# Tesla Motor Varieties



## CfRP (Dec 17, 2019)

It would be so helpful to the conversion community if some of the more technically proficient members could put together some data regarding the different Tesla motors and their specs. 

It would be great to be able to get information like the difference between fwd units and rwd units and what/where application they'd work best in as transplants. 

I've tried searching for the tech bits, but I suck at the terminology so I just get unrelated nonsense google results. 

Thanks!


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## brian_ (Feb 7, 2017)

One challenge is that when people talk about "Tesla drive units", they sometimes assume that the discussion is about the original style of drive units in the Model S and X (which are the same for those two models). Those are the units with induction motors in two sizes, usually called the large drive unit (LDU) and small drive unit (SDU).

The LDU is used on at the rear. The SDU comes in two versions with the same motor and design of gears inside, but arranged differently in the case so that the front motor sits higher (to clear the front of the battery case).

A RWD Model S has one LDU at the rear.
A base AWD Model S had an SDU at each end.
A Performance AWD Model S has an SDU at the front and an LDU at the rear.

There seem to be different power ratings for what appear to be identical drive units, depending on what version of the car they came from, which is mostly a matter of battery size. The actual difference may be in the inverter, or perhaps just the programming of the controller... someone else presumably has that sorted out.

The Model 3 introduced completely new drive units, which are also used (perhaps with slight variations) in the Model Y. The Model 3 rear motor is a permanent magnet design, and the Model 3 front motor is an induction design. The Model 3 rear drive unit is now being used in some conversions, but this is recent.

One term which has caused a lot of confusion is "reluctance". Musk said at one point that the coming Model 3 would have a "switched reluctance motor", which is complete nonsense and was never true. There is a type of motor called that, but it's not used in cars. He probably meant to say - or would have said if he knew enough to - "synchronous reluctance motor". It isn't one of those, either, because they don't produce enough torque. It's really a permanent magnet (PM) motor; PM motors with the magnets embedded in the rotor (called interior permanent magnet or IPM) produce some of their torque due to the effect of rotor reluctance (a magnetic behavior), so some companies - mostly Tesla - like to list that as a feature, so they build awkward names such as "IPMSynR". It's really just PM. 

To make things a little more confusing, Tesla is now using drive units based on the one in the Model 3 in every other model, both existing (Model S) and proposed (CyberTruck, Roadster, even the Semi). The extreme "Plaid" version of the Model S has a rear drive unit which incorporates two motors which are based on the Model 3 motor (likely the permanent magnet motor)... but with the rotor wrapped in carbon fiber to hold it together at higher speed. I haven't heard of anyone using any of these newest units in a conversion yet, simply because they're too new.


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## shackf16 (Jun 13, 2021)

Brian gave a great overview of the motors themselves. Other considerations are where the motors are mounted relative to the axles. The Model 3 has the rear motor forward of the axles, while the Model S/X have the motor behind the axles. There are several folks who have reversed the Model S/X motors to put them forward of the axles (like the Model 3 setup) and run the motor in "reverse" as the main operating mode. This requires addressing the oiling/cooling system, but seems to be a viable long term solution. I have not heard of anyone doing the same with a Model 3 however. There are more options for controlling the Model S/X motors (both LDU and SDU) than for the Model 3, but I am sure the Model 3 market will grow based on how many have been produced and will ultimately end up in salvage yards.

As far as transplants go, I am using a full Model S rear suspension with SDU in the rear of a Ford Escape. One thing to be aware of with any type of transplant using the entire suspension is the width of the Model S - it's massive! I will be narrowing the rear subframe about 4 inches to fit within the normal track of the target vehicle. The Model 3 has a more reasonable track width and may be an easier transplant using the full suspension, but can be more awkward to fit due to the motor being forward of the differential. Also of note, the LDU setup in the Model S will not allow the subframe to be narrowed unless you separate the inverter from the motor side of things and relocate it. This means running additional coolant lines and makes packaging all of it much more challenging - and the packaging of the Tesla units combined with high power and efficiency are the reason they have been so popular with conversions!

Do you have a specific project you are planning to use a Tesla drive unit in?


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## brian_ (Feb 7, 2017)

One follow-up note...


brian_ said:


> ... Tesla is now using drive units based on the one in the Model 3 in every other model, both existing (Model S) and proposed (CyberTruck, Roadster, even the Semi). The extreme "Plaid" version of the Model S has a rear drive unit which incorporates two motors which are based on the Model 3 motor (likely the permanent magnet motor)... but with the rotor wrapped in carbon fiber to hold it together at higher speed.


