The Tesla Model 3's Modular Motors
Hello, I'm Professor John Kelly, and this is the WeberAuto YouTube channel. Today we're going to look at the Tesla Model 3, rear and front motors, and the equivalents that go in the Tesla Model Y, also, but let's begin with the rear motor for the Tesla Model 3. Now, as I've been exploring these different motors and drive units, on the Model 3 and reading about the Model Y motors, I've found some interesting things that I think you'll get a kick out of. So let's, let's take a look at these. First, the rear motor for the Tesla Model 3. As you may have seen in some other videos, used as a permanent magnet based rotor, you know, in other words, there's magnets inside of this, it's called an internal permanent magnet rotor. And this rotor has a shaft that
goes all the way through. This has some splines right here, that hook to an input shaft that is going to drive some other gears to make the vehicle move down the road. We've got some nice SK f bearings right here. And bearing on the other side. I'm going to put this rotor and input shaft into a mock up that me and my sharp assistant built. And let's take a look at how this thing is
connected together. And then we'll talk about what's common between all of these motors. So let me get this motor put in place first. Okay, as you can see, I've got it placed in some v blocks here. And we can just spin the, the rotor in the V blocks on its magnets. These, these bearings that it's spinning on are not ceramic bearings. These are some high quality, SKF bearings made for high
RPM because this motor also spins at a very high RPM, close to 19,000 RPM at its maximum vehicle speed on the performance version of the Model 3. But let's take a look at the other gears and components involved here. So this gear that we have right here, that's on the input shaft has 31 teeth, and it is going to drive another gear here on this counter shaft that has 81 teeth. So if we run that over here, put it right down in its v-block. Get the gears lined up, we have 31 teeth driving 81 teeth, and that gives us a gear ratio between those two of 2.6129. And the countershaft has another gear a smaller gear that has 24 teeth
on it, and it is going to drive our great big ring gear right here. This ring gear is the same diameter as the Model S ring gear that we looked at in previous videos 213 millimeters, it's a little bit wider than the front ring gear that used to be 40 millimeters on the Model S This one is 46. The rear one was 50 I believe. So it's the same diameter just a little bit narrower than the gear on the rear of the Model S and it uses these same gigantic bearings that the Model S used to handle all of the torque that is supplied to this differential case, the ring gear is held on with 16 bolts just like the other Model S's. This has an open differential style differential and so now we are going to set this differential case with ring gear with its 83 teeth down into the V blocks right there.
So now we have the 24 teeth of the counter gear driving the 83 teeth of the ring gear and that gives it a gear ratio of 3.4583 to one between the counter shaft and the ring gear. And then if we do an overall gear ratio between the electric motor shaft the input shaft, the counter gear, the small gear on the counter gear and the ring gear on the differential there, we end up with an overall gear ratio of nine Point 036321. Now I noticed in the owner's manual and on
Tesla's website for the Model 3, and the Model Y, they just list this as a nine to one gear ratio. But it's not nine to one that would be a hunting gear set, we want a non-hunting gear set, we don't want the same teeth coming in contact every nine revolutions. So we have a gear ratio of 9.0363 to one. So now, that means that I have to rotate this permanent magnet rotor 9.0363 rotations to get one revolution of our ring gear. Now the ring gear has side gears that connect to it. And that is where our axle CV shafts or half
shafts come in. Okay, the way I have this facing, this would be the rear of the car, this would be the front of the car. And there. Once again, as I spin the electric motor rotor, the permanent magnet rotor 9.0363 times our CV half shafts turn our hub and bearing assemblies and our tire and wheel assemblies, one revolution. So this motor spins a little over nine times faster than your tires. Okay, these are all the moving parts that are inside of the Tesla Model 3 rear drive unit, the rear electric motor. This is as I mentioned, a permanent
magnet rotor. So I have a permanent magnet right here, a neodymium magnet from a Toyota hybrid electric rotor. And I just want to show you, I'm not holding it here in my hand, that if I bring that magnet anywhere near this rotor for the Tesla, I can make the Tesla rotor rotate, just moving the magnet back and forth. These are very strong magnets. also kind of an interesting demonstration here. If we, if you watch this magnet in my hand, right here, if I turn changed directions, then it goes the other direction. That's because of all the different sets of magnetic poles that are in here. This is not an induction
motor, like they use in the front of the Model 3 and Model wide vehicles. So this is a permanent magnet based electric motor. And there's some really cool videos on how the design of this works and, and how the permanent magnets are aligned with other pieces of the rotor itself. But that, which is very
impressive, but check this out. What I think is really cool about the overall design of the front and rear drive units for the Tesla Model 3 and Model S is that they are actually modular, meaning we can you can change just a few pieces that make it a different motor. So if I take out this permanent magnet rotor right now, so I'm just going to lift it out. It's pretty heavy. I'm going to take off the input shaft, and I'm just going to set this rotor very carefully off to the side over here. And now we're going to change this entire unit to the front drive unit. So to change this to the front drive unit, I need to bring in a different rotor. This is a copper core, induction motor rotor, and
