Rotor is wrapped under high tension, you can't just slide a sleeve over after the fact. You also have no need for multiple directions because 99% of the load is hoop stress from centrifugal forces. Knitting it would actually just make it weaker because the threads would have sharp bends in them.

40 years engineering in big auto ICE, 20 years following EV development. Never thought Id see the day EVs would be allowed to reach their full potential let alone get a deep dive into the engineering. Thanks to Tesla for leading the vanguard and to Munro for letting us in on the detail. Done with skill full genuine enthusiasm transmitted on this brilliant channel, just the best 30 minutes.

The carbon fiber layer is wound extremely tightly to prevent expansion at 20,000rpm. Sandy's recommended method would not provide the pre-load compression that is needed to maintain tolerance.

On the carbon fiber winding, as close to radial as possible is the best. The filament winding industry calls this a “hoop” wind. With wet, or prepreg winding, the flow of the resin allows the individual fibers to nest into the previous layer’s surface. This makes the composite load up in unison as the rotor spins up. Using a woven “sock” will not match the efficiency of the hoop wound sleeve. As the woven fibers cross each other, the fiber is bent, or kinked, as it crosses every opposite angled fiber.

The carbon wrapped stator comes from rockets, let me explain. In rockets we use carbon over pressure vessels to make tanks, these are thin metal tank that are wrapped with thin strip of carbon fibre, these can take pressures of 5000 psi. With the magnets in the motors trying to push away from each other using carbon fibre wrap makes sense so you can hold in the magnets even tighter. If you use a woven cloth then the seem becomes a weak point of failure which would cause the motor to explode, wrapping is the olny way they could do it.

always smile when Sandy is happy about the engineering.

Rotor magnet skewing is nothing to do with physical torque pulsations that you can feel, because of the high effective rotor inertia and the high gear ratio between the rotor and the wheels, meaning the pulses, should they occur, happen far too rapidly to build into physical oscilationjs / vibrations. What the skewing actually does is make the backEMF of the machine more sinusoidal, meaning the 5th and 7th harmonic of the fundamental drive frequency is a lower magnitude. If you drive the machine with basic FOC, then the output votlage waveform is sinusiodal, but the backEMF is a modified sine (with the 5th & 7th harmonic components as mentioned) which causes a current ripple. That current ripple not only reduces motor and inverter efficiency, causes a high frequency EMC emissions, cause perturbations in the FOC current control, but also prevent one from running as close as possible to the average power switch current limit (because the peaks would cross the limit when they occur). This is especially an issue with very low inductance machines, ie high power / hgh speeds ones of course. What Tesla maybe doing is running with an active "feedforward" 5th and 7th harmonic cancelling voltage waveform, rather than relying on the axis current control to simply attempt to follow the backEMF. In effect, the inverter is actually now putting out a non-sinusoidal voltage waveform to match the non-sinusoidal waveform of machine! Do this, right, and you get higher efficiency, more power, and can run closer to the utlimate limits of the system, and you can run with a significantly stiffer current control loop too. The downside is your fundamental switching frequency needs to be high enough to be able to accurately synthesize this higher frequency voltage waveform, which requires faster and harder switching of your power elements, and a faster control loop to generate that waveform.

Sandy, the tolerances are too tight to be able to slide over a carbon overwrap knitted. That's why it has to be applied directly to the spool under tension. Especially as the shaft expands and contracts under load and heat.

Am I the only one already fired up for the Cybertruck series? Thanks Munro, appreciate all your team does for the community!

placing that converter had such a satisfying and consistent "clunk " when inserted to the various models.

THIS IS THE ONE BOYS AND GIRLS. THANK YOU SANDY!

I believe that explosive disconnect was a lot more impressive than you may have realized as it happened way too fast to appreciate fully. If you pause the video at 24:39 and then move though it frame by frame, then the explosion was bight and visible in exactly three frames. If you are working with a computer keyboard you can go forward or backward one frame at a time. After you pause a video, pressing the PERIOD key moves the video forward one frame at a time and the COMMA key moves it backward one frame at a time.

Pyro fuse on 2 motor phases is to avoid wheel lockup when the inverter fails catastrophically. On a standard vehicle, it would lockup 2 front, or 2 rear wheels symmetrically, but on the plaid it would lockup a single wheel, and send the car in a violent spin.

That inverter Phase bus bar pyro is VERY clever! It enables one to have a completely fail safe mode for a permanent magnet machine in the event of a loss of field control in the field weakening region (un-controlled regen ). It also cleverly uses HRC rated fuses to provide the final arc quenching, otherwise without those the severed section of bus bar would just arc across once opened by the pyro!

