People are paying many $ bills to get a teaching from this dude. We up here getting arguably a better experience then the class room in some ways, for free(ish). Awesome time we live in.
@WeberAuto I realize this video is a year old now and without checking all the comments, I don't know if someone already mentioned this but there are two different rotors for the LDU. The Base & Sport LDU's have different rotors. The Base rotor has less copper fill than the Sport rotor. The Sport rotor is completely full to the ends of the rotor. The Base rotor has a bit of a "bowl" where there's a void of copper. I think there's a lot of internet lore floating around that says both LDU motors "are the same" and that only the inverter is different but the rotors are definitely different. The LDU stators may or may not be the same. That's much harder to check since the stators are encapsulated.
Thank you Professor Kelly. You have made it possible for those of us in the developing world (I am in Ghana) to also learn and have an understanding of the new tech underneath the EV drivetrains. These videos are an absolute germ and it is my hope that we can all contribute to ensure its sustenance. Thank you once again.
Great videos. The high performance motors are induction machines to get around the problem of back EMF caused output power loss at higher speeds. Comes down to a tradeoff: Constant power over the full operational span at the cost of increased overall energy losses, or higher efficiency for decreased output power as speed increases? A magnet moving past a field creates a voltage proportional to the magnet strength and speed (back emf). A permanent magnet always has a strong magnetic field in the rotor. So, at some speed, the back emf exceeds the bus (battery) voltage and no more torque can be generated (flux weakening can help this, but eventually, no useful work can be done). But, because no rotor magnetization current is needed, PM based motors are much more efficient. None of the current in the motor is spent creating a magnetic field in the rotor. No rotor losses. For induction machines, the rotor acts as the secondary of a transformer. The current induced in the rotor (from the stator, primary) creates the rotor magnetic field that can then be used to create torque (via a process described as slip). This means the current in the rotor can be controlled. Because the current in the rotor can be controlled, the back emf can be controlled. Because the magnetic field in the rotor is controllable, constant mechanical power can be output until the variable frequency drive (VFD, converter) can no longer output higher frequencies. The penalty is rotor loses. Because there is current flowing in the rotor, induced by the stator, this power is lost in the form of rotor current (resistance of the rotor circuit). You have to pay, in terms of input electrical power, to create the rotor magnetization, therefore, less overall efficiency. But, constant mechanical power for the full operational frequency of the VFD. You can see this by spinning a motor by itself. A PM motor will generate a voltage as it freewheels, DMM between any two leads. (No current, because there's no circuit. Completing the circuit will make it a generator and the PM motor will act as a brake) An induction machine won't. (There will be a small residual voltage if it's an iron core, because of residual rotor margination, but not much) Applying a constant (DC) current to the windings of an induction machine (current limited power supply between one of the phase pairs, be sure to limit the power to something that won't damage the stator by too much heat), and spinning the rotor will make it feel like it turning thru peanut butter, the shaft will get stiffer as you try and spin it faster. Doing the same to a PM machine will make it 'cog' or make it unable to spin (by hand) at all. Be carefully at startup. It may turn very quickly with great force when current is first applied. If it's an IPM machine, there might be some cogging due to the motor saliency, e.g. the Nissan Leaf does this. I hope this was understandable and useful.
found this reply, very cool. was wondering if u know how induction motor can create regen. i just don't get how it can power the motor to induce field n receive current from motor at the same time...
Long video? Yes. But if you want to explain something right down to the details, time has to be taken. Thanks for another insightful and clearly explained bit of Tesla technique!
30:36 To heat cold batteries of not moving cars, the stators are powered with about 1-3 kW and are used as heat source when necessary. The stator heat will also heat up the lubrication fluids in the gear box.
This is only the case on Model 3 and Y, where Tesla puts DC current on the stator to use it as a heater. But also while driving (to a SuperCharger for preconditioning the battery) modulating some part DC current onto the AC current. The Model S and X have a seperate heating device, for heating the water by battery-DC.
As you drive down the road it puts the induction motor in 'torque sleep' mode (0 torque). It uses the PM motor only to drive the car. At some point in the application of the accelerator it starts using moth motors. I think torque sleep puts enough power to the induction motor so the output torque is 0 reducing drag and increasing efficiency.
@@justinmallaiz4549 I did not invent the term 'Torque Sleep' but read it in a Tesla document. I assume it has a purpose. Perhaps turning the motor ~9 times faster than the axles while the rotor is covered in oil creates/requires enough axle torque to require nulling out.
The use of induction motors as secondary motors has the advantage that they do not generate any voltage (and do not introduce any drag) when they are not used but driven from the wheels. The inverter simply does not feed any current or voltage to the stator in this case and thus introduces no energy losses.
Thank you (again!) professor for another illuminating session on the Tesla system. I know that there are many, many hours (days or weeks) of research and disassembly/re-assembly, editing and other real, unseen work that goes into your presentations. Thank you so much for these condensed, easy-to-understand tutorials on these very complex systems. Great nutrition for curious minds!
i can only imagine the hours that have gone in to clean all these parts. You are opening my eyes to the amazing engineering that goes into these cars. Who would know your front wheels are a different size than the back, I'm sure owners would just rotate the tires thinking them the same?
I'm very impressed with the level of knowledge transfer, and honesty when he says details about things he doesn't know. I wish when I had go to school, I had more professors like this that were driven for a quest for knowledge and not their ego or reputation. He also understands, as shown in these videos, that he could know everything in the world, but if he doesn't share it, that knowledge is useless. In his case, he shares what he knows, and honestly wants people to help him learn even more where he may not know something in as far a depth as he would like.
Permanent magnet motors are very efficient when operated close to max torque, but not so much on partial loads. That happens because the rotor magnetic field can't be reduced at will. Induction motors are different, the rotor field can be reduced or augmented at will, modifying the slip frequency. That means at small loads, and induction motor correctly controlled can be more efficient than a PM one. Same applies to externally excited motors, like the Renault Zoe one.
Model 3 perf ir mostly rear wheel driven in the winter (and thus unmistakably appears less stable on a slippery roads), model s vice-versa - feels primarily front wheel driven. In the wintery conditions ir is very obvious by vesicle behaviour. Thus your hypothesis that the more efficient motor is predominantly used in daily low performances scenarios agrees with winter driving observations. You are spot on.
Been watching since the 2nd Gen Volt videos. Now with a CyberTruck pre-order I’m enjoying the detailed dives into Tesla’s tech. Thank you so much for producing these!
Professor John Kelly, I was once an Electronics Tech at Weber State College, working for Sid Jensen back in 1969 through 1973. I wish I am younger to attend your classes on line or in person. I am a life long techie and find your teaching as excellent. The circular lecture hall was brand new in 1969. I did a Google Map of Weber State University, showing Engineering Technology Centre with what seems tobe new construction of Engineering Tech buildings.
