Is the CVT Function of Prius Transaxle working with OI Board?

[DonKarlos]

Hi,
most likely I overlooked something and I need again a little jump start...
As I understood the original setup of a Prius Hybrid has a CVT Transmission with two Motor/Generators. One is a bigger one (MG2) and one is a little bit smaller (MG1).
MG2 has the sole? function to propel the car in electric mode. MG1 has some more functions. First is to start the ICE. Second is to deliver charging current in Hybrid mode and maybe in recuperation. And the third is to manipulate via the planetary gear set the CVT "gear ratio" of the transmission. My question is now, since I have in my current setup in my Audi A2 a manual gearbox with fixed gear ratios, if my car could benefit from the CVT Funcionallity of the Prius transaxle. Therfor it would be necessary to control MG1. Is that possible, or is the Prius transaxle in an open inverter setup a direct drive fixed gear ratio setup? If it is a fixed gear ratio setup, how fast could it go from 0 to max RPM of MG2 with 15" Wheels?
My Audi A2 goes 0-50 in 1st gear remarcably quick. In 3rd gear I can drive comfortably from 0-100. But the current goes up when reaching the top speed. Than shifting to 4th or 5th gear reaches max speed with my synchronous 40 Kw Motor at 130 Km/h with acceptable currents and no overheating of my battery (I have a heated Zebra-Battery).
If this question has been answered 1000plus times I am sorry for not finding an answer which is understandable for me!!! And it is not a Question like: Why is it so limited....because it can do already so much, that it is, without all the input from you, way above my abilities So please be kind:-)
Many Thanks in advance!

[Jacobsmess]

In a nutshell no, but I think the reason is that you need a 3rd motor and another inverter to drive the engine input shaft in order to modulate the output speed using MG1. It's something I'm going to experiment with shortly but as I understand it should be possible, the difficulty is the control of the 3rd motor speed and a second inverter. I'm hoping that a simple solution should be possible using the zombieverter but I've not got my hands on one yet.

[DonKarlos]

Thanks for your input! As I understand the system, it is working as a CVT transmission in pure electric mode as well!? If the ICE is off, the car could still drive in electric mode and than the transmission would continously vary the gear ratio by controlled turning of MG1 (cw and ccw probably). This would mean, that you would have to control only the two MGs and holding the ICE input shaft. Are my thoughts wrong? To be honest, I never drove a Prius hybrid;-)!

[Jacobsmess]

Thanks for your input! As I understand the system, it is working as a CVT transmission in pure electric mode as well!? If the ICE is off, the car could still drive in electric mode and than the transmission would continously vary the gear ratio by controlled turning of MG1 (cw and ccw probably). This would mean, that you would have to control only the two MGs and holding the ICE input shaft. Are my thoughts wrong? To be honest, I never drove a Prius hybrid;-)!

Neither me and my understanding comes from the Lexus drivetrains but as I understand, by locking the input shaft you then fix the ratio, whereas if you were to be running the input shaft, mg1 rotates the PSD faster than it would turn normally by the ICE on its own.

[johu]

I only know about the Gen2 Prius transmission and I think the Gen3 is similar. With the input shaft locked (==engine off) MG1 has twice the gearing of MG2. This ratio is not variable. MG1 can be used to deliver some extra power with the only downside that it exceeds its rpm rating at higher speeds. To overcome that the planet gear responsible for the 2:1 ratio between MG1 and MG2 can be welded then they both run at the same speed.

[MattsAwesomeStuff]

I only know about the Gen2 Prius transmission and I think the Gen3 is similar.

It's similar, but different, possibly opposite. I.E. dangerous to equate.

I keep forgetting what the difference is. IIRC you weld different things on them if you want to use MG2.

Would be nice if someone wrote this all down.

[johu]

Someone watch and write

[DonKarlos]

Ok,
having never driven a Prius before I can't confirm, that the CVT is working or not in pure electric mode. Johannes converted a Audi A2 with a Prius Transaxle and it drives around 100 Km/h in his driving video. In this case CVT is not working I assume. I found in the PRIUSCHAT forum further Information in the "MG1/MG2 RPM's (Scangauge)" Thread, which was started by User Canard. User Judgeless posted a link to this article from http://eahart.com/prius/psd/ with a little calculator for the rpms of MG1/2 and ICE. Interesting Info. Maybe there is a way to use the Dual motor board with blocked ICE Input shaft to use the CVT....? But it also shows, that the MG1 is the limiting factor with ICE at 0 RPMs (at least I understand the logic that way...) I don't know as well, which Version of Prius Drivetrain is simulated.

[Jacobsmess]

Ok,
having never driven a Prius before I can't confirm, that the CVT is working or not in pure electric mode. Johannes converted a Audi A2 with a Prius Transaxle and it drives around 100 Km/h in his driving video. In this case CVT is not working I assume. I found in the PRIUSCHAT forum further Information in the "MG1/MG2 RPM's (Scangauge)" Thread, which was started by User Canard. User Judgeless posted a link to this article from http://eahart.com/prius/psd/ with a little calculator for the rpms of MG1/2 and ICE. Interesting Info. Maybe there is a way to use the Dual motor board with blocked ICE Input shaft to use the CVT....? But it also shows, that the MG1 is the limiting factor with ICE at 0 RPMs (at least I understand the logic that way...) I don't know as well, which Version of Prius Drivetrain is simulated.

As I've understood it, MG1 being the limiting factor makes sense as it is this that modulates the ratio to ICE output speed. When the ICE is not rotating the max speed is dictated by mg1 speed alone. BUT if you turn MG1 against ICE you get overdrive.

At least this is the case on all the Weber deep dive videos I've seen.