Prius Gen3 Inverter Hacking

[Bigpie]

I had intended it to be only for model numbers that are confirmed to fit with the board on evbmw, I put on the number Damien has, maybe it's too early to put others on there, or a column needs added for confirmation of fitment

[Mouse]

To make it less confusing I've added a column to mark compatibility.
I've left it blank as I'm in no position to say Yay or Nay to any of them.

[Aquinax]

So am I off designing a Yaris/Auris board then ?:)

if you are going to say that this hardware is incompatible with your board, then yes: D

assy


logic


inverter


AQUA

[MattsAwesomeStuff]

Bit of a tangent... a guy on the DIYEC forums was asking about the whole Gen2 transaxle thing and I couldn't find him a clear answer.

I'm not sure what the difference was between what Damian did to the Lexus gearbox (with external oil pump) and the Prius gearbox, if any.

The user has an operational Gen2 Prius, and notes something I haven't seen discussed before: "With the ICS Kill applied (basically the fuel pump disabled) it can reach 85km/h (roughly 50mph) when the battery is fully charged. I understand this limit is to avoid over speeding the planetary set."

So here's the diagram of the drivetrain for anyone curious:



And, naturally, if you lock the Engine output (planetary carrier), with the ratio difference between MG1 and MG2, you're going to be spinning MG1 what looks (if scale in the diagram) maybe 4x as fast as MG2. Can MG1 handle that at highway or above highway speeds? Is it a concern? Is it not a concern?

The user also asked about using a Gen3 inverter to run the Gen2 transaxle (since the Gen3 inverter control board is more mature), and I suggested that's probably no issue, as the motor has basically 6 power inputs and is otherwise agnostic of how the 3 phases are powered. But, as always, I'm not sure.

[jnsaff]

The answer will be in this video: IIRC the Gen3 was the first one that had the Motor Speed Reduction setup and is suitable for EV only mode.

[celeron55]

I wonder if it would be possible to weld the sun gear to the ring gear instead of locking up the planet gear carrier. That would bring down mg1 speed, right?

Or maybe you simply can drive it 50% faster than intended and it simply won't explode. That sure would sound like Toyota to me.

Gen2 is cheap. It doesn't make sense to give up on it so easily.

[MattsAwesomeStuff]

The answer will be in this video: IIRC the Gen3 was the first one that had the Motor Speed Reduction setup and is suitable for EV only mode.

I watched the whole video. I can't quite understand what's going on and what the problem would be if you forced MG1 to spin the same speed as MG2.

I do recall at one point he said there was a 2.61x reduction, which I think was referring to the planetary gearset, but I'm not sure. Also, MG2 on Gen2 is capable of spinning a lot faster than it was on the Gen1. 10,000RPM vs. 6500 RPM. 10,000 RPM for MG2 is 103mph.

So if anyone finds out the MG1:MG2 gear ratio, you can apply that to 103mph that MG2 is rated for.

It's a long video, here is where he starts putting it all back together, maybe someone else can make more sense of it than I. I get close but I can't picture it all in y head at once:

[sfk]

I wonder if it would be possible to weld the sun gear to the ring gear instead of locking up the planet gear carrier. That would bring down mg1 speed, right?

Or maybe you simply can drive it 50% faster than intended and it simply won't explode. That sure would sound like Toyota to me.

Yes you could weld up the planetary gearset can effectively create a solid coupling between MG1 and MG2. They will then spin at the same speed. Obviously this will involve taking the gearbox apart and some irreversible welding to achieve. If you need to replace the gearbox for some reason in the future you'll need to redo all this same work.

Locking up the ICE input shaft is a lot more simple and can be done without taking the gearbox apart. But MG1 will always be spinning faster than MG2 and therefore potentially limit maximum speed due to max RPM of MG1.

But a more elegant solution would be an engineered solid coupling that takes the place of the planetary gearset (PSD - power split device in Toyota language). Be aware that Toyota used several configurations for various Prius gearboxes. Some have the motors co-axial and some are offset and connected by drivechains.

[GaryClarke]

And, naturally, if you lock the Engine output (planetary carrier), with the ratio difference between MG1 and MG2, you're going to be spinning MG1 what looks (if scale in the diagram) maybe 4x as fast as MG2. Can MG1 handle that at highway or above highway speeds? Is it a concern? Is it not a concern?