@weberauto - To answer your question on how the car utilizes power distribution to the motors; Teslas primarily use the rear motor until throttle % or motor load reaches a certain limit, then it powers up the front motor as well. We can see this in ScanMyTesla, or any other OBD scanning tool while driving and logging. Cruising speeds and light load is always isolated to the rear motor only. Hard acceleration or when traction control is activated on the rear axle, is when the front motors engage.
Yes, your hypothesis was correct - the more efficient PM motor is used to supply most (all?) torque under certain conditions (e.g. highway cruising). Elon said this was how they are able to get increased range out of the AWD version of the S. It would be interesting to know more details on when this is done (I suspect it's not as often as possible, since the driven wheels affect the handling). Great series. Thanks for all the effort you put into these. I'd love to see more details about the power electronics (inverter) - maybe bring in an EE professor to go deep on the circuit-level design?
Do you have any idea how long that shaft grounding ring (18:48) will last? It seems that the conductive filaments get at least a bit of oil on them, from oil in the stator housing or just passing through from the bearing side, which should reduce friction and wear. Just curious to know if it's a periodically replaced part or not. Thanks for another excellent video Professor! Keep them coming!
I think such carbon filaments are quite wear resistant also in oiled condition as in dry contiditon. They should be designed for lifetime. But i am questioning if they maintain their function of shaftgrounding in dirty/oiled condition..
@Fürst Otto von Bismarck @weberauto - Aegis (has a/the patent) specs state 200,000 hours with "no theoretical RPM limit". I assume that this is under controlled test conditions with a clean shaft.
Yes it's the back motor thats there for main propulsion. Once you floor it, both of the motors engage instantly. Wish there was an option to lock into awd for snowy/icy conditions.
From the owner's manual of the 2020 Model S and Model 3 for the EU market, I can see that there are 4 versions of the PMa-SynRM: The first one is a 239 kW and 420 Nm motor with 350 V operating voltage, used in the single motor RWD Model 3 The second one is a 203 kW 330 Nm with 335 V operating voltage, used in the base dual motor AWD Model 3 The third one is a 219 kW 420 Nm with 320 V operating voltage, used in the Performance version of the Model 3 AWD The fourth and final one is a 205 kW 420 Nm with 320 V operating voltage, used in the entire Model S lineup from the base model to the Performance model (P100D)
Heads up, my 2022 model long range Model S has two permanent magnet motors, which produce 670hp combined. The performance model s top speed is 200 mph, the long range Model S is 149mph. Thank you kindly for your videos.
Prof. Kelly I didn't know that the electric parts of the motor are lubricated too, I always thought these motors are complete dry and I wondered how it's possible to cool them. Thank you for the great details you offer. Tesla uses only one permanent magnet motor, because if you have two of them, they give you resistance by being a generator, the iduction motor can run free without inducing any currents. So I guess, when the vehicle is cruising at constant speeds, it will just be powered by the high efficiency reluctant permanent magnet motor, while the induction motor is just idling. Greetings from Bavaria Germany, I bet you have german roots! ;)
There is an additional "feature" of the reluctance motors which is they suffer from torque flutter under very high power ramping - so they don't have the "kick" of the induction motors but they provide efficiency so are used exclusively under very low power conditions (cruising). So the reluctance motor + induction motor pairing provides the efficiency + torque ramping for the 2 different motors on the dual motor systems. I understand (please correct me if I am wrong) that only the rear induction motor is used for regenerative braking. This produces some undesirable effects in icy conditions requiring the more work on the anti-skid to correct this.
Great information, thank you! I have heard the same thing about not using the front motor for regenerative braking, but according to the ScanmyTesla app on our 2018 Model S P100D, both motors are used for regeneration with about 4 times more power generated in the front than the rear.
Tesla doesn't have reluctance motors. The permanent magnet motors produce some reluctance torque, but all PM motors with internal (rather than surface-mounted) magnets do that. Despite Musk's idiotic blathering, just think of these as PM motors.
@@brianb-p6586 It is defined in engineering terms as a PMSR, look it up in engineering publications. PM defines how the magnet field is generated, reluctance describes how the field dynamics are used to produce motion.
@@Tom55data I think you missed the point: the "S" in that acronym is "synchronous", not "switched" - they're very different. The problem isn't with the meaning of "reluctance". The other point, of course, is that all IPM motors can be considered IPMSR motors.
@@brianb-p6586 I know S is synchronous - that just mean the field is synchronous with the field it has nothing to do with how the field creates motion, only that the field is synchronous with the motion of the rotor - and R mean reluctance is a separate term meaning how the magnetic field is "latched" to the rotor to create motion.
Thank you for the informative video! I'm a bit surprised that Tesla would change the lubricant between revisions. I wonder if they were being cautious initially and decided that it wasn't necessary or whether they changed bearings in newer revisions that allowed them to go with a less expensive and lower quality lubricant.
Thank you. I wondered after shooting the video if the Dexron VI is for the 2019 and newer PM motor drive unit. Revision J is the one I am looking for now. Thanks for watching.
Thank you for the video of disassembling the front unit of Tesla. I have a question. 16:13 Conductive Brg. -> Rotor -> Ceramic Brg. -> AEGIS ring This will cause current to flow through the Conductive bearing. I think this is it, Ceramic Brg. -> Rotor -> Conductive Brg. -> AEGIS ring In this case, no current flows both Brg.s. Therefore, electrolytic corrosion does not occur. What dou you think?
Using Scan my Tesla OBD/CanBus tool on a 2018 MODEL 3 in most normal situations all the power goes to the rear motor. Power will flow to the front motor when accelerating harder. Even in snow power tends to go to the rear motor unless accelerating.
Phenomenal reverse engineering presentation on a variety of Tesla electric motors and gears. Thank you for creating these extremely informative technical video's.
Those helical teeth gears are used as they run quieter and wear less. That's because more than one tooth is engaged at any given time. Herringbone teeth take this one step further with opposing patterns that cancel out the side thrust. BobUK.
Simply invaluable, as an ME that wanted to learn more about how these systems work, this level of quality and no BS is a Jahsend. Regarding HX, I would assume counterflow, so if you know the oil flow direction you know the coolant probably flows the other way
I know that your time, painstaking effort and expertise is very much appreciated. This is so interesting and you present it so well - thank you Professor. I like the fact that, notwithstanding your great knowledge, this is also rather a journey of discovery for you - it accentuates your enthusiasm which is as infectious as it is genuine. May I wish you a very Merry Christmas.