After a review of published material regarding the Plaid motors - at the rear and maybe the front as well - it seems that Musk made a remark about the carbon fibre wrap being a challenge due to the difference in thermal expansion rate of materials including the copper in the rotor, which would imply that these are induction motors (using copper conductors as in the Model 3 front motor), rather than the widely assumed PM motor design:


Elon Musk (in Twitter) said:


> Carbon sleeve must put copper rotor in compression or it loosens at low temp due to differential thermal expansion.


Of course, this is Musk comment, which is not a reliable source of technical information. Even induction rotors are mostly iron, not any conductor (copper or aluminum), and the thermal expansion comment would be as applicable to iron as it would be to copper. The "copper" part was said in a live presentation and repeated in a tweet (suggesting confirmation), but Musk is not averse to repeating nonsense.


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## CfRP (Dec 17, 2019)

So would any of you more technical members be able to put together a table or something with different motors out of different teslas, both front and rear units, and some specs and usage applications. 

I have some questions too, like can the front drive units be used in a conversion? is it less efficient than the rear unit? 

thanks!


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## brian_ (Feb 7, 2017)

CfRP said:


> ... can the front drive units be used in a conversion? is it less efficient than the rear unit?


Assuming that you're talking about the original Model S/X units, then yes they can be used and there's no difference in efficiency because...


brian_ said:


> The SDU comes in two versions with the same motor and design of gears inside, but arranged differently in the case so that the front motor sits higher (to clear the front of the battery case).


If you're asking about Model 3 drive units...


brian_ said:


> The Model 3 introduced completely new drive units, which are also used (perhaps with slight variations) in the Model Y. The Model 3 rear motor is a permanent magnet design, and the Model 3 front motor is an induction design. The Model 3 rear drive unit is now being used in some conversions, but this is recent.


The front and rear Model 3 drive units use the same gears and the same diameter and design of stator (and inverters with mostly identical internals); however, 

they have different motor (rotor) types - induction front and PM rear, and
the front motor is shorter and less powerful than the rear motor.


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## CfRP (Dec 17, 2019)

Thanks for the info!

I found this information regarding the model 3 rear unit:


Input voltage (traction power)240-404V DC Input current (HV, peak)650A DCInput power (peak)220 kW (294 HP)Motor speed (max)18,000 RPMTorque (peak output)330 Nm (~243 ft/lb)Torque (regenerative braking, peak)115 NmOutput power (regenerative braking, peak)45 kWOutput current (regenerative braking, peak)140AInput power (continuous)30 kW Input power (15 minute)75 kW TransmissionSingle speed, 9.34:1, open differentialSystem efficiency (average)Approximately 92%Motor type3-phase AC inductionDry weight194 lbs (88 kg)

maybe its the other way around?
rear is induction, front is PM? 

I've got no clue, just trying to understand.


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## brian_ (Feb 7, 2017)

CfRP said:


> I found this information regarding the model 3 rear unit:
> 
> 
> Input voltage (traction power)240-404V DCInput current (HV, peak)650A DCInput power (peak)220 kW (294 HP)Motor speed (max)18,000 RPMTorque (peak output)330 Nm (~243 ft/lb)Torque (regenerative braking, peak)115 NmOutput power (regenerative braking, peak)45 kWOutput current (regenerative braking, peak)140AInput power (continuous)30 kWInput power (15 minute)75 kWTransmissionSingle speed, 9.34:1, open differentialSystem efficiency (average)Approximately 92%Motor type3-phase AC inductionDry weight194 lbs (88 kg)
> ...


The values generally look close for the Model 3 rear unit, except for the type. That table looks like a description of the original Model S AWD small rear drive unit (SDU), like what is posted by 057 Tech / HSR Motors. Their product listings provide this level of detail for each of the Model S/X induction motor drive units, but they don't have the Model 3/Y units, or the more recent Model S/X motors based on the same components as the Model 3/Y units.



CfRP said:


> So would any of you more technical members be able to put together a table or something with different motors out of different teslas, both front and rear units, and some specs and usage applications.


With the information from just this seller (057 Tech / HSR Motors), you could build a starting version of the table.

The Model 3 rear motor is absolutely PM (and the front is absolutely induction) - there are teardown videos showing the internal motor components, such as as _Weber Auto_: Tesla Model 3 and Y Modular Motors; that video might even have some of the desired data in it. Even the Wikipedia entry for the Model 3 confirms the motor types (and provides power ratings, with references).