I don't think over-spinning is ever a problem for our intended use.

I've been watching this clip on loop, trying get my head around it.



In our use, the PSD is welded so the effective gearing is 1 to 1. MG1 never over spins because MG2 can never make it do so.

Only in hybrid use could MG1 over spin. The gearing of the PSD means that MG1 would spin 2.61 times faster than MG1 - in the opposite direction.

In this condition only, can MG1 theoretically over spin. But it doesn't because a current drives MG1. The effect is to slow down MG1 relative to MG2. But at the same time, the gearing of the PSD means that the ICE drive shaft spins. The ICE fires up and starts to spin the drive shaft. This applies a mechanical force through the PSD. MG1 slows further, ultimately changes direction; speeds up, overtakes the speed of MG2. Once it's spinning faster than MG2 it becomes a generator for the battery pack from which MG2 draws current to then accelerate up to it's maximum speed.

In our use, if we powered MG2 alone could then MG1 potentially over spin. But by welding the planet gears, we lock the sun gear on the drive shaft (MG1) to the ring gear (MG2) effectively creating a single shaft and single motor with two windings.

This now leads me to question why we don't power both motors electrically. Is it just less efficient because the ICE drive shaft would be spinning wasting energy?

Edit -iAlso, just locking the driveshaft still allows the PSD to operate. MG1 and MG2 can still turn independently. Is it this configuration that could result in overspinning?

[MattsAwesomeStuff]

[Edited to add: This is without the context of the post above mine... which makes me less certain again. Maybe ignore most of this except the technical errata]

So, watching another hour of video...

Gen3 has an extra set of planetary gears in the transaxle, at MG2. The purpose of which, in his conclusion, is to reduce the EV-only speed of MG1 to a safer number, (basically matched to MG2, 1.014:1 ratio).

Gen3 Transaxle. Timestamped appropriately, first few minutes tell you:



In Gen1, MG1 max speed: 6500 rpm
In Gen2, MG1 max speed; 10,000 rpm
In Gen3, MG1 max speed: 13,500 rpm (and easier to EV-only, with the second planetary to keep MG1 slower).
In Gen4, MG1 max speed: 17,000 rpm.

Also, confirmed, 2.61x ratio of MG1 to MG2.

He also notes that you can get up to 61mph in EV-only mode on the Gen3 before the motor would turn on, which he suggests has something to do with the max rotational speed of the motors.

... In conclusion-ish... I think welding or locking the Gen2 transaxle is almost certain to overspeed MG1. At least according to spec. But that this would not be a problem on the Gen3s.

I'm not great at interpreting these things, so, no one go make any big decisions without verifying it yourselves.

[MattsAwesomeStuff]

Only in hybrid use could MG1 over spin. The gearing of the PSD means that MG1 would spin 2.61 times faster than MG1 - in the opposite direction.

[...]

In our use, if we powered MG2 alone could then MG1 potentially over spin. But by welding the planet gears, we lock the sun gear on the drive shaft (MG1) to the ring gear (MG2) effectively creating a single shaft and single motor with two windings.

[...]

Also, just locking the driveshaft still allows the PSD to operate. MG1 and MG2 can still turn independently. Is it this configuration that could result in overspinning?

Is there a mechanical difference between locking the driveshaft like Damian did with the cut down clutch plate gear, versus welding the planet gears? I'm sure I could figure that out but when I bumble things around in my head too much my brain will say yes to everything.

This now leads me to question why we don't power both motors electrically. Is it just less efficient because the ICE drive shaft would be spinning wasting energy?

Who's "we"?

Toyota we, or like, DIY repurposing here on these forums "we"?

Short answer, we do. At least if we want to. That's what Damian did in a drive test some time in the last month or two (maybe that was the lexus, but, same deal). I recall him saying it was a lot more power with MG1 + MG2 rather than just MG2.

[sfk]

Is there a mechanical difference between locking the driveshaft like Damian did with the cut down clutch plate gear, versus welding the planet gears? I'm sure I could figure that out but when I bumble things around in my head too much my brain will say yes to everything.

Yes, there is a mechanical difference. Locking the ICE input shaft would result in MG1 spinning about 2x faster than MG2 due to existing gearing of the planetary gearset.