I know I'm late to the party. In my 2023 Model Y, the rear motor (permanent magnet reluctance motor) is used almost exclusively in every day driving. The front motor is only used for a few seconds when accelerating from a stop or when a lot of power is needed. Same for regen. Almost all of regen deceleration is done by the rear motor, whit the front motor helping out just a little for short moments. This behavior makes the car most efficient as it rear drive unit is more efficient. There is an exception. When the ambient temperature is close to or below freezing, both motors will be used almost all the time. This helps getting more equal torque on all 4 wheels which helps in slippery conditions. In my 2015 dual motor Model S, the front and rear motor were both the small induction motors. The rear motor was used exclusively at speeds up to 60 mph. At 60 mph the car then switched to the front motor for higher speeds. If you pay attention, you can actually feel the shift. Both motors were used when you accelerate hard. Again, when the temperatures were close to freezing, the car switch to using both motors equally (exact 50/50 split in power for front and rear motor). I"m not sure why Tesla decided to using only the back motor at lower speeds and the front motor for higher speeds in the old Model S.
Permanent magnet motors always have a torque limit simply because one of the 2 magnetic fields is fixed strength aka limited. Induction motors as you pointed out you get more torque with more current, both fields increase. The 2 magnetic fields I'm referring to are the fixed (stater) and the spinning (rotor).
The reason the permanent magnet motors are more efficient is one of the magnetic fields is preexisting. For the induction motor you have to use power to make both of the fields.
Induction motors don't have any magnets, that can be possible to demagnetize and are generally considered to be the "toughest". I have fired up countless 3 phase motors from the junkyard and almost everyone of them, ran just fine, maybe new bearings is all. Try that with an engine sometime.
Another limit to consider, on both motors, is the field density limits of the electrical steel. At that point current at the stator or rotor just shoots up with no extra produced torque. That rise hopefully triggers inverter protections, or else by heat fries stator windings or rotor cage (never seen that), or demagnetize-bakes the PMs. Not so common in large motors, but you can see in low-grade e-bikes and such smaller apps.
Fantastic and exciting to see this--thank you. I wonder if there is an attitude like a steep hill at which the motor's lubricant pump gets starved for oil; this would probably be helpful for owners to know so they could avoid motor damage.
They are helical gears on the diff so it may be running 1 tooth at a time but thats 1 tooth in total. parts of more than 1 tooth will be in contact at the same time.
The smaller (tooth number) ring gear in the front drive unit is engineered to spin slightly faster than the rear drive unit to relieve chassis bind and allow proper handling with smooth and consistent steering characteristics of the vehicle.
How difficult would it to add Current Loops around the 3-phase power conductors in the motors of the Tesla? That and Voltage, RPM, would give most info needed about each drive motor performance at any instant. Current loops probably are a lot easier on less integrated system like Bolt.
38:20 I might be late to the party here: Tesla does use the rear and front motor differently depending on situation to improve range. Main parameters are: how heavy is your right foot when accelerating and travelling speed. Related material: ua-cam.com/video/vvw6k4ppUZU/v-deo.html
Hi John When you have a spur gear, yes one tooth is engaged but if it is a helix gear it depend on the angle and often the angle is so great that more then one tooth is engaged. Makes it a lot stronger and a lot more silence but the downside is axial pressure. I am almost sure that all gear wheels are ground. In that way you avoid debris from hardening in the oil. About the motor, that is a long long text... anyway the short story is to increase the current you must increase the voltages however that can't just be done, you have to take the frequency in to consideration. Here we are talking about Volt/Hz relationship and for the induction motor you also have the slip between the stator and rotor to account for, that is normal done by IR Compensation. anyway now it is starting to be a long story. I highly appreciate your videos. 🙏🙏🙏
@@WeberAuto Well I have made hobbing machines for many yers. I just finished producing a 9 Ton spur gear muddle 22 for a prototype win turbine so gears and AM and PM motor including servo drive is my speciality and electronic as well. Anyway I am sure that you already know. It is difficult to create a long fine detailed video on a complex matter such as this, even though you look at the video through more than once, small mistake will occur. I am astound over the brilliant videos you make. Respect and 🙏
You might want to check on your comment about the drive torque applied to the final drive gear, "one tooth at a time" this is true for straight cut gears but not helical cut gears. eg. 1.2 teeth contact at all times, a 20% increase.
Another amazing video Professor. Thank you for sharing with the world. I have the bluetooth dongle and ScanMyTesla app in my Model Y AWD. It shows that the front motor rarely gets used. Looking at the first log file that I could find it only used power starting at 30% accelerator. I had a Chevrolet Volt prior to the Tesla and during regen braking (in "low" gear as I usually drove) on icy roads the front tires would lose traction and cause some scary situations. After that experience I specifically wanted my next EV to be AWD to keep it from happening. Looking at the Tesla's log data it appears that it still only uses the rear motor for regen almost all of the time even though it has the ability to use the front for regen. The good news is that Tesla's software is smart enough to recognize when the regen is causing an unsafe situation and adjusts as I have never felt tires lose traction during regen braking. Tesla's regen braking on icy roads is more steady than the ABS when you need to use the mechanical brakes.
Excellent information! I just purchased the app and cable for our Model S. I look forward to gathering and sharing some data related to these motors. Thanks for watching
thanks Prof. Kelly for your and team's work on this video and for sharing it. I am so amazed at the the 17,000 RPM operating speed of the motor. I suppose that is what you can do when nothing reciprocates! Your videos about Tesla vehicles specifically also make it abundantly clear why they generally cost so much: it takes so many precision parts and so much design work! 😅 Happy Easter too 🌄
It is my understanding that the induction motor can generate more power on deceleration for the same reason they can be more powerful on acceleration. PM motors are limited by the strength of the magnets. Thanks for watching
Both types are more than capable enough for regenerative braking. The real issue is how much regen power the battery can handle - that's always limited to a lower value than discharge power.
Sir, all your videos are excellent. Can you please help us to understand on how two or more motors are controlled using a single accelerator input signal. How torque on demand from wheel and accelerator input are taken into controller and how the power is distributed to twin or more motors.
From what I've read researching ev transmissions rear will have a performance motor and one gear ratio. Front will have a permanent magnet and a different gear ratio more so for efficiency vs performance
If you watch some of Bjorn Nylands scanmytesla videos you'll see that the AWD Model 3s only use the rear (PM) motor the vast majority of the time (even for regen). Another reason to have an induction motor is that it can simply be switched off in situations like this. This wouldn't be possible if you had PM motors front and rear.
permanent magnets also don't like heat...induction motors are theoretically limited only by how hot the winding insulation can get before it starts to fail
And what is worse, their efficiency rolls off steeply at lower loads. A model S P85 uses 2.7kW going 32mph! Combined with the eddy currents going through the axle, they are the least suited type of motor for an EV. There is an alternative which is the line-start motor (LSPMSM) which still has a squirrel cage but also interior magnets, so it starts as an induction motor but runs as a syncronous PM motor at lower load. That way it preserves its peak torque but also has good low load efficieny, and it can still be driven by a simple VFD like an induction motor. I my opinion, when Tesla decided to scrap the 3 LR model with only one motor, they should instead have offered a version with a single LSPMSM motor instead!