I'm so glad that Sandy and co could hangout with Tesla and SpaceX! I think that helps show Sandy how serious Elon is.... no other CEO is in the ballpark....

@16:15 a woven fabric doesn't make sense; the uni directional fibers are keeping it from expanding radially. they only need tension around the circumference, there's no bending forces on the rotor, nor any axial loads.

I disagree with Munro about the winding of carbon fibers. They are in the axis that matter, resisting centrifugal forces of the spinning rotor. Other direction would be wasted fibers. Furthermore, by winding the fibers they get pre-loaded and that way the rotor will withstand a lot of force before stretching out, while a jacket put on top will first stretch and then retain the magnet (maybe they could do a preloding by super cooling the rotor before insertion of the jacket ?)

There was a lot of talking about quality issues in the past - mainly about aesthetic ones - but when you look at the quality of the components and manufacturing methods used Tesla tends much more to the higher end than other EV manufacturers. And of course the "symphony" of arranging the components is of the highest quality :-)

Guys HANDS DOWN... this is just incredible explanation and a good insight attention to details

The carbon fiber overlap is wound under high tension to take stress off of the internal structure at high RPM. This is not easily achieved in biaxial or knitted sleeves. The CF overwrap also allows discontinuities in the magnet structure. Typically, the laminate has to hold everything together and that causes magnetic "short circuits" which reduce the available flux between the rotor and stator. B.T.W. "Tesla" is a unit of measure of magnetic field strength or flux density. It is only appropriate that their magnetic structures are strong!

best series on youtube atm

Two thoughts about the small laminations that are inserted between the magnets and the air gap: 1. Their main function is not to keep the magnets in place but to conduct magnetic flux. If you were to swap them out for something the same shape but of a non-magnetic material, the motor would lose most of its torque. 2. All of the small laminations have a hole in them. As this doesn't help conduct magnetic flux, my bet is that these are there to stick little pins through to hold them in place during the winding process. The processes would be in this order: Insert little laminations as well as rotor + magnets on a fixture --> have all the outer parts of the fixture (pins holding little laminations) move radially inwards so the little laminations touch the magnets --> put this whole fixture with all the parts onto the winding machine.

15:10 Wow, straight poles. This type of magnet configuration enables higher BEMF and torque output. Skewing the magnet poles (whether on rotor or stator) is only to reduce the resonance, but it also reduces torque output. The pulsing/jittering can become a problem, but because it is spinning so fast, those spikes will be perceived by our biological sensors as a "HUMMM" in RMS (root mean square). If it is spinning slowly, I'm sure they are close looping with field oriented controls.

Great job Ben. You've quickly become relaxed on camera.

Without Munro we wouldn't have this much details explain...!! Kudos man

I am an engineer ind the electronic industry (also worked in foundries, metal sheets etc.) for 20 years and a great fan of lean manufacturing - and I have to say that it is a great joy listen to you. Your are true experts with deep technical unterstanding. Bravo!

What I like about Munro is someone walking in on 6:35 he sees the camera and just smiles :)

Sandy - This is one of your greatest engineering videos. You and your company are just incredible!

About the carbon fiber: the only meaningful stress is hoop stress, so wouldn't having a unidirectional wrap be the strongest solution?

Wow, 25% improvement in torque just with the new star shaped laminate. Carbon fiber wound wrap, and the strongest magnets they have tested. Unlike conventional car motors, there is no offset. I can see many competitors buying the full report on this part.

Just watching this entire series from the time Sandy came on the scene has made me "engineering adjacent" so when I saw the inverter that could be put on there other vehicles I knew it was good engineering before Sandy said. You start to get a feel for it and it is NEVER BORING. Thanks so much for doing this, it's a lot of fun and I hope it will spark people going to school or looking to do something new to go into this field.

The strength of the rotor carbon fiber does not need to be lateral. Using fiber spool winding is the correct solution.

"For those who are not engineers, THIS is good engineering".

Thank you. I do think that Tesla has the wrapping part down well under control.

I think they got rid of the pulse with better control of the current with the inverter. The pulse is the action of the lines of rotor with those on the stator, if you control the current at the right time you can probably negate the pulse, a bit like they do with active noise cancellation. By getting rid of the source of the noise/vibration they probably get even more efficiency as they don’t need to offset the laminate anymore and they save money and complexity on the assembly line, genius!

THANKS4GIVING Another Engineering Symphony. KUDOS to the TESLA ENGINEERS and SUPPORTING TEAMS. These achievements are so dam exciting THE FUTURE UNFOLDS.

Nice breakdown and comparisons, beautiful engineering from Tesla and great analysis by Munro and associates.

Remember , mr munroe they wind the carbon under tension , a sleeve would be hard to tension

Another lesson in the fine art of education and entertainment for us who are inquisitive about the workings of new technology.