Welding the planetary gearset would effectively create 1 driveshaft with 2 motors on it. Both spinning at same speed as it's now 1 driveshaft.

[GaryClarke]

Either welding the PSD or locking the driveshaft achieves the primary aim of combining the output of both motors, but there is a secondary issue that determines which method can be used.

Starting the video below at a point to highlight the important difference in design between Prius FWD transaxles and the Lexus RWD.

The oil pump. Internal on FWD but external on RWD. Internal is driven by driveshaft.

Therefore on Prius FWD boxes the drive shaft must be able to rotate or else oil will not circulate. This is not an issue on RWD because oil is circulated by an external oil pump.

So on Prius FWD boxes we must disassemble and weld the PSD ( or design an external oil pump). On RWD we can opt for locking the drive shaft

[Snufkin]

Here is an interesting simulation showing Power Split Device - speed relations. But I am not sure which generation it shows.
http://eahart.com/prius/psd/

[NiHaoMike]

As a compromise, what about fit a one way clutch on the engine shaft so that MG1 can spin the wheels, but the wheels/MG2 cannot spin MG1?

[Jack Bauer]

Folks, this thread is about hacking the Gen3 inverter. Please start a new thread for discussing modifications to the transaxles.

[NiHaoMike]

I was tracing out the logic board for a Gen3 inverter and I found out that the 5V on pins 7, 8 and the 5V supply on pins 15, 17 are derived from separate regulators. My guess, based on their locations, is that 15, 17 is for the power board logic and 7, 8 (along with -5V on pins 3, 4) is for the power board analog circuits. I'm pretty sure that's done for a good reason, although the -5V (which is also for the analog circuits) is supplied directly from a switching supply with no obvious filtering.

I also find it unusual that there does not appear to be anything to give a boost inductor current signal back to the control circuit, even though it's obvious the power board must be doing current sensing to protect against overcurrent faults. Could that be the function of one of the "unknown" pins? I'm going to guess the motor outputs have actual sensors since the current sensing inside the power transistors is not accurate enough for motor control, but the boost current is a lot less critical so using the transistor internal sensing is enough.

[jnsaff]

Just another data point for Auris inverters. Inverter model: G9200-47190 control board: F1759-47070 05. If I understand it correctly it's 2017 RHD.

Underneath I have an unpopulated Gen3 board from Damien as a comparison. The control board measures 143x154mm connector has 50 pins.

I shall now go and hunt for an actual prius inverter so I can get spinnage sooner!

[Jack Bauer]

Would this be the time to tell you all that I've actually just finished the Auris / Yaris variant.....

[jnsaff]

This would be the time indeed! Take my money!

[jnsaff]

Hey JB, do you have any updates on the Auris board? I'd be willing to be a guinea pig and can order from JLC myself too would just need the design files. TA!

[kalebludlow]

can order from JLC myself too would just need the design files. TA!

I'm in this group, Prius C inverter in the mail ready to be Damienified

[Jack Bauer]

Yeah the plan is I need to make some mods to both boards on the boost controller mcu as per discussion with celeron55. Once done I'll have them for sale and up on github. I'm in the process of installing a gen 3 inverter in my E39 along with a a Siemens 1pv5135 motor. This will act as a good test bed so please bare with me. Ive handed over the Tesla drive unit boards to Johannes to give me more bandwidth to concentrate on the Toyota side of things.

[Jack Bauer]

Please see attached schematic for new rev of prius gen 3 logic board.

Changes :

1- Boost converter based charger atmega328 pinout now as requested by celeron55. Includes evse control and can bus connections.

2- added optional resistors to allow parallel drive of MG1 and MG2 power stages for experiments with dual motor and / or increased current output.

3 -Changed resolver exciter to TDA2822 (ripped of Johannes design yet again)

4 - added resistors to allow setting of dcdc converter 12v output voltage

5 - i/o pins via 34 way idc header. A separate board to be mounted on the case connects via a short ribbon cable to an Ampseal 35 way header.

So hopefully this puts us a step nearer an integrated inverter / charger / dcdc converter module. I will leave this schematic out there for a week to allow for comments before starting pcb layout and prototype order. The same design will then be applied to the Yaris / Auris board design.

[Bigpie]

I've scored an inverted from ebay for £90 but it doesn't come with the ampseal connector. Any one got any leads on a supplier?