@@Stefan_Dahn You did not understand what I wrote: The Octavalve has nothing to do with drive efficiency. However using a big induction motor, far too high power for an EV, results in piss poor efficiency at low loads. Even a model 3 with its PM motor, still only has 72% combined efficiency from the socket at 60 MPH (EPA). Had Tesla chosen smaller motors in their lineup, they would have made more efficient EVs! Tesla attracts the wrong kind of customers. They don't buy EVs to reduce their footprint, they simply don't care. Because then they would know that driving a Tesla in the US with its rather dirty grid emits as much CO2 as a compact car on diesel or gasoline! There exist EVs you can buy today that use around 160Wh/mi, half that of a any Tesla.
Ive watched a lot of your videos to learn about EV tech. If it helps me get a job in the future then I will definitely come back to make a donation. This content is worth much more than Netflix or Disney.
Thank you for your thorough presentation professor Kelly! I have two questions. 1. The first one is related to the ceramic bearings. From your presentation, it looks like one bearing (on the downside of the case is immersed in the cooled lubricant whilst the upper one is just sprayed with cooled lubricant. Would that make them function at different temperatures which eventually lead to premature wear of one of them? 2. What is the level of lubricant temperature inside the transmission considered normal? Is there a sensor or something to raise awareness of the possible overheating? Thank you very much!
Thank you! Sorry for the confusion, both bearings are on the same level, neither are submersed. I do not know the normal operating temperature of the lubricant.
@@WeberAuto Yes the bearings would get real hot if they were submerged in oil from all the friction. High speed low torque applications, like routers use an oil mist system for that very reason. I have a router that I put new bearings in 1985 that turns at 20,600 rpm, that still going strong with thousands of hours on it. It is lubed with a Bjuir oil mist unit that runs on 10 lbs of compressed air. Ceramic bearings have also been used in machine tool spindles for many years. On some spindles they use them because the balls are lighter and therefor have less centrifugal force, if they used the steel balls the bearing would be overloaded from the spindle speed alone with nothing left for any side loads at all.
I have a 2017 Tesla Model S P100D AWD and I have chosen to run square 21" 245/35/21 tires. I want to be able to rotate wheels/tires. I imagine that the beefier rear motor can handle the RPM difference caused by the decreased tire size, other than reduced traction from a narrower tire, and 7mm less rear ground clearance, what other problems could this create that I'm not aware of?
Thanks for great video. I enjoy every video from you. You compared two rotos with diameters lengths. Comparing the lengths should be usually effective active length. It means the lengths in it is the magnetic circuits. I don't know if you used the total length of the rotor with the both rings.
People are paying many $ bills to get a teaching from this dude. We up here getting arguably a better experience then the class room in some ways, for free(ish). Awesome time we live in.
You can tell that the man loves teaching :
WOW, Professor Kelly is a wealth of information. He does an excellent job of explaining the inner workings of Teslas. Great job Professor.
@WeberAuto I realize this video is a year old now and without checking all the comments, I don't know if someone already mentioned this but there are two different rotors for the LDU. The Base & Sport LDU's have different rotors. The Base rotor has less copper fill than the Sport rotor. The Sport rotor is completely full to the ends of the rotor. The Base rotor has a bit of a "bowl" where there's a void of copper. I think there's a lot of internet lore floating around that says both LDU motors "are the same" and that only the inverter is different but the rotors are definitely different. The LDU stators may or may not be the same. That's much harder to check since the stators are encapsulated.
If all teachers in the school system had been as good as you at explaining, .... Thank you professor
Wow, thanks! Thanks for watching!
Was waiting for this one! You are an excellent teacher!
Thank you very much
Thank you Professor Kelly. You have made it possible for those of us in the developing world (I am in Ghana) to also learn and have an understanding of the new tech underneath the EV drivetrains. These videos are an absolute germ and it is my hope that we can all contribute to ensure its sustenance. Thank you once again.
Thank you Professor Kelly for your efforts to keep us informed! They are much appreciated!
Glad you like them!
Another excellent presentation.
Thank you, professor !
You are very welcome. Thanks for watching
This guy is the absolute best. I have watched his amazing videos and was able to pass my L3. Thank you so much!
That is awesome! Congratulations on passing your ASE L3 exam
@@WeberAuto thank you, i learned so much from you and cant thank you enough. You are an amazing teacher
@@user-ru2hf1sg4e Thank you
Great videos.
The high performance motors are induction machines to get around the problem of back EMF caused output power loss at higher speeds.
Comes down to a tradeoff:
Constant power over the full operational span at the cost of increased overall energy losses, or higher efficiency for decreased output power as speed increases?
A magnet moving past a field creates a voltage proportional to the magnet strength and speed (back emf). A permanent magnet always has a strong magnetic field in the rotor. So, at some speed, the back emf exceeds the bus (battery) voltage and no more torque can be generated (flux weakening can help this, but eventually, no useful work can be done). But, because no rotor magnetization current is needed, PM based motors are much more efficient. None of the current in the motor is spent creating a magnetic field in the rotor. No rotor losses.
For induction machines, the rotor acts as the secondary of a transformer. The current induced in the rotor (from the stator, primary) creates the rotor magnetic field that can then be used to create torque (via a process described as slip). This means the current in the rotor can be controlled. Because the current in the rotor can be controlled, the back emf can be controlled. Because the magnetic field in the rotor is controllable, constant mechanical power can be output until the variable frequency drive (VFD, converter) can no longer output higher frequencies. The penalty is rotor loses. Because there is current flowing in the rotor, induced by the stator, this power is lost in the form of rotor current (resistance of the rotor circuit). You have to pay, in terms of input electrical power, to create the rotor magnetization, therefore, less overall efficiency. But, constant mechanical power for the full operational frequency of the VFD.
You can see this by spinning a motor by itself. A PM motor will generate a voltage as it freewheels, DMM between any two leads. (No current, because there's no circuit. Completing the circuit will make it a generator and the PM motor will act as a brake)
An induction machine won't. (There will be a small residual voltage if it's an iron core, because of residual rotor margination, but not much)
Applying a constant (DC) current to the windings of an induction machine (current limited power supply between one of the phase pairs, be sure to limit the power to something that won't damage the stator by too much heat), and spinning the rotor will make it feel like it turning thru peanut butter, the shaft will get stiffer as you try and spin it faster.