we're going to take that exact same input shaft that slid on to the end of our permanent magnet rotor over here for the rear drive unit. And we'll slide it right on to the induction motor for the front drive unit. And watch this. Set that right up in there. Align the bearings and now we have the front electric motor, the front drive unit, all the other parts are the same. How cool is that? The exact same part number so I've checked them all out. I've got both a front and a rear drive unit apart on the benches. Over here behind the camera,
and they have the exact same parts inside of them. So for manufacturing and costs that that's a really cool idea because it uses all these common components, you don't have to produce all these other components for different designs of axles, we have the exact same gear ratio on the front exact same number of gear teeth, exact same bearings, it's all the same internal pieces, we have the same oil pump the same oil filter the same oil cooler. The only thing that has to be different with the change in the rotor is a change in the inverter and the stator, this the part the big three phase stator that the rotor slides into. So, there are different power ratings for different electric motors on the Model 3, you can get a rear wheel drive only, which is the permanent magnet one, you can get a standard all-wheel drive, which is the permanent magnet in the rear and the induction motor in the front, you can get a performance all-wheel drive that has the permanent magnet in the rear and the induction motor in the front. But at
higher power, the internal guts are the same, but the inverter and the stator, either give it more power or not the inverter in this state are a matched set. By the way, I'll bring in the permanent magnet again from the rotor of a Toyota Prius and notice that it has no effect whatsoever on this rotor for the induction rotor for the front motor on the on the Model 3 and the Model Y. And then what's really cool is I was watching a video from Sandy Monroe several months ago about the Tesla Model Y front motor. And he pointed out that even a different rotor for the Model Y that did not have a copper core, it had an aluminum core. And so there are at least three different
rotors for this same gear combination here, which I suspect the aluminum rotor aluminum is not as good of a conductor as copper is. So that's probably the standard nonperformance version, front rotor and possibly the copper one is for the performance one only, I don't know for sure. But I that's what I that's what I suspect. So that's pretty cool. The common components of the rear motor, the front motor for the Tesla Model 3 and the Model Y, the part numbers for all of these motors in the Model 3 and the Model Y are identical for the rear motors, I can't find the part number of the front motor for the Model Y the drive unit. But I suspect from looking at the outside of the case
that it's the same as what we've got here just has that different aluminum rotor. Okay, let's take a look at the rest of the common components that you'll see in the Model 3 and Y rear and front motors. Okay, let's continue with what else is modular, what can what is almost interchangeable from one drive unit to the next on these on this modular design of these Tesla Model three and Model Y drive units. So I have an empty drive unit housing right here. And this drive unit. I've taken the gears out of I showed you those in the first
part of this video. But what I want you to see is that on this side of the drive unit, there's a big opening for the inverter and the inverter is the electronics that takes power on these two wires from our high voltage battery DC power changes it to AC power sends it out on these three terminals to these three cables. So in the drive unit, this bolts up right there. And this drive unit inverter bolts on to the side of the drive unit housing and it has a Part number on it this this drive unit inverter 1120970 dash 00 dash D and if you notice, right Here on this stator assembly, it has the exact same Part number on it. So
that means I believe that the inverter and the stator assembly are a matched set to deliver one of three different power and torque ratings available on the Model 3 in the Model Y, we have the rear wheel drive only version, we have the standard forward or all-wheel drive version. And then we have the performance all-wheel drive version. So there's three different sets of inverters. And stator assemblies is my theory. I've been able to find photographs on eBay of parts for sale from those different models. And there are
a whole bunch of different variations of these over the year since 2017, when the Model 3 first came out. So the inverter bolts up here on the one side, let me take that back off. But let me also go get the front inverter and bring it over. So here's the inverter for the front motor of the Tesla Model 3. And if you look at it, it looks
just like the one that we just took off and set right over here for the rear motor. But this rear motor is a permanent magnet rotor, the front motor has an induction motor. So the circuit board is a little bit different. Possibly the transistors are different that are used there. But I want you to see that this also bolts up to the exact same bolt pattern on the on the rear motor. So I'm not saying that you can swap parts around I'm just saying for Tesla, for the design to just have one size of casting one size of circuit board. It's and make it all interchangeable.
