[10.07.20]  Everything E-Torque

This page is everything 48V e-torque related 


Conclusion Image Directory

Some Project Background
This beautiful device exists as of late 2019. Its a motor, its liquid cooled, its got a built in inverter, its automotive grade and its presently fairly low cost on the used / surplus market. Just look at that thing. Its gorgeous. Have you purchased a hobby BLDC outrunner, and found that it exploded under load? Whats the half-life of hobbyking?
While this is no where near as lightweight as a 7kw outrunner, it is comically ruggedized and has an actual coolant jacket.
Behold the savior of electric go-karts, I bring you the e-torque. 
Its a gorgeous machine
The size of a modern alternator, but with extra magic inside. The widget on the far right is a spring loaded belt tensioner
Look at that built-in controller

Hot dang that's some gorgeous silicon.

What information about this thing exists [as of 10-2020] 
What vehicle is this contraption in?
  • Dodge Ram 1500 eTorque [2019/2020] [link]
  • Jeep Wrangler eTorque [2019/2020]  [link
This presentation from Continental: [external link] [local copy] has some interesting tidbits:

This is page 9,and you can glean a bit of what the nominal setup is. You have an induction motor tied directly to the engine, so no electric-only operation. Interestingly the photo shown has the motor and inverter separated, and looks like it was copied from an engineering diagram, as like I have no idea why phase resistance is included. Also what is a 12v Boardnet, did you mean 12v bus?
Here's some interesting bits. This is slide 12 from the above presentation

There's a 60mm and 40mm motor, both have similar operation parameters. The continuous rating is curious, 6kw in motor mode. Lets take a look at the vehicle to figure out why. Note the coolant temperature is 115C max, which may point to these being used in-line with engine radiator fluid. Having 100C 'coolant' for an electric motor seems inherently wrong, but alas this appears to be what this is designed for. Whats exciting is that it lists -40C coolant ratings, this is norminally to indicate it can survive, canada but, it indicates that there should be no issues with some very cold weather operation on an ice-vehicle. 
From this presentation [link], from the 2017 [European Conference on Nanoelectronics and Embedded Systems for Electric Mobility]  we get a bit of an internal view of the motor, not terribly detailed, but does give us a hint at performance. 14kw peak power [2 seconds] , 4.2kw continuous [1 hr] seems to differ from the previous slides, its very likely the test conditions were with 100C coolant, as 2 seconds is an incredibly short thermal operating window.
Lets do some more digging, Infineon makes a dev-board thats eer-ily similar to the built in controller, [link]. This thing is comically similar specification-wise to the 48v inverter on the back of the eTorque motor, and may be the dev-kit it's based off of. Lets take a look at the specs.
  • 12kW 500Arms (700A peak) Output
  • 105C liquid cooling capability
  • Design for integration with Motor
So, there's a few things of interest here, 105c liquid cooling: 105c coolant is not coolant, its just the nominal radiator fluid temperature of an ICE engine. Its doubtful that an automoitive group would use an array of electrolytics, for a high temperature application, but its a reasonable place to work from. Interestingly this module is available from digikey [link], for a whopping $869.54.
Here's an interesting app-note on this thing [link] [local copy]
Can we glean any information about 48v hybrids from standards?
Enter ISO 21780, this is the 48v vehicle supply specification. I purchased a 2019 vintage draft, while the motor was likely born after this motor was manufactured, but lets dig in anyway. The ISO bodies are incredibly protective of their standards, which for whatever reason cost money. Relevant Ycombinator Post:

 So unfortunatley I have to be vague here, from what I can tell, small excerpts are ok. Did you know the bus operating range is defined in an ISO spec?  Seriously, 60-58v is the upper overvoltage range, 58-54 is the overvoltage range, 54-52 is the 'you are entering overvoltage range' 52-36 is normal voltage range, 36-31 is the 'you are entering low voltage range' 31-24v is the undervoltage range and 24-0v is the undervoltage limit.  This is annoying, I really want to share this specification. Other interesting tidbits, at 40C, the quiescent current must be <0.1mA for the device under test. 
Does the 2020 copy show anything useful?
I had put in a library request for a copy, and while it took a few days, it appeared.
Interesting video about the e-torque system on the ram 1500 [link].
  • The stop-start feature is demo'd around 2min and 40 seconds in. 

So lets start digging public information which may help us find out at least the pinout of this monster.
Thanks to the Jeep JL forums [link]  there's some interesting wiring diagrams. Unfortunately, this vehicle is a modern monster of sensors. 

So i did the thing, I bought the actual service manual. 200$ for a manual for a vehicle I do not own. Neat. Even more curious, this is a physical flash drive, so lets see what actually shows up. The delivery window is ~two weeks, so either it is a hefty flash drive or its coming to Boston via a boat. 

