Telsa Prepping New More Efficient Motors for Model S and X

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.

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.

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.

(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.