If I had a time machine, I would set the controls for an in person engineering / management discussion with Dr. Deming and our Sandy Monroe. Thanks for being you Sandy!

The tight winding puts the force on the carbon fiber not the epoxy to hold it. 787 fuselage is made in a similar way.

The first three minutes of this video says everything you need to know about Tesla. Thanks for pointing this important insight out.

Fascinating the kinds of innovations Tesla has made in only a short period of time.

Munro! Always on the cutting edge of information! Kudos!

1:00 Hearing the emphasis and passion in @munro live voice gives me joy. I love engineering and this channel is one of the best. Much respect to Munro & the crew.

Elon said the carbon sleeve has to be precisely woven ontop of the motor can’t be too lose or to tight. So I don’t think sandy’s idea would work, if I understood Sandy correctly

That was eye-opening as per usual. Of course, we were all waiting for the magnetic tricks in the rotor, and it didn't disappoint. But actually, what got to me first was the overall quality of the motor engineering. The castings, the finish on the bearing housings, the gears, the tolerances, it was all top notch quality and pushing the established boundaries.

17:30 Looks like Tesla is the new Sheriff in town 😉

When you work with strong permanent magnets like this, you should get a set of titanium tools. This is common for the folks who work on MRI machines. Just a suggestion...

I am surprised how much more strength they got of their magnets - the magnets are stronger - the rotor armature design make a stronger field - the rotor spin faster All together this will more than double the strength to weight ratio of the motor assembly and increase efficiency thus reducing the weight of the battery pack to get the same mileage. I hope their costing gets low enough to be able to put back all this tech into the model Y/3

I am a Tool and Die Maker + Engineer When Sandy Monroe talk's you should Listen... OUTSTANDING...

'THE INVERTER'_____ I was on my head when l saw that move from motor to motor!

This is the big one!!! Can't wait to watch!

his first walk thru with inverter seems so obvious, BUT gm ford and VW still don't get it. They seem to want to redesign everything every chance they get. 2 minutes in and its the same answer - buy more Tesla Stock.

As I remember Elon Musk described that the carbon sleeve requires certain tension to keep the rotor intact but not break the carbon fiber. The prefabricated sleeve might not work.

03:53 , beard guy expression says EVERYTHING abot the moustache guy's character. Priceless moment!!!

Thanks for showing us demonstrations alongside the explanations, I really enjoyed that!

Always awesome to watch you guys show how things work and how they’re made. I thought there was going to be a show and tell at the end of a new different way to wrap a stater

first 2 mins have brought tears of happiness to my eyes

“Any sufficiently advanced technology is indistinguishable from magic "

To this day it just amazes me how Tesla engineering can be so superior to Ford and GM. I know people that work at Ford in Dearborn and GM in Toledo, and they still think and talk about Tesla like its not going to make it and that Ford and GM will catch up shortly. Great Video as always thank you both.

Also, woven, ie non-unidirectional Carbon Fibre rotor wrap is a lot WEAKER, than the filament winding that they are doing for magnet retention. This is because with a filament wind more of you material is in the axis of the load (all the load is directed radially outwards by centripetal accel, there is no axial load) and because you can much more easily wind a single filament under tension. Tensile filament winding means the magnets are PRELOADED in compression when the machine isn't spinning , and only cross over into tension at some speed, this offset effectively raises the peak speed capability of the rotor by the offset compressive load! It's critical to have the thiniest magnet retention system possible, because the CF wrap is effectively adding to the air gap and hence reducing machine performance. Having a filament wind means you can run with a higher fibre to adhesive ratio, for the thinest possible layer.

Just got my laminates signed by Sandy, thank you so much. I don’t want to say what I do for a living but this is very aligned with my job. The laminates are just a keepsake for me. I watch all your videos and hope to meet you and the team one day!

G'Day from Australia. Thanks so much for doing the Rotor Laminate sale. I got mine in the mail already and very happy to have a small piece of history. Keep up the amazing work!

How can humans come up with such incredible engineering when some others just want to destroy humanity? Amazing video! Thank You Munro!!

Mind blowing inverter compatibility.

Mapping and compensation for motor cogging in software is common tech on high end industrial servo-motor controllers. (and the O-drive) The controller can do the mapping, a factory machine could do it, the map could be static if production is consistent enough, or it could be dynamic if they have a cheap way to correlate torque pulsing to cogging. (an accelerometer in the right spot and lots of DSP should be able to do it)

Thank you again Sandy and crew!!!! Fascinating!

Outstanding videos! Can’t thank you guys enough for sharing your knowledge with the world!

Has anyone noticed the inverter boards are roughly made in the shape of the continental USA?