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## brian_ (Feb 7, 2017)

CfRP said:


> Thanks for the info!
> 
> I found this information regarding the model 3 rear unit:
> 
> ...


In the specs for this induction motor, I think it's interesting to note the huge difference between the 220 kW peak power, the 75 kW possible for 15 minutes (such as a long climb up a mountain grade), and the 30 kW that can be continuously sustained. These Tesla induction motors are severely limited in continuous power by insufficient cooling of the motor's rotor.


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## brian_ (Feb 7, 2017)

You can also search the US DOE fuel economy website for all Tesla models and years of interest, select a few at a time for comparison, click the specs tab, and get front and rear motor power ratings for all of them. This site doesn't provide any other details (speeds, torque, gear reduction, induction vs. PM...), but at least it provides the power rating (which will be a maximum/peak value).


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## SuperV8 (Jan 22, 2020)

brian_ said:


> One follow-up note...
> 
> After a review of published material regarding the Plaid motors - at the rear and maybe the front as well - it seems that Musk made a remark about the carbon fibre wrap being a challenge due to the difference in thermal expansion rate of materials including the copper in the rotor, which would imply that these are induction motors (using copper conductors as in the Model 3 front motor), rather than the widely assumed PM motor design:
> 
> Of course, this is Musk comment, which is not a reliable source of technical information. Even induction rotors are mostly iron, not any conductor (copper or aluminum), and the thermal expansion comment would be as applicable to iron as it would be to copper. The "copper" part was said in a live presentation and repeated in a tweet (suggesting confirmation), but Musk is not averse to repeating nonsense.


This image from the Tesla presentation shows all three rotors are carbon wrapped, not just the rear, which means there may well me both PM & Induction motors which are carbon wrapped.
My 'guess' is this is purely down to the maximum speed.
Judging on the 200mph max speed and single gear ratio-
295 30/21 rear tyres are 710mm (21") dia using 9:1 gear ratio is 28,812 motor rpm at top speed.
9.5:1 gear ratio is 30,412 motor rpm
10:1 is 32,013 motor rpm

My best guess until Prof John Kelly takes one apart...









I notice Motortrend quote 20k rpm but this seems a bit low to me! unless they have changed the gear ratio from Tesla's usual 9.x:1? to 6.x:1! as 6:1 = 19,208 motor rpm at 200mph
Only 2k more than the 18k rpm old large performance rear motor doesn't seem like it warrants carbon sleeves!


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## brian_ (Feb 7, 2017)

The problem with press coverage of the Plaid motors - even from reputable automotive publications - is that they are working with almost no reference information. They only get press images and blurbs, with no technical detail and no technically competent person to interview. Even images such as the one above are suspect, because they are digital art rather than photographs of actual components - it could be showing entirely the wrong front rotor, for instance.We're all guessing, and some of the published guesses don't make sense.

I agree that we will have to wait for teardowns to see what is actually going on. I don't think anyone is giving Prof John Kelly a Plaid any time soon, but Munro is crowdfunding for one. Although Sandy Munro won't understand what he is looking at, at least we'll likely get a chance to see the rotors... likely torn apart.


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## SuperV8 (Jan 22, 2020)

Just noticed the 20,000rpm comes straight from Mr M's mouth! (but he does say maybe a bit more) This seems/feels too low to me to bother with carbon wrapping the rotors to hold them from expanding from centrifugal forces? vs 18000 for the previous large motor.

We know the wheel size/diameter - and we know the top speed of 200mph (eventually!) and from below I found the Plaid gear ratio is 7.5:1
So from that gives a maximum rotor RPM of 24,000 at 199.9mph

from here:

__
https://www.reddit.com/r/teslamotors/comments/nzgi8u


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## brian_ (Feb 7, 2017)

SuperV8 said:


> from here:
> 
> __
> https://www.reddit.com/r/teslamotors/comments/nzgi8u
> ...


I see the link to Reddit, but where did the Reddit poster get the table from? It's not anywhere I can find in the Tesla website (which changes at arbitrary times, and is not structured to deliver information), so it has - at this point - little credibility.

The 7.5:1 ratio is also a bit suspicious - it has likely been rounded from the actual value. That's not important mathematically (the rounding is less than a 1% change), but it suggests someone transcribing information between sources, perhaps not correctly. On the other hand, the road speed versus rotor speed calculations do make a 24,000 RPM rotor and ~7.5:1 gearing plausible.

I find it a bit amusing that they list "variable frequency drive". It's a bit like listing "round wheels"... yeah, it's going to have that.


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