla engineers and who is adamant that he is right. It looks like we have another flame war starting on this subject.
It's gotten to the point where this is a useless discussion.
I'm out... thanks for all the fish.

This discussion was brought in lights because of the bolt's efficiency, not because it is has been 6 months since some dissed tesla. And tesla themselves stated they didn't optimize for solely for range. So indeed my point of tesla not optimizing the drive train for range is correct.

Look, I am as much a tesla fan as the next but I am pointing out some possible non-optimized choices they made way back and now have to stick with it. I am sure there are engineers at tesla who wanted the PMAC for better range but because of other risk factors chose to stick with the induction motor.

This is not about who is right and who is wrong. Do a simple Google scholar search on PMAC vs induction motor and read the papers and anyone can easily conclude the same conclusion. If you don't like my summary go and read the papers yourselves which are NOT written by me.

Honestly I have not thought of this until I saw the bolt's efficiency numbers.

I was hoping some expert would chime in here. I know this is a tesla fan club but I was hoping to get some civil logical relevant discussion so I can learn something new. Maybe I missed something when I did my reseaech. I guess ill have to make due with those research papers for now.

 

[BluestarE3]

Hydrogen is more "efficient" than helium as far as providing better lift for a dirigible employing a given volume of gas. However, in the overall scheme of things, there may be reasons why hydrogen may not be the better choice even though it may excel in a single, isolated criterion.

 

[Red Sage]

This discussion was brought in lights because of the bolt's efficiency, not because it is has been 6 months since some dissed tesla. And tesla themselves stated they didn't optimize for solely for range. So indeed my point of tesla not optimizing the drive train for range is correct.

Look, I am as much a tesla fan as the next but I am pointing out some possible non-optimized choices they made way back and now have to stick with it. I am sure there are engineers at tesla who wanted the PMAC for better range but because of other risk factors chose to stick with the induction motor.

This is not about who is right and who is wrong. Do a simple Google scholar search on PMAC vs induction motor and read the papers and anyone can easily conclude the same conclusion. If you don't like my summary go and read the papers yourselves which are NOT written by me.

Honestly I have not thought of this until I saw the bolt's efficiency numbers.

I was hoping some expert would chime in here. I know this is a tesla fan club but I was hoping to get some civil logical relevant discussion so I can learn something new. Maybe I missed something when I did my reseaech. I guess ill have to make due with those research papers for now.

The singular choice that Tesla Motors made above all others is to make Performance a priority, rather than just a remote possibility. I believe that Tesla chose to set certain minimum thresholds for everything they considered a priority. Then they worked toward improving each aspect of their cars to be above those minimums and reach new maximums. That is an entirely different decision making process as compared to traditional automobile manufacturers, when it comes to electric vehicles. The efficiency you tout and the range it allows is the result of mediocrity in design, making the most of the worst, instead of pushing the best to its limits.

I think that what you have missed in your research is the goals and intentions of General Motors as opposed to Tesla Motors. One decided to make an 'OK' car that was electric. The other worked to build the best sports sedan in the world with electric drive at its heart from the ground up.

 

[William13]

To amplify on Red Sage's remarks, reduce, reuse, recycle. The mining of rare earth materials is limited to China currently. It is very toxic to the miners and environment. China recently threatened to cut off supplies to the rest of the world. Recycling is difficult currently.

These are very valid reasons to use ac induction motors where the efficiency is similar to rare earth motors. Many early skeptics of Tesla and EV in general complained inaccurately about the use of rare earth materials. Tesla should stick with AC induction motors.

 

[dhrivnak]

Remember the Bolt is a smaller lighter car so it WILL be more efficient. Case in point the Tesla Roadster using an AC induction motor by Tesla goes 240 miles on a 53 KWh battery. So more range on a smaller battery. Maybe Tesla does know what it is doing.

 

[No2DinosaurFuel]

Remember the Bolt is a smaller lighter car so it WILL be more efficient. Case in point the Tesla Roadster using an AC induction motor by Tesla goes 240 miles on a 53 KWh battery. So more range on a smaller battery. Maybe Tesla does know what it is doing.

1) that was using EPA old test. Not apples to apples comparison.
Model S Efficiency and Range.

2) the roadster is lighter than the bolt.
Chevy bolt: 1620kg
Roadster: 1305Kg

3) roadsters latest epa numbers: 105 mpge and 102 mpge. This is the sticker epa efficiency.
The New York Times > Automobiles > Image >

4) the roadster is more aerodynamic compared to the bolt. If it got less range than the bolt, then I would really worry.

 

[JeffK]

1) that was using EPA old test. Not apples to apples comparison.
Model S Efficiency and Range.

2) the roadster is lighter than the bolt.
Chevy bolt: 1620kg
Roadster: 1305Kg

3) roadsters latest epa numbers: 105 mpge and 102 mpge. This is the sticker epa efficiency.
The New York Times > Automobiles > Image >

4) the roadster is more aerodynamic compared to the bolt. If it got less range than the bolt, then I would really worry.