2 mins into this and without a doubt this has been engineered by people that think about today, tomorrow and what has been done yesterday. This is my first look into the engineering of the Tesla or really any production EV for the consumer and I like what I see very much. I am excited to watch the rest.

Thank You Munro And Associates! Such a unique opportunity for all. You to lead us through new tech. Lucky to have this.

Haha the board for a sec looked like United States map

Pretty sure that the magnets are magnetic when they are installed. The process by which the magnets are magnetised would not work on the full assembly as the whole assembly would become one unified magnet; and that's assuming that you could create a pulse of that size, power and penetration.

Great show, enjoyed the breakdown and seeing parts that are interchangeable

the quality and workmanship is truly amazing, such smart engineering wow thank you sandy & Tesla

Defeating the need for a differential by having individually controlled computerized motors powering each rear wheel is probably the most genius engineering decision I’ve ever seen. Tesla engineers are absolutely brilliant!

9:34 Interesting how the shape of the inverter casting, being from a cross-section of the Model 3/Y motor housing, is now used in transverse section on the side of the Plaid motor housing, but the shape still fits the surrounding features.

Love seeing such forward thinking engineering. Thanks for sharing!

Hi Sandy, non pulsing of the magnetic field in a straight line of the rotor is no new phisics. It is about controlling the electrical current and therefore torque depending on exact rotor positions. You create a kind of overlay pattern to smooth the torque generation. It‘s an advanced control we used im machines for years. Great job you do! Regards from Germany Clemens

LOL, I have to read all the comments because there is so much information in them that a layman(me) would not know. Amazing stuff, amazing channel

Sandy and team, it's too late for me (I'm 38), but I'd imagine these videos you guys have been putting out have inspired a lot of older kids/young adults in to want to pursue mechanical engineering and engineering in general and how exciting it can be.

I was very attracted to this video - my magnetic personality helped. 1966, Army Aviation electronics school where I learned that the pole shoe magnets on a gasoline airplane engine's magneto were stacked laminates to reduce the eddie currents that caused radio interference. Fun times - could have used more rifle practice as I never rebuilt an Army plane's magneto, but missed a lot of shots in the beginning. Made it home, though, so no complaints.

brilliant, thanks Munro team

Are we all missing the point that the carbon fibers also hold the magnets and keepers from flying out?

My favorite video of yours was the Model Y vs. Mach-E Thermal comparison part 2, and my second favorite is whatever motor video I'm currently watching. I'm an EE but my skillset is miles away (networking chips) but the amount of detail you include in your videos is simply sublime. Thanks for making them.

its cool there is still so much room for innovation in a technology as mature as perm magnet motors.

What a privilege it is to get this kind of detailed breakdown of state of the art engines like this..

I was so ready for this one to be an hour

Love this channel! Sandy explains things so well, whats good and whats not - awesome.

love it. thank you, Sandy & Ben.

Judging by Sandy's enthusiasm, we're obviously getting to the juicy bits! Well Sandy, like you we're also sitting up and taking note! Many Thanks for making these video's for us to watch.

Was going to order a laminate but $150 is too high of a price. I bought one from the Y teardown for $50 and that seemed more reasonable considering I wanted to support the channel.

I would gladly pay for a Plaid Model 3 if Tesla were to build it. It doesn't sound like an incredible amount of retooling would be necessary to make it happen. Plenty of people would pay the premium.

I am not an engineer, but a bit of an energy nerd. And I have learned so much from these superb presentations. Thank you again, Sandy and crew!

New game! You drink every time Sandy says “I’ve never seen anything quite like this”

This motor explaination goes to show that just because you can dissassemble something does not mean you can explain why they did it that way. This is why you can duplicate it but not copy it. My company was famous for xray tube manufacture. They had the recipe (or so they thought). A lot of the senior staff retired and the output went to zero. They knew how make them, just lost the experience with the retired people. Many seniors got hired back.

At 13:35 they said they were going to show us some kind of sneak peek about the stator at the end of the video, did I miss it?

A calm, steady and focused on camera Sandy = BIG, AUDACIOUS surprises:) Team Sandy delivers again... just awesome content team and so thankful your company has chosen to share this way.. your team is absolutely inspiring the next generation of engineers.. or at a minimum annoying my daughter and her friends as I share your latest technology finding on my week to drive them to school:) (ps: yes, I bought one of those Sandy signed laminates.. can't wait for my week to drive the car pool!!)

The rotor laminations are super clever. Adding the carbon fiber wrap to increase the peak RPM of the motor forces the motor to have a large air gap and hurts efficiency. Internal PM magnet rotors usually use thin steel bridges for this task, but that short circuits some of the the magnetic field.