There are a few different variants of the Model 3 RDU in the field. Looking at some measurements, I think I'm going to want one the 3D6 variant, which has the newer "hairpin" style stator windings, and the performance specs (lower "optimal" voltage of 320v instead of 335v). The 3D7 might even be better (wider range of speeds where it has power), but it would require a different battery architecture (higher voltage) which would throw off my plans for the AC/DC and other things...
Looking into driving the Tesla Model 3 RDU itself, there are a few different ways to interface with it:
- Ingineerix on youtube posted a video in 2020 showing the interfacing via CAN: https://www.youtube.com/watch?v=LWVt5I0XKyk
- EV-Controls sells a commercial solution to do the same https://www.ev-controls.com/product/ev-controls-t2c/
- There's a massive thread on openinverter about the model 3 drive unit which has been going on (also since 2020): https://openinverter.org/forum/viewtopic.php?f=10&t=575
I'd prefer greatly to integrate the messaging/control to the motor into whatever CAN/CAN device I have to develop to drive the existing onboard electronics and interface with the charger and BMS... but unfortunately life doesn't appear to be that simple:
The Tesla drive units have quite a bit of logic on them, amongst the responsibilities of the inverter is implementing a cryptographic challenge to the security controller (part of the immobilization system). No (paired!) security controller, no dice. I asked Ingineerix via reddit messages if he had any hints or suggestions, and he very kindly responsed with these salient points:
- The information to bypass the security pairing is extremely sensitive as it'd allow people to trivially steal cars. I'd have to reverse-engineer it myself, which considering it took Ingineerix months with access to a working car and years of experience working with automotive CAN (and electric conversions) puts this into the realm of "not really possible"
- Once the motor is outside of the car, the pairing process between motor and security controller is extremely difficult if not impossible, and you'd need access to Tesla's service tools to do it
- Be sure to get the connectors that go to the motor, as you can't get them aftermarket (and most sellers don't include them)
- It's a really bad idea to do this piecemeal, and much smarter to buy a whole (dead) model 3 donor
If only I had the space... looks like I will be budgeting for the T2C. I also sent Ingineerix some "gas money" as his advice has definitely saved me some pain, time, and money.
