Tesla Model 3 Rear Drive Unit Hacking

[Jack Bauer]

Early Christmas present should make life a bit easier:)

[Jack Bauer]

All parts placed.

[Jack Bauer]

Ok, Need a bit of advice here. Ol Elon is at it again. The best backup low side psu is ... None? So on my board with the Viper16 based HV psu the low side drivers are spoiled rotten. They can get their power from either the 12v transformer system (big thing in top center of board) OR from a HV derived psu like the Viper16. Diodes D491 and D74 in the pic above prevent back feeding. Great. BUT, the versions of the board that use the NCP1060 HV psu dont do any of this and the Low sides are just powered from the 12v system. Question is, what should I do?

[johu]

Have we ever understood the point of the backup PSU?

[Jack Bauer]

Sadly no. At least not by me. My only thought is this : The transformer has 4 secondaries. Elon dedicates one each to a high side leaving him only one for all the low sides. So is he using the 12v derived psu to just wake the drivers and keep the low sides off until HV comes up and the use the HV derived psu to provide the actual grunt when switching.

wont stop me ordering my fit and placement boards but its a fairly significant design "error" if i get it wrong later

[Jack Bauer]

But that doesnt work on the boards using the NCP1060....unless.........the best anti feedback diode is no diode?

Dammit. I need one of those boards with the 1060. Does anyone have an inverter with this psu and willing to make some measurements? I believe its a "980" type.

[jrbe]

Does the ncp1060 handle the reverse power flow making the diode unnecessary?

Will your 12v source power supply make enough current by itself for all the drivers?

There's oem design redundancy that might never ever be used to what's sensibly required to that didn't work. And unless you do these designs often it can be really hard to know where the idea falls in this range until you test it.

Is it worth breaking out this part of the design to it's own little PC board to test?

Sometimes removing unnecessary / blocking components from a circuit is more of a mindbender than it should be.

No need to reply, just some ideas to maybe help thinking through the logic / struggle.

[Jack Bauer]

Thanks for the ideas.

[Jack Bauer]

This one is even better. Let's just delete all these pesky parts Am I really the only person on the friggin planet looking at this stuff?

[davefiddes]

That's the Font Drive Unit inverter variant is it not? I thought you had one of these. Somebody somewhere said they don't require the extra drive circuitry because it's an induction motor. I am but a humble Mechanical/Software Engineer so don't really understand the implications.

[Jack Bauer]

I "had" one. Sent back to owner prior to house move messed up my plans

[davefiddes]

Ah, forgot the history on that one. I spotted a slightly crispy FDU from a fire damaged car near me...sadly they're looking for silly money otherwise it would be an an ideal dev unit. There don't seem to be a lot of drive units from newer cars about at the moment. Mostly seem to be the older ones like we already have.

[Jack Bauer]

yeah interesting. I'll keep an eye out but wont let it stop progress. I'll setup the board to do the dual psus and can always leave some parts unpopulated.

[Jack Bauer]

Found this on the US 'bay. If you look at the secondary side current regs there is no an option of a 0 ohm resistor to bypass the whole thing and just feed the secondaries from the transformers into the high side drivers.
https://www.ebay.com/itm/395809630591

Also seems the sods have deleted the JTAG connector!

[Jack Bauer]

In fact that reminds me of a Trek line " Shunt the deuterium from the main cryo pump straight to the auxilliary tank"

[davefiddes]

They have had fun. Looks like they've removed the HVIL current sense resistors. Couple of current sense resistor whose purpose I can't remember have gone too (maybe to do with the resolver exciter I think). CAN termination is gone on both busses I think. Who only know what the forest of footprints on the LHS is up to.

[Jack Bauer]

I think the missing bits on the "logic" side are for detonating the also missing pyro on the center bus bar.

[Jack Bauer]

My brain hurts....

[dimonlipko]

Damien, you are crazy!))) Very powerful project! I want to be one of the first tester. My Tesla motor wait in garage)

Remind me why it is impossible to only replace the native chip to STM32 with adapter board?

[Jack Bauer]

I am a bit crazy:) It is indeed possible to fit an STM32 board but the level of skill required to solder it safely in place is very high and so I decided it was not practical for most people. I decided at the begining that whatever solution I developed had to be universal and repeatable and of course open. Here is a video from last year where I tested out a modboard :

[Jack Bauer]

Nearly home....Just B and C phase High side power supplies to track.

[dimonlipko]

Am I correct understand that the software is the same for solution with new board and for OEM board with change MCU?

Is it possible to make more motor power than in Tesla?

Is this board work with model 3 front drive unit?

[Jack Bauer]

Am I correct understand that the software is the same for solution with new board and for OEM board with change MCU?

Is it possible to make more motor power than in Tesla?

Is this board work with model 3 front drive unit?

Yep same stm32-foc openinverter firmware.

Don't know about power until I test. Certainly possible in theory.

Should work in any drive unit that the board will fit.

[Jack Bauer]

She done:) Passes critical drc. Of course it wont work but will look cool and get clicks.

[Jack Bauer]

Board layout and schematic for those playing along at home.