The Chevy bolt has a lower coefficient of drag than the Tesla Roadster, according to wikipedia, but the bolt does have more frontal area.

Why don't you find us an apples to apples comparison with the new P100D, something using a PMAC motor?

 

[No2DinosaurFuel]

The Chevy bolt has a lower coefficient of drag than the Tesla Roadster, according to wikipedia, but the bolt does have more frontal area.

Why don't you find us an apples to apples comparison with the new P100D, something using a PMAC motor?

Rimac one. But then we are talking about racing cars efficiency. Not really the same thing but interesting to compare at the high end between these two type of motors.

 

[3Victoria]

My impression is that aerodynamics does not make much difference to EPA ... it that true?

 

[Rashomon]

My impression is that aerodynamics does not make much difference to EPA ... it that true?

Not true. It doesn't have much effect on city rating, but it's a big part of the highway rating, even if the EPA test uses speeds that are lower than driven in most of the US currently.

I don't want to jump into a flame war, but . . . Most OEMs are electing to go with PMAC motors. In general, they're lighter, smaller, and more efficient over most of their operating map than induction motors. But . . . if you build a very high-performance vehicle that cruises at a small percentage of its peak power, induction motors may have an efficiency advantage. You have to have a vehicle use model and efficiency maps and then you can see which is better.

And motor technology is changing, with some new PMAC designs that can utilize amorphous stator "iron" and still be affordable to make, and with permanent magnets that have good performance with no to minimal rare earths. Efficiency and power density are improving. (Rare earths can be found outside China, btw, as was quickly discovered when China tried to act as a monopoly and boost the price; that didn't even work as well as OPEC oil supply control, and prices have collapsed since.) I expect most non-luxury e-cars to have performance more in line with an i3 or Chevrolet Bolt (more than competitive with ICE cars) and they'll almost certainly be fitted with PMAC motors. High performance cars from other makers (the Porsche project for instance) are also likely to use PMAC motors for power density reasons (size and weight) and to reduce cooling issues with sustained high power. But with multiple motors, they may elect to incorporate fast-acting clutches to decouple an axle during highway cruise to improve efficiency. A two-speed gear box would also help. We're just at the beginning of EV vehicle design (it feels like 1905 all over again), and the designs we see as best now may be obsolete in a decade.

 

[SageBrush]

The singular choice that Tesla Motors made above all others is to make Performance a priority, rather than just a remote possibility. I believe that Tesla chose to set certain minimum thresholds for everything they considered a priority.

I have the exact same impression.

Moreover, Tesla will soon crush the market with a sub 60 kWh EV that puts the Bolt to shame in highway range, at a profitable price point no higher than the Bolt. They want to use an AC induction motor ? Fine by me

I say this as someone who could really not care less about sports car level acceleration.

 

[Jayc]

But with multiple motors, they may elect to incorporate fast-acting clutches to decouple an axle during highway cruise to improve efficiency. A two-speed gear box would also help. We're just at the beginning of EV vehicle design (it feels like 1905 all over again), and the designs we see as best now may be obsolete in a decade.

Clutches, gearboxes, oh please no. Its a backwards move. I am anticipating reliability issues as is, can you imagine what would happen if the mechanicals become more complex.

Direct coupled AC induction motors controlled by Digital Signal Processing is the way forward IMO and Tesla has got it exactly right. Plus they have got to remain at the top of the game so they will definitely evaluate all the alternatives. And as we already know, they usually get it right the first time.

 

[TEG]

Induction Versus DC Brushless Motors

Might the Model 3 use a different motor technology? | Tesla

PM or Induction

Model 3 might use permanent magnet motors - Chinese Supplier • r/teslamotors

 

[SoCalGuy]

...?

 

[JeffK]

unfortunately the delivery event did not shed any light on this or what's new with these motors.

 

[BluestarE3]

Is there any reason to think (or even speculate) that the Model 3 might be different in this regard than its older siblings? More specifically, now that some actual specs have been published, is there anything new that would warrant reviving this rumor?

 

[03DSG]

If you check out the following certification documents the MS and MX are listed as using AC Induction motors while the M3 is listed as using a 3 Phase Permanent Magnet motor:

Model 3: https://www3.epa.gov/otaq/datafiles/CSI-HTSLV00.0L13.PDF

https://www3.epa.gov/otaq/datafiles/CSI-HTSLV00.0L1S.PDF
https://www3.epa.gov/otaq/datafiles/CSI-HTSLV00.0L2SV2.PDF
https://www3.epa.gov/otaq/datafiles/CSI-HTSLV00.0L2XV3.PDF

 

[JeffK]

If this is not a typo then it's directly in line with the rumors from last year about permanent magnets from China.

also... check out the "Charge Depleting Range (Actual miles)" (granted it's on a dyno so there's no wind resistance)

it also mentions SOC 78270 Wh so that solves that question