Hardware Tear-down
Lets start out with the first surplus motor, this is basically exactly as it came from ebay, with two caps added to the coolant line. Note the pulley tensioner is in its 'relaxed' state and otherwise has a coiled spring for applying tension.
the back
The small plate cover comes off with a few torx screws, there is a perimiter seal of some kind of rubberized adhesive.
Zooming in

Zoomed in we can get a better idea of what is going on, The motor phase connections pop out of the motor case and mate to the motor controls power board with a weldment. This may be an ultrasonic weld, its too clean to be a resistance weldment. Initially I thought the center would be all the controls logic, but then again I've never seen a 'small' automotive motor controller. The blob is clearly labeled with a vishay part number and it appears to be just the DC bus capacitor. Following the 48v connector feed into the power distribution board we hit this, non-descript blob. It has bus-bars going thru it, it could be a fuse but that would be hyper-annoying. I'm going to guess it is a latching relay. It is heavily potted in place.
So here is a zoomed in phase drive

This is a really interesting design, the mosfets are directly bonded to the heat-spreader PCB, the motor phase connections are ultrasonically bonded to the PCB busbars and the PCB busbars are ultrasonically bonded to the PCB. For clarity I've labeled the capacitor bus bars that are also ultrasonically bonded to the board. This is wild. Gate drive is wire-bonded to the PCB and silicone gooped to prevent vibration from wiggling them out. There are four separate wire-bonded half-bridges arranged in parallel. The die-size looks like ~ TO-247 sized, its slightly larger than what normally is in a TO-220. The capacitor in the center is incredibly custom. Outlined in blue and green are the gate drives for each of the half bridges.
Speaking of the capacitor

The bus capacitor is a really curious Vishay part. 470uF, 63V.
It kind of follows this part series [link] [local copy]. If this is actually in the same family, we learn that this capacitor is an automotive qualified film cap, rated for up to 150C. This makes sense as that cap is in a fairly miserable environment. Its 'cooled' by the engine coolant loop [~100C], its connected to a vibrating engine, and the ripple current has to be fairly high. The whole center of the motor controller power stage is just giant bus capacitor with a fairly excellent bus-bar interconnect.
Lets get back to that mystery 'relay'

So the 'relay' overmold part number didnt come up with anything useful,

I began tearing down further and found that there was another part number underneath the overmold. 'VAC' is a somewhat annoying name, as when you look up 'VAC relay' you get volts ac not VAC. Fortunately I found a logo: VAC is vacuumschmelze. Wow that's a name, browsing their website we don't really see automotive relays, but we do see current sensors [link] and common mode chokes. I'm now thinking this is a big ol' DC current sensor, it could be an automotive version of this [link]. At least it appears to not be a 'relay' that needs to be enabled.

Ghost Hunting, the case of the hidden bus-bars

So with some aggressive chiseling i was able to get to the bus-bar path, its looking more and more like that the mystery VAC part is indeed a DC link current sensor. I'm somewhat surprised the hybrid motor return current is routed through the frame. At 9kw (48v) that's +150A, something is a bit fishy. I guess conventional starter motors are +100A and route power through the frame, so it may not be terrible. Note the orange tape is in shot to prevent debris from getting caught in the conformal coat goo that coats the transistors.
Lets see who's driving this bus

After a comical amount of prying, and grinding away at the welded in copper bus-bars here is what is hiding underneath. The coolant loop on this is ridiculous, it loops up around the back of the case to exchange heat out from the three phase inverter, two oval o-rings transfer from the stator coolant to the rear plate. The control logic is actually hidden under a thermally adhered plastic lid. This was also miserable to remove. The control PCB connects to the motor controller through custom pass-throughs milled out of the aluminum case. There is a ridiculous amount of control PCB here to take a look at.
A look at the big board
Here's a direct facing view of the big board. We have a few interesting observations here aside from 'woah this is a lot of stuff to run a motor'. We see THREE can transceivers. Each phase has two FAN7171 4A gate drivers [link], the rotor position is detected with an ADA4571 magnetic hall effect sensor [link], even more curiously its one of those analog sin-cos analog output ones. Finally there is a giant frigging 32bit blob [link] doing all the heavy lifting. That micro is 60$ in quantity 1. This is a monster.
Some interesting design notes: Phase Current Sense
One thing I noticed that was curious was how is phase current measured? Given that this is an induction machine, phase current is not as terribly important as in a BLDC device. There's a real weird smt device carved into the board, hiding next to each phase. This has to be some kind of hall effect driven current sensor, its positioning is so incredibly weird to be anything else.

Digging into diagrams
Thanks to jlwranglerforums we have some basic diagrams, of questionable copyright [link].
To make things less questionable here's my rendition of what goes into this motor. ITS A MOTOR HOW DOES IT HAVE 3 CAN BUSES.

Given that there is a bit of diagramming, i'm going to try and condense things in a somewhat simplified visio diagram.


I made a simplified, readable diagram for what connects to the E-Torque motor. Nominally its not terrible, There's two legs of the CAN-C bus, one LIN bus and then the two very unknown CRANK POSITION sensor inputs. One interesting thing may be seeing what happens when +48v is applied and +12v is applied to pin 12 and then an 'engine start' is applied on pin 6. Its possible it 'just spins for a bit' but I have no idea. Its also not clear why the CAN-C bus loops through the motor. A link to the diagram is available here [pdf]. There are a lot of other things on the CAN-C bus and the LIN  bus, but this should be the rough beginning.

Here is a copy of the LIN specification [link].

An interesting technical video on the etorque system for technicians. A local copy is available here [link] in case this is pulled from YT.


(There's other photos in the photo gallery)
Concluding Remarks:

If you have questions or comments, ask below or send over an email.
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Stay safe when working with electrons in aqueous / semi-aqueous environments. Also wear sunscreen, I'm not responsible for your newly acquired winter-farmers tan : ]

Rensselaer Polytechnic Institute 
Electrical & Electrical Power