New Semi Information

This video claims to have more current information on the Semi:

Highlights:

• Change to motor layout: One motor per Axel: Front/Middle/Rear.
• Only one charge port. (MCS only?)
• TACC currently active (The rest of AP not yet.)
• Extra cameras won't be needed on the trailer for AP usage.

 

[Olle]

Proposed new architecture:
Front axle: 1 efficiency optimized motor. 1 differential. 2x half shafts.

And two CV joints (and much more if they go with independent suspension.)
Additional drawbacks of the driven front axle

• Increased unsprung weight (some if independent suspension, huge if live axle)
• Increased turning radius due to CV joint limitations.

The only major benefit seems to be a little more regen but the mid and rear already take most of the weight so not that much
At a glance, it's hard to see how the new design is worth it.

I second this:

Help me understand, am I missing something here?

 

[TSemi]

No. There is no differential gearing. There is however, reduction gearing, that is a part of every Tesla drive unit. But that has nothing to do with a differential.

Professor John D. Kelly from Weber State University calls it a differential.

Start at 02:12

 

[Olle]

Professor John D. Kelly from Weber State University calls it a differential.

Start at 02:12

Because it is, in the Model S performance that Professor Kelly disassembled.

But there is no differential in the rear DU of a Plaid or the mid axle of the Semi from the Pepsi delivery event.

 

[TSemi]

But there is no differential in the rear DU of a Plaid or the mid axle of the Semi from the Pepsi delivery event.

In the video go to 02:44

 

[MP3Mike]

In the video go to 02:44

View attachment 917175

What's your point. That is a drive unit from a P90D, which has a differential. The rear of the Model S Plaid does not.

He does talk a lot about the gears in the "gear reduction unit", which is what it sounds like you are talking about, but that is not a differential.

 

[TSemi]

What's your point. That is a drive unit from a P90D, which has a differential. The rear of the Model S Plaid does not.

He does talk a lot about the gears in the "gear reduction unit", which is what it sounds like you are talking about, but that is not a differential.

He calls it a differential or "gear reduction unit".

 

[MP3Mike]

He calls it a differential or "gear reduction unit".

No, he doesn't. He does pick up the "final drive gear", the last gear in the "gear reduction unit" while mentioning the differential, because the differential is bolted to it. (It is the center part.)

 

[Rocky_H]

If something is a fixed reduction gear, that is basically the opposite of the part that is called "a differential". A fixed ratio reduction gear is very straight corresponding thing from a motor to an axle. A differential is a device that lets one drive apply force in a split way to two independently spinning axles, and can dynamically adjust the ratios even as the wheels change to spin at different rotational speeds (like in a curve, where the outer wheel is traveling farther).

Here's a video that shows why differentials are needed and how they are built and how they function. It's a really great explanation, because it builds up step by step from each concept as it gets more complex.

Anyway, just because some person in a video mistakenly used the term "differential" when referring to a fixed reduction gear, it doesn't make that correct.

 

[TSemi]

No, he doesn't. He does pick up the "final drive gear", the last gear in the "gear reduction unit" while mentioning the differential, because the differential is bolted to it. (It is the center part.)

He calls it a one-speed gear reduction unit

because the differential is bolted to it.

You are correct, MP3Mike.

 

[TSemi]

If something is a fixed reduction gear, that is basically the opposite of the part that is called "a differential". A fixed ratio reduction gear is very straight corresponding thing from a motor to an axle. A differential is a device that lets one drive apply force in a split way to two independently spinning axles, and can dynamically adjust the ratios even as the wheels change to spin at different rotational speeds (like in a curve, where the outer wheels is traveling farther).

Here's a video that shows why differentials are needed and how they are built and how they function. It's a really great explanation, because it builds up step by step from each concept as it gets more complex.

Anyway, just because some person in a video mistakenly used the term "differential" when referring to a fixed reduction gear, it doesn't make that correct.

In Munro's teardown video it does show the "reduction gears" at 04:29 and again they say there is no differential.

 

[MP3Mike]

He calls it a one-speed gear reduction unit

All of the gears make up the "gear reduction unit", which evere Tesla drive unit has, even the ones in the Plaid and the Semi. The differential is bolted to it for ones that need it.

You can review the Munro tear down of the Plaid rear motor if you want to see the reduction gears, and that there is no differential.

Though they don't really show everything. (But they specifically call out that there is no differential, but you can see the final drive gear there in the gear reduction portion.)

 

[TSemi]

All of the gears make up the "gear reduction unit", which evere Tesla drive unit has, even the ones in the Plaid and the Semi. The differential is bolted to it for ones that need it.

You can review the Munro tear down of the Plaid rear motor if you want to see the reduction gears, and that there is no differential.

Though they don't really show everything. (But they specifically call out that there is no differential, but you can see the final drive gear there in the gear reduction portion.)

The stators in future Tesla's will be hairpin and not the round wire as in the video. Interestingly VW and GM have using hairpin design for years.

 

[gsmith123]

How do you know this? The front and rear motors are both PMSM.

I forgot to answer this yesterday.

The Raven generation S & X used a Model 3/Y PM motor on the front and induction on the back (so they use the front motor for efficient cruising). I'm less familiar with the Plaid drivetrain. Anyone know what power distribution they use for highway cruising?

 

[TSemi]

The Raven generation S & X used a Model 3/Y PM motor on the front and induction on the back (so they use the front motor for efficient cruising)

The 2023 Model 3 and Y AWD uses an induction motor in the front.

 

[gsmith123]

The Raven generation S & X used a Model 3/Y PM motor on the front and induction on the back (so they use the front motor for efficient cruising)

The 2023 Model 3 AWD uses an induction motor in the front.

Yes, I'm well aware. Every front motor on every year of 3 and Y is induction.

I was pointing out that the Raven S & X are different and have a PM motor up front.

 

[TSemi]

was pointing out that the Raven S & X are different and have a PM motor up front.

Are you sure about that?

 

[TSemi]

Are you sure about that?

I used to keep up with that but have been a bit lax lately.

 

[gsmith123]

Yep!

Here's one source Tesla PMSR Motor (Raven) Explained and in the car itself in the additional info section it'll show PM front motor and induction rear. The power distribution at cruising speeds can be observed via OBD scanners. Don't have a link to a video of one of those handy though

 

[israndy]

Moderators, this thread needs to be renamed He Said She Said

 

[TSemi]

Yep!

Here's one source Tesla PMSR Motor (Raven) Explained and in the car itself in the additional info section it'll show PM front motor and induction rear. The power distribution at cruising speeds can be observed via OBD scanners. Don't have a link to a video of one of those handy though

I found this for 2019 Model S:

Interesting how Tesla has changed their motors and arrangement over the years.