Doing the same to a PM machine will make it 'cog' or make it unable to spin (by hand) at all. Be carefully at startup. It may turn very quickly with great force when current is first applied.
If it's an IPM machine, there might be some cogging due to the motor saliency, e.g. the Nissan Leaf does this.
I hope this was understandable and useful.
found this reply, very cool. was wondering if u know how induction motor can create regen. i just don't get how it can power the motor to induce field n receive current from motor at the same time...
This is the most comprehensive video about tesla motor! Thank you very much!
Thanks for watching!
Long video? Yes. But if you want to explain something right down to the details, time has to be taken.
Thanks for another insightful and clearly explained bit of Tesla technique!
Thank you very much
That time flew by, really. Definitely didn't feel like a 46 minute video at all.
The best explanation of the Tesla motor set on Internet. Thank you
Wow, thanks!
30:36 To heat cold batteries of not moving cars, the stators are powered with about 1-3 kW and are used as heat source when necessary. The stator heat will also heat up the lubrication fluids in the gear box.
Great information, thank you
This is only the case on Model 3 and Y, where Tesla puts DC current on the stator to use it as a heater. But also while driving (to a SuperCharger for preconditioning the battery) modulating some part DC current onto the AC current. The Model S and X have a seperate heating device, for heating the water by battery-DC.
As you drive down the road it puts the induction motor in 'torque sleep' mode (0 torque). It uses the PM motor only to drive the car. At some point in the application of the accelerator it starts using moth motors.
I think torque sleep puts enough power to the induction motor so the output torque is 0 reducing drag and increasing efficiency.
That is what I suspected, thanks for the information
I don't think induction motors have any rolling drag ( besides bearings) .. The permanent magnet motor obviously do
@@justinmallaiz4549 I did not invent the term 'Torque Sleep' but read it in a Tesla document. I assume it has a purpose. Perhaps turning the motor ~9 times faster than the axles while the rotor is covered in oil creates/requires enough axle torque to require nulling out.
The use of induction motors as secondary motors has the advantage that they do not generate any voltage (and do not introduce any drag) when they are not used but driven from the wheels. The inverter simply does not feed any current or voltage to the stator in this case and thus introduces no energy losses.
Thank you (again!) professor for another illuminating session on the Tesla system.
I know that there are many, many hours (days or weeks) of research and disassembly/re-assembly, editing and other real, unseen work that goes into your presentations.
Thank you so much for these condensed, easy-to-understand tutorials on these very complex systems.
Great nutrition for curious minds!
i can only imagine the hours that have gone in to clean all these parts. You are opening my eyes to the amazing engineering that goes into these cars. Who would know your front wheels are a different size than the back, I'm sure owners would just rotate the tires thinking them the same?
Thanks for watching
I'm very impressed with the level of knowledge transfer, and honesty when he says details about things he doesn't know. I wish when I had go to school, I had more professors like this that were driven for a quest for knowledge and not their ego or reputation. He also understands, as shown in these videos, that he could know everything in the world, but if he doesn't share it, that knowledge is useless.
In his case, he shares what he knows, and honestly wants people to help him learn even more where he may not know something in as far a depth as he would like.
Thank you very much!
I thought those vehicle motors were much bigger.
259 hp on that little motor is amazing!
They are amazing! Thanks for watching
Permanent magnet motors are very efficient when operated close to max torque, but not so much on partial loads. That happens because the rotor magnetic field can't be reduced at will.
Induction motors are different, the rotor field can be reduced or augmented at will, modifying the slip frequency. That means at small loads, and induction motor correctly controlled can be more efficient than a PM one.
Same applies to externally excited motors, like the Renault Zoe one.
Great information, thank you!
Excellent video. I love seeing these parts exposed.
Glad you enjoyed it, Thanks for watching
Model 3 perf ir mostly rear wheel driven in the winter (and thus unmistakably appears less stable on a slippery roads), model s vice-versa - feels primarily front wheel driven. In the wintery conditions ir is very obvious by vesicle behaviour. Thus your hypothesis that the more efficient motor is predominantly used in daily low performances scenarios agrees with winter driving observations. You are spot on.
Thanks for the great information
Been watching since the 2nd Gen Volt videos. Now with a CyberTruck pre-order I’m enjoying the detailed dives into Tesla’s tech. Thank you so much for producing these!
Thanks for your long time support!
Incredible content. I can't believe this is free. You sir, are an amazing instructor.
Professor John Kelly, I was once an Electronics Tech at Weber State College, working for Sid Jensen back in 1969 through 1973. I wish I am younger to attend your classes on line or in person. I am a life long techie and find your teaching as excellent. The circular lecture hall was brand new in 1969.
I did a Google Map of Weber State University, showing Engineering Technology Centre with what seems tobe new construction of Engineering Tech buildings.
@weberauto - To answer your question on how the car utilizes power distribution to the motors; Teslas primarily use the rear motor until throttle % or motor load reaches a certain limit, then it powers up the front motor as well. We can see this in ScanMyTesla, or any other OBD scanning tool while driving and logging. Cruising speeds and light load is always isolated to the rear motor only. Hard acceleration or when traction control is activated on the rear axle, is when the front motors engage.
Great information, thank you!
Yes, your hypothesis was correct - the more efficient PM motor is used to supply most (all?) torque under certain conditions (e.g. highway cruising). Elon said this was how they are able to get increased range out of the AWD version of the S. It would be interesting to know more details on when this is done (I suspect it's not as often as possible, since the driven wheels affect the handling).
Great series. Thanks for all the effort you put into these. I'd love to see more details about the power electronics (inverter) - maybe bring in an EE professor to go deep on the circuit-level design?
Thank you and thanks for the suggestion
Most extra range is from putting more batteries in the car.
Do you have any idea how long that shaft grounding ring (18:48) will last? It seems that the conductive filaments get at least a bit of oil on them, from oil in the stator housing or just passing through from the bearing side, which should reduce friction and wear. Just curious to know if it's a periodically replaced part or not.
Thanks for another excellent video Professor! Keep them coming!
Good question. I do not know. Thanks for watching
I think such carbon filaments are quite wear resistant also in oiled condition as in dry contiditon. They should be designed for lifetime. But i am questioning if they maintain their function of shaftgrounding in dirty/oiled condition..
@Fürst Otto von Bismarck @weberauto - Aegis (has a/the patent) specs state 200,000 hours with "no theoretical RPM limit". I assume that this is under controlled test conditions with a clean shaft.
@@diyEVguy Thanks for the reply.
Thanks!
Thank you for your kind gift Udaya. I greatly appreciate it
You are an excellent person who has the ability to explain complex concepts in a captive dialogue. Thank you. From Mal R
You are very welcome
Have you already done the Model 3 front/rear motors? I looked, but couldn't find videos on those. Can't wait for them!!!!