If you want to. Maybe if you wanted to switch from a standard range to a higher power version, you could swap out the inverter and the status assembly and make n rotor and make that happen and leave all of the internal gears as we saw there are the same for Model the Model. Alright, if we turn this drive unit housing around, we have this big round opening here. That round opening here is for our stator assembly, we have our three phase cables right here. They are going to go
into these three holes right here. This bolt pattern lines right up. There's a gasket or aluminum gasket that goes on there and bolts this and these three phase cables to the three copper terminals on the inverter. There's the access plug right here, this orange plug on the side, that is the bolts that connects the three phase cables to the inverter. So if you ever took an inverter off or a rotor or a stator off, you'd have to first take this cover off and take the bolts out so that we can separate the separate the two. Alright, the stator is
oil cooled. This takes a special ATF nine it's kind of a purple colored transmission fluid. There is no coolant running through this transmission. It's all oil cooled, and then it has a heat exchanger right here that this is the exact same part number heat exchanger that's on the front drive unit. This is the rear drive unit. But we have the transmission fluid pumped through the bottom here. We have coolant coming in the top here and an exchange exchanges heat to cool or warm the transmission fluid. Down here at the bottom of the
housing we have a place for a variable speed electric oil pump that fits in here. What's nice about the variable speed oil pump is that we're not reliant on a gear driven oil pump like we were on the Model S versions on the Model S the rotor bearings and all the input shaft bearings had to be kept cool and well lubricated especially at the higher RPMs at the higher vehicle speeds and that didn't happen until the vehicle speed was higher to drive that oil pump faster. Well on the Model 3, we have a variable speed electric oil pump that can pump coolant, or the transmission fluid, which is the coolant in this case through the bearings and not only that through the state or to cook to help cool the stator because it's, it's the transmission fluid that cools the state or assembly here. And so that is a huge advantage over a just a gear driven oil
pump. And then we also have an oil filter an external filter that screws on right here. And if there was ever a failure of any type, you can flush it out and change the filter. So we have the exact same part number for the oil pump and the oil filter and the heat exchanger for the rear motor as we do the front motor, the front drive unit. So a lot of common parts, the modular components
that make up the differences or makeup commonality between these now the differences are the cases themselves, these housings here are different. And the main reason for that is in the back of the car, the oil pump always sits at the lowest spot that have horizontal so that the fluid, the transmission fluid will go into the pump and then be pumped around. And the housing is pretty much parallel with the ground on the rear drive unit but on the front, it's tilted. It's kind of tilted like this. And so as you'll see when we get over
there, the oil pump is moved over to a different location. And so these housings are not interchangeable, but the bolt pattern for the inverter and the motor are the same, the bolt pattern for the heat exchanger is the same and the oil filter and the oil pump. Alright, let's look at the front drive unit next. Okay, on our front drive unit, you can see the oil pump housing with the with the transmission house transmission housing, mounted about like this pointing down in the vehicle. The oil pump is now towards the bottom
with our oil spin on oil filter next to it. So that's different than the rear, but it's still the exact same part numbers. These axle seals are the same part number. Here's our heat exchanger for the transmission fluid going through
to get cooled. And then if we come over here and look at the rotor, or the stator. Notice this stator is considerably shorter than the rear one and that's because the rotor isn't as long as the permanent magnet rotor on the rear motor either but this is an induction motor or stator assembly right here. And then here is our inverter for the front motor. The inverter is also liquid cooled has coolant with a coolant inlet and outlet over here is a coolant passage that goes through to cool the either the MOSFET or the IGBT transistors in there that run the current through the state or assembly here. This riff sorry this front stator will not bolt up to the rear housing. Even though the
bolt pattern is the same, the clocking the position of these three phase cables is different on the front than it is on the rear and so they are not interchangeable. And the reason for that is the placement of the stator and the cooling drain and feed versus the inverter with the transmission housing tilted has to be different than on the front one. But I want you to see that the part number here for this stator or this stator. Yeah, is 1120960 dash 00 dash
F and then it has its matching part number right here. It's upside down, but on the stator or the inverter assembly. So once again, these are a matched set these bolts Gather just like this. And it's my theory that the different levels
of power and torque come from different combinations of inverters and stators. Or maybe just the inverter is what's different and the stators are the same, I just don't know. But I, I wanted to show you what I thought was really cool in these drive units for the Model 3 and Y front and rear in that they have so many identical parts, which I think is a really cool design. Now I know I did not go through and deep deep detail on how these drive units are, how they work and how the oil flows through them and all that and I'll do a different video a little bit later showing you the internal pieces and the and the cooling and oil passages through the transmission, housing and so on. But this is just a quick semi quick video for my videos. Mine are usually long on the common components on these modular transmissions. So I hope you have enjoyed this video. We do
offer through this website here at the bottom of the screen and in the video description. Additional hybrid and electric vehicle training we have some online classes and a five day boot camp that we run four or five times a year. So if you're interested in additional education on hybrid and electric vehicles, you can sign up for that. Also, if you feel like you have benefited from this video or my other videos, please consider a donation to the automotive department here at Weber State University. There's a link at the bottom of the video description where you can donate directly to our department to help us obtain more components and cool things to show you in additional videos in the future. Thank you for watching.
2021-07-05 07:56
