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CTFP

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To be clear - there will still be a $39,990 RWD Cybertruck, but it will have 2 motors on the rear axle.
Might make sense for simplifying manufacturing and motor control if all versions have 2 motors in back:

GUESS:
'Tri motor' = Plaid powertrain
'Dual motor' = Raven powertrain (plus 2nd AC motor in back)*
'Single motor' = Model 3 RWD powertrain (plus 2nd DC motor in back)

* or maybe Model 3 AWD powertrain (plus 2nd DC motor in back) - might cost less to make but less energy efficient?
 
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ajdelange

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Do you understand the difference between an AC motor and a DC motor?
 

roncruiser

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Astute observation! The title bar at the top of this page shows a motor assembly. One of those cylinders contains the motor and the other the inverter - not a second motor.

You can put the inverter anywhere you want, of course, but you must run two wires to it from the battery and three wires from it to the motor. Copper is expensive and so, from that point of view, you want the inverter as close to the motor as possible. There are going to be I-squared R losses in the copper between the battery and stator wherever you put the inverter but the current from the inverter to the stator is high frequency (40 to 80 ? kHz) and that means additional losses from skin effect and wire inductance. Not to mention the radiation of noise up to a couple of MHz. Thus the smart thing to do is put the motor and generator in the same can. The efficiency gain by doing this might be small but as it confers other benefits as well it is clearly the way to go.

[Edit]Forgot to mention that the motor, inverter and gear box all generate heat and are on a common coolant loop. Having these components close to one another simplifies the plumbing for that.

Where Tesla really kills in efficiency is in the motor design. The PMSRM has no squirrel cage I^2R losses because it has no squirrel cage. It has no rotor hysteresis losses because the direction of the rotor flux does not reverse. I think I have seen 97% efficiency claimed for this motor as opposed to 93% for Tesla's older IM (don't take those numbers as gospel).
The skin effect and inductance is going to be insignificant but not eliminated at those frequencies even for a relatively short cable run length assuming they are using beefy enough conductors. Based on what I've seen so far, the Cu conductors they use in their motors are beefy enough.
 

ajdelange

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Not beefy enough that they don't get hot and waste energy. That's why eliminating rotor copper (and eliminating hysteresis in the rotor) makes the PMSRM appreciably more efficient than the induction motor. And easier to cool.
 
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CybrTrkOregon

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I have a hard time understanding this. So the AWD dual motor will have a single motor in the rr and a single in the front? Why would you put a different drive train in the rr of the dual then the rwd? Why would the AWD be 10k more with the same amount of motors? Makes no sense to me. Of course I am the same guy that want to buy a Hammerhead Eagle i Thrust
AWD has bigger battery capacity
 

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