Coming soon!
@@WeberAuto Can't wait! Videos should be a hit. There are way more of those cars out there with curious owners.
Tak!
Thank you René!
Yes it's the back motor thats there for main propulsion. Once you floor it, both of the motors engage instantly. Wish there was an option to lock into awd for snowy/icy conditions.
Great information, thank you
So glad you are doing these videos! Top notch quality. Are you still doing the one week class?
Yes I am. We have four more scheduled this year. See www.weber.edu/evtraining for the schedule
@@WeberAuto great! Thank you!
Excellent presentation professor
Glad you liked it!
So glad I found your channel! Thanks prof. Kelly for yet another great video
You are so welcome!
From the owner's manual of the 2020 Model S and Model 3 for the EU market, I can see that there are 4 versions of the PMa-SynRM:
The first one is a 239 kW and 420 Nm motor with 350 V operating voltage, used in the single motor RWD Model 3
The second one is a 203 kW 330 Nm with 335 V operating voltage, used in the base dual motor AWD Model 3
The third one is a 219 kW 420 Nm with 320 V operating voltage, used in the Performance version of the Model 3 AWD
The fourth and final one is a 205 kW 420 Nm with 320 V operating voltage, used in the entire Model S lineup from the base model to the Performance model (P100D)
Great information! Thanks for watching
@@WeberAuto thank you too for this video, you always bring great content!
Excellent Professor John -hope to join you soon in person
Heads up, my 2022 model long range Model S has two permanent magnet motors, which produce 670hp combined. The performance model s top speed is 200 mph, the long range Model S is 149mph. Thank you kindly for your videos.
my eyes are on a rav4 prime... but i still love learning about how teslas do what they do. thank you for sharing your knowledge!
These videos are amazing. The have so much information in them which you dont get normaly.
Glad you like them!
Prof. Kelly I didn't know that the electric parts of the motor are lubricated too, I always thought these motors are complete dry and I wondered how it's possible to cool them.
Thank you for the great details you offer.
Tesla uses only one permanent magnet motor, because if you have two of them, they give you resistance by being a generator, the iduction motor can run free without inducing any currents. So I guess, when the vehicle is cruising at constant speeds, it will just be powered by the high efficiency reluctant permanent magnet motor, while the induction motor is just idling.
Greetings from Bavaria Germany, I bet you have german roots! ;)
Thank you and thanks for the great information. I suspected that was the situation.
You can use two PM motors. Other AWD production EVs use PM for both axles.
There is an additional "feature" of the reluctance motors which is they suffer from torque flutter under very high power ramping - so they don't have the "kick" of the induction motors but they provide efficiency so are used exclusively under very low power conditions (cruising). So the reluctance motor + induction motor pairing provides the efficiency + torque ramping for the 2 different motors on the dual motor systems. I understand (please correct me if I am wrong) that only the rear induction motor is used for regenerative braking. This produces some undesirable effects in icy conditions requiring the more work on the anti-skid to correct this.
Great information, thank you! I have heard the same thing about not using the front motor for regenerative braking, but according to the ScanmyTesla app on our 2018 Model S P100D, both motors are used for regeneration with about 4 times more power generated in the front than the rear.
Tesla doesn't have reluctance motors. The permanent magnet motors produce some reluctance torque, but all PM motors with internal (rather than surface-mounted) magnets do that. Despite Musk's idiotic blathering, just think of these as PM motors.
@@brianb-p6586 It is defined in engineering terms as a PMSR, look it up in engineering publications. PM defines how the magnet field is generated, reluctance describes how the field dynamics are used to produce motion.
@@Tom55data I think you missed the point: the "S" in that acronym is "synchronous", not "switched" - they're very different. The problem isn't with the meaning of "reluctance". The other point, of course, is that all IPM motors can be considered IPMSR motors.
@@brianb-p6586 I know S is synchronous - that just mean the field is synchronous with the field it has nothing to do with how the field creates motion, only that the field is synchronous with the motion of the rotor - and R mean reluctance is a separate term meaning how the magnetic field is "latched" to the rotor to create motion.
Thank you for the informative video! I'm a bit surprised that Tesla would change the lubricant between revisions. I wonder if they were being cautious initially and decided that it wasn't necessary or whether they changed bearings in newer revisions that allowed them to go with a less expensive and lower quality lubricant.
Thank you. I wondered after shooting the video if the Dexron VI is for the 2019 and newer PM motor drive unit. Revision J is the one I am looking for now. Thanks for watching.
Thank you for the video of disassembling the front unit of Tesla.
I have a question.
16:13
Conductive Brg. -> Rotor -> Ceramic Brg. -> AEGIS ring
This will cause current to flow through the Conductive bearing.
I think this is it,
Ceramic Brg. -> Rotor -> Conductive Brg. -> AEGIS ring
In this case, no current flows both Brg.s.
Therefore, electrolytic corrosion does not occur.
What dou you think?
I was wondering why only 1 ceramic bearing, why not both?
Using Scan my Tesla OBD/CanBus tool on a 2018 MODEL 3 in most normal situations all the power goes to the rear motor. Power will flow to the front motor when accelerating harder. Even in snow power tends to go to the rear motor unless accelerating.
Great information, thank you!
Professor kelly, your tutorial is very well produced, it is excellent, thank you very much for sharing it, from Peru
My pleasure. Thanks for watching
I find these videos fascinating! Thank You
Thanks for watching!
Really good explanation of how the system is working thank you man for transfering tour knowledge
Phenomenal reverse engineering presentation on a variety of Tesla electric motors and gears. Thank you for creating these extremely informative technical video's.
Thank you very much
Those helical teeth gears are used as they run quieter and wear less. That's because more than one tooth is engaged at any given time. Herringbone teeth take this one step further with opposing patterns that cancel out the side thrust. BobUK.
Thank you sir for the video. I really admire your dedication.
So nice of you
Simply invaluable, as an ME that wanted to learn more about how these systems work, this level of quality and no BS is a Jahsend. Regarding HX, I would assume counterflow, so if you know the oil flow direction you know the coolant probably flows the other way
Thank you. Good point!
I know that your time, painstaking effort and expertise is very much appreciated. This is so interesting and you present it so well - thank you Professor. I like the fact that, notwithstanding your great knowledge, this is also rather a journey of discovery for you - it accentuates your enthusiasm which is as infectious as it is genuine. May I wish you a very Merry Christmas.
I know I'm late to the party. In my 2023 Model Y, the rear motor (permanent magnet reluctance motor) is used almost exclusively in every day driving. The front motor is only used for a few seconds when accelerating from a stop or when a lot of power is needed. Same for regen. Almost all of regen deceleration is done by the rear motor, whit the front motor helping out just a little for short moments. This behavior makes the car most efficient as it rear drive unit is more efficient. There is an exception. When the ambient temperature is close to or below freezing, both motors will be used almost all the time. This helps getting more equal torque on all 4 wheels which helps in slippery conditions.
