Telsa Prepping New More Efficient Motors for Model S and X

[Drew Dowdell]

According to sources familiar with Tesla software, Tesla is preparing to update the Model S and Model X with new, more efficient motors.  Recent software updates have appeared that make reference to the new motors. 

The new motors with the codename "Raven", are permanent magnet reluctance motors as found in the Model 3. These motors have the benefit of pre-excitation from the magnets giving them an efficiency advantage. They also work to reduce the overall costs of the vehicle.  In the Model 3, the motors can achieve an efficiency rating higher than 97% compared to 93% on the Model S/X.   The difference in efficiency is even more marked in stop and go traffic where the Model 3 is much more efficient than the AC induction motors in the Models S and X. These upgrades could work out to a longer range and better performance for the pair. 

Tesla sales, though up year over year, have recently crashed down 31% from the previous quarter . While the timing of the release of these upgrades is not known, there are rumors that Tesla is planning a major interior refresh for the pair for 2020, so it could be matched with those updates.  Important timing when vehicles like the Porsche Taycan, Audi E-Tron , and Polestar 2 will be hitting the market over the next 18 months. 

 

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[balthazar]

Significant to mention WRT U.S. sales : Tesla's sales are down 61% vs. the previous quarter (77,525 > 30,600).
All other brands monthly/quarterly sales charts reported here are U.S. numbers, not global.

[G. David Felt]

Very cool to see they are upgrading the engines and interior, now to get them to get onto a competitive luxury level on the trim.

[loki]

from AC induction to DC motors?

that's the opposite of freight hauling loco's, but makes sense for "city" driving. AC motors have harder time moving from a standstill.

cool.

[dwightlooi]

(1) DC Motors are not better (or worse) than AC motors. They have different characteristics. DC motors have a linearly decreasing torque curve which starts at peak torque and falls to zero. AC motors start at part torque but reaches its peak output in the upper middle of its operating range. The problem with DC motors is that in order to have a usable output throughout the vehicle's operating speed range, it will be necessary to "over spec" the motor to have a wider operating rpm range and torque such that you'll still have usable torque at the mid and upper end. You will then artificially cap the torque output at low rpms to manage traction and/or protect the gear set. This "over specing" often negates, or reverses, the power density advantage of the DC Permanent Magnet Motor (PMM).

(2) Another issue with DC PMMs -- particularly large and powerful ones -- is that they are hard to assemble since you need to work against powerful magnetic forces to set the magnets in place. AC Induction motors are very easy to assemble as there are no magnetic forces to contend with until it is turned on.

(3) Economically, the PMM is reliant on Rare Earth metals for which the USA is not currently a major producer due to environmental and economic reasons. 80% of Rare Earth metals is produced by China today due to silly "Free Trade" and "unequal Trade" policies of successive US and western governments.

It is for reasons (2) and (3) that military and maritime applications have thus far shunned DC PMMs in favor of AIMs. Making small motors for RC cars is one thing; making 48,000 shp drive motors for a navy vessel is another.

Edited April 8, 2019 by dwightlooi