Why two motor types in CyberBeast?

JBee

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Thanks @JBee!
So if it gains this efficiency, why doesn't the Beast get longer range than the AWD? It's only heavier by the weight of one motor. The range difference doesn't make sense to me.
So the DM also has two different motors, being PM in the rear and induction in front. So it too can turn off the induction in the front.

But although these motors are turned off, they still need to be turned, as they are permanently connected to the wheels. The beast has two motors that need to be spun, and the DM just one. Together with the rest of their respective gearbox's and drivtrain.

That together with the extra mass cases more loses. Note the more efficient EV's become, the more sensitive they become to these variables. Also a more spirited drive style with the beast will also decrease range.

The DM is the best option anyway on multiple fronts.
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JBee

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Speculation here on the forum is that since FSD wasn't mentioned at the delivery that it's not ready in Cybertruck. That's just speculation so far I think. If it's true, I wonder how many hours of video Tesla will need in order for their AI to make FSD work. Another reason to hope for a steep ramp up in production.
FSD availability has little to do with camera placement, except for the addition of the nose camera that adds a new input the complete the field of veiw.

Essentially a variation of FSD will run on Optimus as well with less cameras.
 

tmeyer3

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So that's actually the other way around.

A Permanent Magnet motor has a "permanent" magnetic field which when rotating induces a current in the coil windings of the stator and causes a back EMF that tries to slow down the rotor. This also generates a current that needs to be dissipated, for example to charge the battery.

An induction motor does not have any permanent magnetic field, because the rotor uses windings that "induce" a magnetic field. Hence the name.

So in the case of the beast, the two rear motors are induction and are turned off during highway cruise and low power settings. This way the PM, that also has a higher efficiency than the induction motors, can drive the vehicle at the best possible efficiency. Like this the turning off is done without a clutch as well meaning less parts.

As for the price difference, the Beast has some other smaller extras like trim, but otherwise the premium is primarily for the extra motor. Which btw does torque vectoring in the rear as well, instead of using a diff lock.
Exactly this. I would just add more directly that the permanent magnet flux mentioned is what gives you regen braking, so you definitely want at least one permanent magnet motor.

I find it interesting that the induction motors were preferred for the Cyberbeast when the S Plaid was 100% permanent magnet. I'd love to see an interview on the engineering process for that dual induction beast motor.

Edit: be careful with "beast" on a phone, keeps autocorrecting to "breast"... Cyberbreast is just awkward
 
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GhostAndSkater

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A Permanent Magnet motor has a "permanent" magnetic field which when rotating induces a current in the coil windings of the stator and causes a back EMF that tries to slow down the rotor. This also generates a current that needs to be dissipated, for example to charge the battery.
This is slightly wrong, while induced currents on the copper windings are par of the losses on a permanent magnet motor, they are tiny because the individual cross section area of each wire is small

What really cause the losses is the steel laminations, hysteresis loses inside due to lossy process of magnetization and demagnetization as the motors spins results is heat. This is why the laminations are, well, laminations, this cut losses a lot but still is a big part, would be much worse if it was a solid piece

In a easy way to understand, if you took a permanent magnet brushless motor, spun it, then removed all the copper wires, and spun it again, the losses would be practically the same

You can even to this experiment at home, get a brushless motor from a old drone or RC vehicle, spin it by hand, open it and take all the copper out, and spin again, it will feel almost the same is terms of difficulty for you to spin and how long it takes to slow down
 

JBee

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This is slightly wrong, while induced currents on the copper windings are par of the losses on a permanent magnet motor, they are tiny because the individual cross section area of each wire is small

What really cause the losses is the steel laminations, hysteresis loses inside due to lossy process of magnetization and demagnetization as the motors spins results is heat. This is why the laminations are, well, laminations, this cut losses a lot but still is a big part, would be much worse if it was a solid piece

In a easy way to understand, if you took a permanent magnet brushless motor, spun it, then removed all the copper wires, and spun it again, the losses would be practically the same

You can even to this experiment at home, get a brushless motor from a old drone or RC vehicle, spin it by hand, open it and take all the copper out, and spin again, it will feel almost the same is terms of difficulty for you to spin and how long it takes to slow down
This is the case if you assume the motor inverter is not engaged at partial load to keep the motor spinning at cruise.

It would be pointless to have one motor on load and the other on regen whilst driving as this will only increase losses.
 


JBee

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Exactly this. I would just add more directly that the permanent magnet flux mentioned is what gives you regen braking, so you definitely want at least one permanent magnet motor.

I find it interesting that the induction motors were preferred for the Cyberbeast when the S Plaid was 100% permanent magnet. I'd love to see an interview on the engineering process for that dual induction beast motor.

Edit: be careful with "beast" on a phone, keeps autocorrecting to "breast"... Cyberbreast is just awkward
Induction motors regen just fine, they just have a different profile. Remember induction machines are the primary generation on your grid, thanks to the real Nikola Tesla.
 

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This is the case if you assume the motor inverter is not engaged at partial load to keep the motor spinning at cruise.

It would be pointless to have one motor on load and the other on regen whilst driving as this will only increase losses.
Even with the motor engaged

Back-EMF only limits your top speed (ignoring field weakening, which the motors definitely use), the losses on the copper wires are dependent only on the phase resistance and current going through them, but you need enough voltage on the phases to have left over voltage to induce the current you need for a given commanded torque
 

JBee

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Even with the motor engaged

Back-EMF only limits your top speed (ignoring field weakening, which the motors definitely use), the losses on the copper wires are dependent only on the phase resistance and current going through them, but you need enough voltage on the phases to have left over voltage to induce the current you need for a given commanded torque
So are you saying that the losses through the laminations are there regardless of if torque is commanded or not?
 

C T Rick

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Edit: be careful with "beast" on a phone, keeps autocorrecting to "breast"... Cyberbreast is just awkward
Are you sure about that. I was at the afterparty and met the Cyber Girls.

So my question is, Are the Cyber Girls from Outer Space ?
Or are the Cyber Girls Out of Space?


Did you notice my Cowboy Hat and Cowboy Boots?

Rick

Tesla Cybertruck Why two motor types in CyberBeast? IMG_9716
 

cvalue13

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On the note about the EPA application...it also states the battery pack is 150kw. When Elon said 123kw battery is that the current usable? Seems like a lot more range is unlockable in a future update.
the EOA docs reference to 150 was in Ah

At 812v converts To 122.4kWh
 


tmeyer3

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Induction motors regen just fine
I didn't know this! I need to go get more educated, thx! That's what I get for going comp sci and not paying attention in my EE classes 😂
 

tmeyer3

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Are you sure about that. I was at the afterparty and met the Cyber Girls.

So my question is, Are the Cyber Girls from Outer Space ?
Or are the Cyber Girls Out of Space?


Did you notice my Cowboy Hat and Cowboy Boots?

Rick

IMG_9716.jpg
I stand--firmly--corrected! 😂
 
 




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