Yikes ... Elon quote from the shareholders meeting...

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To be quite clear I hope and expect Tesla to continue using induction. However there are three reasons why I'm raising the possibility that one of the motors of the AWD Model 3 might use a PM motor:

1. I've seen reports of Tesla receiving shipments of permanent magnets. (Of course they could be for use in smaller accessory motors, i.e wiper motors, window motors, fan motors, etc.)

2. PM motors can be more efficient at lower power levels than AC induction and they can do full regen to zero RPM. These properties might make sense in the lower power front motor.

3. The previously mentioned statement that the second motor is a "different motor architecture". I would not classify a different RPM range as a "different motor architecture".

Frankly I had always dismissed the idea until I saw the "different motor architecture" statement. I can't imagine anyone familiar with motor design using it to describe just another variation of AC induction.
1. Show us the report.
2. There is no such thing as regen at zero speed. No motion = no energy = nothing to regen.
PM motors, by the laws of physics, cannot be more efficient at lower LOADS, read the article:
https://www.tesla.com/blog/induction-versus-dc-brushless-motors. If you still disagree, show us your source or your calculations.
3. Architecture does not necessarily mean different electrically. It could be different mechanically.
 

JRP3

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1. Show us the report.
http://rockstone-research.com/index.php/en/news/2125-Tesla-signs-permanent-magnet-supply-deal

Chinese listed magnetic material company Beijing Zhong Ke San Huan Hi-Tech Company (ZKSH) has announced the signing of an agreement to supply Tesla Motors with neodymium iron boron (NdFeB) magnets for the next three years.
2. There is no such thing as regen at zero speed. No motion = no energy = nothing to regen.
Really, that's the angle you're taking? I didn't say "at zero speed" I said "to zero RPM".

PM motors, by the laws of physics, cannot be more efficient at lower LOADS, read the article:
https://www.tesla.com/blog/induction-versus-dc-brushless-motors. If you still disagree, show us your source or your calculations.
Of course I've read that article many times. From that article:

One of the main differences is that much less rotor heat is generated with the DC brushless drive. Rotor cooling is easier and peak point efficiency is generally higher for this drive. The DC brushless drive can also operate at unity power factor, whereas the best power factor for the induction drive is about 85 percent. This means that the peak point energy efficiency for a DC brushless drive will typically be a few percentage points higher than for an induction drive.
Which means that if the front motor is PMDC and tuned so the peak point energy is say around 30-40mph it can provide increased efficiency in city driving, or if it's tuned for 65-75mph cruising speed it can provide increased efficiency in highway driving.

Additionally from the same article, regarding increased efficiency at lower power levels:

This advantage becomes increasingly important as performance is increased. With DC brushless, as machine size grows, the magnetic losses increase proportionately and part load efficiency drops. With induction, as machine size grows, losses do not necessarily grow. Thus, induction drives may be the favored approach where high-performance is desired; peak efficiency will be a little less than with DC brushless, but average efficiency may actually be better.
So for high power AC induction may have an advantage but not necessarily in lower power applications.
Also, from the article:

Still No Winner
My conclusion is that DC brushless drives will likely continue to dominate in the hybrid and coming plug-in hybrid markets, and that induction drives will likely maintain dominance for the high-performance pure electrics. The question is what will happen as hybrids become more electrically intensive and as their performance levels increase? The fact that so much of the hardware is common for both drives could mean that we will see induction and DC brushless live and work side by side during the coming golden era of hybrid and electric vehicles.
Possibly side by side as the second, lower power, front motor in a dual motor setup.


3. Architecture does not necessarily mean different electrically. It could be different mechanically.
It could but that would seem to be an odd description since mechanically all AC induction motors are quite similar.

Again, I'm not saying this is happening but there does seem to be good evidence that it's a possibility.
 

John

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JRP3: very interesting, thanks for sharing. Dated late 2016, so pretty fresh.
Hmmm....