In my 2015 dual motor Model S, the front and rear motor were both the small induction motors. The rear motor was used exclusively at speeds up to 60 mph. At 60 mph the car then switched to the front motor for higher speeds. If you pay attention, you can actually feel the shift. Both motors were used when you accelerate hard. Again, when the temperatures were close to freezing, the car switch to using both motors equally (exact 50/50 split in power for front and rear motor).
I"m not sure why Tesla decided to using only the back motor at lower speeds and the front motor for higher speeds in the old Model S.
Permanent magnet motors always have a torque limit simply because one of the 2 magnetic fields is fixed strength aka limited. Induction motors as you pointed out you get more torque with more current, both fields increase. The 2 magnetic fields I'm referring to are the fixed (stater) and the spinning (rotor).
The reason the permanent magnet motors are more efficient is one of the magnetic fields is preexisting. For the induction motor you have to use power to make both of the fields.
Good points, Thanks for the information and thanks for watching
Induction motors don't have any magnets, that can be possible to demagnetize and are generally considered to be the "toughest". I have fired up countless 3 phase motors from the junkyard and almost everyone of them, ran just fine, maybe new bearings is all. Try that with an engine sometime.
Another limit to consider, on both motors, is the field density limits of the electrical steel. At that point current at the stator or rotor just shoots up with no extra produced torque. That rise hopefully triggers inverter protections, or else by heat fries stator windings or rotor cage (never seen that), or demagnetize-bakes the PMs. Not so common in large motors, but you can see in low-grade e-bikes and such smaller apps.
@@jpinto3912 Thanks for the information!
Fantastic and exciting to see this--thank you. I wonder if there is an attitude like a steep hill at which the motor's lubricant pump gets starved for oil; this would probably be helpful for owners to know so they could avoid motor damage.
Great information from a great teacher
Thanks for watching
They are helical gears on the diff so it may be running 1 tooth at a time but thats 1 tooth in total. parts of more than 1 tooth will be in contact at the same time.
Yes, thank you, I was wrong about that.
The smaller (tooth number) ring gear in the front drive unit is engineered to spin slightly faster than the rear drive unit to relieve chassis bind and allow proper handling with smooth and consistent steering characteristics of the vehicle.
How difficult would it to add Current Loops around the 3-phase power conductors in the motors of the Tesla? That and Voltage, RPM, would give most info needed about each drive motor performance at any instant. Current loops probably are a lot easier on less integrated system like Bolt.
The inverter does monitor the three phase currents on EVs. Thanks for watching
38:20 I might be late to the party here: Tesla does use the rear and front motor differently depending on situation to improve range. Main parameters are: how heavy is your right foot when accelerating and travelling speed. Related material: ua-cam.com/video/vvw6k4ppUZU/v-deo.html
I would love to see you do a tear down with the new model 3, with the octo valve and heat pump. Great videos.
Coming soon! Thanks for watching
Very Educational....Keep up the Good Work.
Thanks, will do!
Hi John
When you have a spur gear, yes one tooth is engaged but if it is a helix gear it depend on the angle and often the angle is so great that more then one tooth is engaged. Makes it a lot stronger and a lot more silence but the downside is axial pressure. I am almost sure that all gear wheels are ground. In that way you avoid debris from hardening in the oil.
About the motor, that is a long long text... anyway the short story is to increase the current you must increase the voltages however that can't just be done, you have to take the frequency in to consideration. Here we are talking about Volt/Hz relationship and for the induction motor you also have the slip between the stator and rotor to account for, that is normal done by IR Compensation. anyway now it is starting to be a long story. I highly appreciate your videos. 🙏🙏🙏
Thanks for the information. I was wrong about the gear tooth on the helical gears.
@@WeberAuto Well I have made hobbing machines for many yers. I just finished producing a 9 Ton spur gear muddle 22 for a prototype win turbine so gears and AM and PM motor including servo drive is my speciality and electronic as well.
Anyway I am sure that you already know. It is difficult to create a long fine detailed video on a complex matter such as this, even though you look at the video through more than once, small mistake will occur.
I am astound over the brilliant videos you make. Respect and 🙏
@@A2an Thank you very much
I’m drooling, great detail, clear delivery and hella good vid!
Thanks for watching
You might want to check on your comment about the drive torque applied to the final drive gear, "one tooth at a time" this is true for straight cut gears but not helical cut gears. eg. 1.2 teeth contact at all times, a 20% increase.
Yes, I was wrong. Thank you
A man that can except his errors…is someone I will trust with the information given 😌
It monitors how much the accelerator pedal is pressed and decides if it will use the efficient motor, the more powerful rear one or both.
Thanks for watching
Woo, another amazing video! Thanks a lot Professor Kelly! Your explanation makes the complicated stuff easy to understand!
PM motors are used always to propel the car. IM motors usually coast. Bjorn nyland (teslabjorn) had videos about this subject.
Thanks for the info!
Another amazing video Professor. Thank you for sharing with the world.
I have the bluetooth dongle and ScanMyTesla app in my Model Y AWD. It shows that the front motor rarely gets used. Looking at the first log file that I could find it only used power starting at 30% accelerator.
I had a Chevrolet Volt prior to the Tesla and during regen braking (in "low" gear as I usually drove) on icy roads the front tires would lose traction and cause some scary situations. After that experience I specifically wanted my next EV to be AWD to keep it from happening. Looking at the Tesla's log data it appears that it still only uses the rear motor for regen almost all of the time even though it has the ability to use the front for regen. The good news is that Tesla's software is smart enough to recognize when the regen is causing an unsafe situation and adjusts as I have never felt tires lose traction during regen braking. Tesla's regen braking on icy roads is more steady than the ABS when you need to use the mechanical brakes.
Excellent information! I just purchased the app and cable for our Model S. I look forward to gathering and sharing some data related to these motors. Thanks for watching
Great video! Why is a smaller diameter tire used in the front as compared to the rear?
Hi. Could you please include the weight of each drive unit and include the info in your description? Thanks, great video.
Do you have a video on 2021 or newer Toyota Highlander Hybrid drive system? Thank You!
It is almost identical to the RAV4 Hybrid motor. See ua-cam.com/video/O61WihMRdjM/v-deo.html
Will you be doing a deep dive on the Model S Plaid motors?
I certainly hope so. Thanks for watching
thanks Prof. Kelly for your and team's work on this video and for sharing it.
I am so amazed at the the 17,000 RPM operating speed of the motor. I suppose that is what you can do when nothing reciprocates!
