JBee

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So apparently as the Plaid has them the CT will have CRIMS.

Now as these are IM's at heart we are back to rotor hysteresis and copper losses. I wonder if these are responsible for the Plaids coming in at just under 400 mi and the cancellation of the Plaid plus.
CRIMs hey? Is that what they are officially called? So although they might have reduced efficiency compared to a PM they are better at freewheeling. It was also one of the reasons they mixed the two motor types with a PM and IM, simply beacuse of the overall low power required to propel a slippery EV. As well ss the whole rare earth magnet thing and especially cost of course.

Really by using hypermiling techniques whilst driving, like coasting, you can achieve better milage overall. Inertia is 100% efficient after all. Terrain mapping and preditive driving algorithms to achieve idealised momentum whilst transversing uneven terrain really does work (see Mercedes trucks). Another thing I'd like to see added is a constant power cruise control instead of constant speed.

A decade or so ago I was reading up about the different harmonics on a IM motor. At first these harmonics seem trivial, turns out they aren't. By using what they called a "chorus" ESC they were able to increase the efficiency by 3-4% not only putting them in range of a PM, but also reducing thermal loading. This meant they could use a chorus motor controller on any existing IM and increase the power output by 2-3x without any thermal issues. (Mechanical was something different)

So now I'm wondering if they're also using the same techniques together with square wire coil windings (and maybe hairpin coils) and a higher overall motor rpm (read higher peak power with even smaller motor) that requires a CF wrap to achieve near PM efficiency but with a IM.

One thing I noticed on the LR and plaid skateboard picture is that the motors all look the same size now, meaning its likely both front and rear motors are the same, with the Plaid just adding a third motor and a rearranged gearbox. I'm thinking that locking down the IM motor design to a common part across the range (incl. CT and semi) and streamlining manufacturing and costs the overall product actually improves profitability too.

At some point adding a few more battery cells to offset motor efficiency loss doesn't have a negative cost impact on range. Especially so if battery costs are appoaching $80kWh (4680s).

Theres also other areas where overall efficiency can be gained, in particular with aerodynamics, HVAC and tyres. It would be interesting to see a complete system sensitivity analysis. I think we're quickly approaching a period, probably within the next 5 years or so, where efficiency improvements will become more incremental and progressively harder to achieve.
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JBee

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The front motor is probably still the efficient model we've come to know and love.

-Crissa
I think every motor will be the same CRIM. No point in persuing PM if they can do it cheaper with their new IM. Modularisation of drivetrain components accross the entire vehicle range will lead to significant cost reductions.

The CT is getting more impressive now given it will share the Plaid drivetrain at nearly half the cost of a MS, despite probably having double the battery size in a much larger car. Value for money is 2x of any other Tesla IMHO.
 

ajdelange

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CRIMs hey? Is that what they are officially called?
Don't think so. That's me.

So although they might have reduced efficiency compared to a PM they are better at freewheeling. It was also one of the reasons they mixed the two motor types with a PM and IM, simply beacuse of the overall low power required to propel a slippery EV. As well ss the whole rare earth magnet thing and especially cost of course.
Any reading you do on it comes eventually to the rare earth thing. I'm sure that's the driver.


A decade or so ago I was reading up about the different harmonics on a IM motor. At first these harmonics seem trivial, turns out they aren't. By using what they called a "chorus" ESC they were able to increase the efficiency by 3-4% not only putting them in range of a PM, but also reducing thermal loading. This meant they could use a chorus motor controller on any existing IM and increase the power output by 2-3x without any thermal issues. (Mechanical was something different)
Yes indeed harmonics are a big deal. Some of them are negative sequence and really heat up the steel.


So now I'm wondering if they're also using the same techniques together with square wire coil windings (and maybe hairpin coils) and a higher overall motor rpm (read higher peak power with even smaller motor) that requires a CF wrap to achieve near PM efficiency but with a IM.
I don't know enough about the real nuances to be able to comment on harmonic reduction via space vector control but I think you can be sure that square wire or more probably hairpin winding technique will be employed. Musk specifically mentioned that the carbon wrapping allows a smaller gap which means less reluctance and more B for less H. Also these things can turn at higher speed (20,000 rpm) because the carbon wrap keeps them from flying apart.


One thing I noticed on the LR and plaid skateboard picture is that the motors all look the same size now, meaning its likely both front and rear motors are the same, with the Plaid just adding a third motor and a rearranged gearbox. I'm thinking that locking down the IM motor design to a common part across the range (incl. CT and semi) and streamlining manufacturing and costs the overall product actually improves profitability too.
I'm pretty sure all three will be the same and for the reasons you've given.


I think we're quickly approaching a period, probably within the next 5 years or so, where efficiency improvements will become more incremental and progressively harder to achieve.
I think we are already there.
 