Your videos about Tesla vehicles specifically also make it abundantly clear why they generally cost so much: it takes so many precision parts and so much design work! 😅
Happy Easter too 🌄
Thank you, Happy Easter
does the coolant is non conductive completely or is there any threshold limit for that?
The proper coolant is non-conductive. Thanks for watching
How do Permanent magnet and induction motors compare when it comes to regenerative braking, I wonder. Anyone?
It is my understanding that the induction motor can generate more power on deceleration for the same reason they can be more powerful on acceleration. PM motors are limited by the strength of the magnets. Thanks for watching
@@WeberAuto Thanks! Your content is wonderful and appreciated.
Both types are more than capable enough for regenerative braking. The real issue is how much regen power the battery can handle - that's always limited to a lower value than discharge power.
Excellent video! Thank you so much. Any idea of the weights of the complete drive units?
Thank you, I do not know.
Sir, all your videos are excellent. Can you please help us to understand on how two or more motors are controlled using a single accelerator input signal. How torque on demand from wheel and accelerator input are taken into controller and how the power is distributed to twin or more motors.
The two motor controllers communicate with each other and other modules to keep everything synchronized as needed. Thanks for watching
Thanks for another great video. It's nice to get reliable, well researched information. Thanks for sharing.
Thanks for watching!
Hi - great video. I have same size tires on front and back on my winther 19". Summer is 21" with different sizes as you mention. All original.
From what I've read researching ev transmissions rear will have a performance motor and one gear ratio. Front will have a permanent magnet and a different gear ratio more so for efficiency vs performance
If you watch some of Bjorn Nylands scanmytesla videos you'll see that the AWD Model 3s only use the rear (PM) motor the vast majority of the time (even for regen). Another reason to have an induction motor is that it can simply be switched off in situations like this. This wouldn't be possible if you had PM motors front and rear.
Thanks, I just watched a few. Very interesting and it makes sense to only use the PM motor under most driving conditions.
permanent magnets also don't like heat...induction motors are theoretically limited only by how hot the winding insulation can get before it starts to fail
Thanks, that is true
The "SynRM" synchronous reluctance motor is the magnetically better design.
Induction motors have magnetic slip, and generate large heat.
Thanks for the information!
And what is worse, their efficiency rolls off steeply at lower loads. A model S P85 uses 2.7kW going 32mph! Combined with the eddy currents going through the axle, they are the least suited type of motor for an EV. There is an alternative which is the line-start motor (LSPMSM) which still has a squirrel cage but also interior magnets, so it starts as an induction motor but runs as a syncronous PM motor at lower load. That way it preserves its peak torque but also has good low load efficieny, and it can still be driven by a simple VFD like an induction motor. I my opinion, when Tesla decided to scrap the 3 LR model with only one motor, they should instead have offered a version with a single LSPMSM motor instead!
@@Tore_Lund Well, the MiC Model 3 has now a 60 kWh LFP battery and has a huge range and is extremly efficient with it's octovalve.
@@Stefan_Dahn You did not understand what I wrote: The Octavalve has nothing to do with drive efficiency. However using a big induction motor, far too high power for an EV, results in piss poor efficiency at low loads. Even a model 3 with its PM motor, still only has 72% combined efficiency from the socket at 60 MPH (EPA). Had Tesla chosen smaller motors in their lineup, they would have made more efficient EVs! Tesla attracts the wrong kind of customers. They don't buy EVs to reduce their footprint, they simply don't care. Because then they would know that driving a Tesla in the US with its rather dirty grid emits as much CO2 as a compact car on diesel or gasoline! There exist EVs you can buy today that use around 160Wh/mi, half that of a any Tesla.
Another Great video
I appreciate that
Thank you sir
Even with some mistake you still the greatest
Stay safe
Thanks 👍
What is the use of counter drive gear ?
Reduce gearbox size
Ive watched a lot of your videos to learn about EV tech. If it helps me get a job in the future then I will definitely come back to make a donation. This content is worth much more than Netflix or Disney.
Thank you for your thorough presentation professor Kelly!
I have two questions.
1. The first one is related to the ceramic bearings. From your presentation, it looks like one bearing (on the downside of the case is immersed in the cooled lubricant whilst the upper one is just sprayed with cooled lubricant. Would that make them function at different temperatures which eventually lead to premature wear of one of them?
2. What is the level of lubricant temperature inside the transmission considered normal? Is there a sensor or something to raise awareness of the possible overheating?
Thank you very much!
Thank you! Sorry for the confusion, both bearings are on the same level, neither are submersed. I do not know the normal operating temperature of the lubricant.
@@WeberAuto Ok. Thank you. I got it wrong it seems with the positioning of the bearings
@@WeberAuto Yes the bearings would get real hot if they were submerged in oil from all the friction. High speed low torque applications, like routers use an oil mist system for that very reason. I have a router that I put new bearings in 1985 that turns at 20,600 rpm, that still going strong with thousands of hours on it. It is lubed with a Bjuir oil mist unit that runs on 10 lbs of compressed air. Ceramic bearings have also been used in machine tool spindles for many years. On some spindles they use them because the balls are lighter and therefor have less centrifugal force, if they used the steel balls the bearing would be overloaded from the spindle speed alone with nothing left for any side loads at all.
@@WeberAuto Oh, forgot to tell you what a great job you do on all your videos, really enjoy watching them.
@@MrJohnnaz Thank you very much
I have a 2017 Tesla Model S P100D AWD and I have chosen to run square 21" 245/35/21 tires. I want to be able to rotate wheels/tires. I imagine that the beefier rear motor can handle the RPM difference caused by the decreased tire size, other than reduced traction from a narrower tire, and 7mm less rear ground clearance, what other problems could this create that I'm not aware of?
I have been told that there is a setting on the center display to tell the car what tires you have. Thanks for watching
Long video, but vveeerrryyy satisfying!
Thanks for your great effort and making this material publicly available! Excellent! Top marks, it i may! 😀
Thank you
謝謝！
Thank you Chin-Jen! I am very appreciative of your support
Thank you sir for fine instruction. Truly enjoyable presentation.
You are very welcome
Wow this was so good, learnt a lot huge Tesla fan and they have some amazing tech chemistry going on in their motors.
Thanks for watching
Thanks for great video. I enjoy every video from you. You compared two rotos with diameters lengths. Comparing the lengths should be usually effective active length. It means the lengths in it is the magnetic circuits. I don't know if you used the total length of the rotor with the both rings.
I realized after the video was published that I swapped the rotor dimensions of diameter and length. Sorry for the confusion.
@@WeberAuto I love your videos. Thank you so much.
Love your videos! I believe Tesla does impose a rear biased at low speeds and then transition to a front biased at higher speeds for efficiently.
Thank you and thanks for the info!