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One thing that is going to be nice about the Crims is that they are going to quieter. The PMSRM's are actually pretty noisy in comparison to an IM.
 

ajdelange

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Someone posted a bit of video from inside a Rivian R1T. It has 4 PMSRMs and you can certainly hear them whining away.
 

ricinro

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maybe 600+ miles if you connect to Tesla trailer with extra battery pack...
 

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Much of limited access road driving these days involves speeding up and slowing down often, alas, to the point of having to come to a complete stop or crawl. In such cases intertial load is, if briefly, the biggest load. Also in hilly terrain you have to put potential (gravitional) energy into the load. That can be appreciable. But we have regen! Much of the inertial and potential energy we invest is returned to us if we can keep our feet off the friction brake pedal. Regen isn't 100% efficient so more weight does impose a penalty but it is a small one.

Now if you take your anvil collection up to your mountain cabin it's going to cost you kWh but, provided you take it home with you when you leave you will get most of that back. There is somewhere a quarry located at elevation. Their product (rocks) get hauled to a processing plant at lower elevation. The trucks are electric. They are never charged.
So do you recommend that when we go over a mountain pass that we stop at the top for a bit to load a large boulder (or a number of larger rocks) into the bed of our CT for the ride down? Unload the extra weight at the bottom.
 

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You need a dump load that turns the extra electrical power into heat.

On batteryless diesel-electric locomotives, they use the excess power to warm a pretty massive electric heating element on the locomotive, and they use a fan to evacuate the hot air. The railway folks call this "dynamic braking":


An EV without mechanical brakes would likely need a dump-load like this when driving in The Mountain West (USA) to prevent runaway vehicles on the multi-mile sections of steep downhill highway they have out there. Friction brakes can easily overheat on those sections, too, though -- anything that isn't captured by the regen system is going to end up as heat one way or another.

That said, I'd prefer to keep the friction brakes as a redundant safety system. My existing vehicle has multiple redundant braking systems which can all stop the vehicle (regen, 4-wheel hydraulic brakes, mechanical parking brake, and sometimes electronically controlled trailer brakes), and that's how I likes it. I've had to use the backup braking systems on vehicles on multiple occasions when I was younger and poorer, and so I value them quite a bit.
I hear what you are saying about mechanical brakes. And as someone else mentioned, mechanical friction brakes are going to be required for some time to come.

But...

Your description of why you want the mechanical brakes sounds very similar to other arguments I've heard in here about various other items (round steering wheels, side mirrors, etc). On those items too, the argument finally comes down to
that's how I likes it
No problem. That's what you likes.

I have a feeling though that over time there will be fewer and fewer people with this viewpoint.
 

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Not sure if its been mentioned yet but just today the thought occurred to me like what if that 610 miles is the total mileage rated for the battery pack and the 500+ is what will be normally accessible? Just a thought. I know Tesla has during times of emergency, like hurricanes and fires done an ATA adjustment and allowed more mileage out of the battery pack and then when all is good they go back and tone things back to normal. ?????
 

JBee

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I know theres a mine in Switzerland at the top of the mountain and they generate power from driving the fully loaded electric dump trucks down the hill and empty ones back up.

But typically coasting is always more efficient than regen, inertia is 100% efficient. In Germany they got the Model S down to 88Wh/km using techniques like that going 25 MPH.

We used that type of up and down flight profile for getting extra range out of our evtol UAVs. Thats beacuse increasing altitude at a higher throttle setting had better better motor and prop efficiency, on the way down the prop folds back to reduce drag too. Our 2.5kg "quadplane" can VTOL and fly +120km at 100kmh cruise on a single 4S 10Ah battery.
 

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... to load a large boulder (or a number of larger rocks) into the bed of our CT for the ride down?
Please don't do this. It's not generally legal. Leave the rocks in the mountains where they belong.

-Crissa

PS: No one wants to be a force of erosion, hastening the end of mountains as we know it!
 
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JBee

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Use water instead of rocks. Fill it up on top of the hill and then have remote release to let it out whilst driving along when you get down. Water will make its way down the hill anyway might as well use the hydro power... :p
 

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Please don't do this. It's not generally legal. Leave the rocks in the mountains where they belong.

-Crissa
I wasn't really planning to do it. Any rock that is large enough to make a difference is going to be too large for me to load anyway. Anything smaller is just going to be dirt or sand that would make a mess of my truck. Either answer would require some automated machinery to load (ie, not my back or arms) and basically defeat the purpose.

But I can certainly imagine some kids trying it out. Happy YouTube world we live in.
 

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Use water instead of rocks. Fill it up on top of the hill and then have remote release to let it out whilst driving along when you get down. Water will make its way down the hill anyway might as well use the hydro power... :p
With the climate controls in the back, perhaps we load the water, heat it up, and have ourselves a traveling hot tub.
 
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