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  #1  
Old 08-28-2012, 07:30 AM
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jddcircuit jddcircuit is offline
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Default 1991 MR2 + 2004 Prius Transaxle

I got a new donor car yesterday and I wanted to post to mark the beginning of this conversion. It is a 1991 Toyota MR2. I have a 2004 electric transaxle and inverter out of a Toyota Prius that I am going to put in it. I have been experimenting with the control of the electric transaxle for some time now with partial success. I was trying to fit it into a 1966 VW squareback but I got overwhelmed with the amount of rust and restoration that was needed on the donor body. I should have listened to the advice of others that cautioned about what makes a good donor car. I have to learn the hard way apparently. I may still be in the hard lesson mode since there are not many people trying to use the Prius motors but time will tell.

This car needs nothing but a paint job and the interior is perfect so I can focus solely on the electro mechanical aspects of the project. The mid engine design looks like it will work well for my transaxle and conversion plans.
mr2_a.jpgmr2_b.jpg
I will post some pictures of the engine removal once that happens but the wife has declared that there will be no dis-assembly until the VW shell is gone.

The first phase of my plan is to get the car to a grocery getter stage with the small 48 cell 40Ah pack that I already have. In this stage I am not going to bypass the DC boost within the inverter and I am only going to engage the main traction motor (MG2). In this configuration I will be limited by the boost circuit of a 100 battery amps or so.

Once this is functioning I will attempt to increase the power. This is where the fun will start. In addition to adding more cells I have a couple of ideas how to get a considerable amount of power with the Prius setup. I can either start to include the other motor/generator (MG1) and bypass the boost circuit or I can use the MG1 inverter stage IGBTs and some additional inductors to increase the DC boost circuit capacity driving MG2.

Thanks
Jeff
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  #2  
Old 08-28-2012, 11:35 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

Sounds like a very interesting and very in depth project Jeff. Can't wait to hear more.
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  #3  
Old 08-29-2012, 07:21 PM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

its nice to see someone attempting to reuse a prius synergy inverter.

im waiting for the inverters to go down in price on ebay, before i grab one to tinker with. theere's many of them for sale, but the idiot sellers dont realise that no one changes a faulty inverter, since its bullet proof, and most times, covered by waranty. very soon, ebay will be flooded with this inverters from wrecked priuses,

i dont mean to bust your bubble but that inverter is not "intelligent". cannot operate by its own, it still needs the main ecu to control the boost converter, mg1, and mg2.

this guy tore one down: http://techno-fandom.org/~hobbit/cars/ginv/

from your post, seems that you have already figured that out. looking forward to your conversion, and success.
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Old 08-30-2012, 09:48 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

Quote:
Originally Posted by DDDvvv View Post
its nice to see someone attempting to reuse a prius synergy inverter.

im waiting for the inverters to go down in price on ebay, before i grab one to tinker with. theere's many of them for sale, but the idiot sellers dont realise that no one changes a faulty inverter, since its bullet proof, and most times, covered by waranty. very soon, ebay will be flooded with this inverters from wrecked priuses,

i dont mean to bust your bubble but that inverter is not "intelligent". cannot operate by its own, it still needs the main ecu to control the boost converter, mg1, and mg2.

this guy tore one down: http://techno-fandom.org/~hobbit/cars/ginv/

from your post, seems that you have already figured that out. looking forward to your conversion, and success.
Thanks for the encouragement.

I am making my own ECU. I have a couple of versions that are a ways from optimal but do sort of work. I got screwed up with my first donor car which was holding me back quite a bit. I hope I am able to mount the transaxle in this car in relatively short order and get on with the inverter/motor control aspects of the project.

I bought the Prius inverter, transaxle, and half shafts off ebay for $550.

I consider this a low budget conversion project.

Jeff
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  #5  
Old 09-10-2012, 07:32 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

I got the ICE out this weekend.
OutWithOld.jpg
Degreased the engine bay.
EmptyEngineBay.jpg
And starting to line up the new motor mounting.
InWithNew.jpg

I looks like the MR2 axles might work with only light modifications. The inboard CV joint shaft has the same spline as the prius so should plug right into the differential, but the outer diameter of the CV cup hits the transmission housing. I hope with a little grinding I can make it work. "Better to be lucky than smart".

I have decided to use the 2001 transaxle with MG1 and MG2 welded together in instead of my 2004 transaxle for this first trial. My idea is that this motor will spin at a higher rpm with lower battery voltage without using a battery boost converter. I may have less torque but hopefully good enough and a better match for my smaller battery pack for now.

Now I am working on my motor mounting options. I might build a frame to fill the void left from the ICE to connect to the far motor mount and fill it with batteries to help balance out the weight side to side.

My body is not used to this kind of manual labor. Hopefully I can get past this part of the job without too much injury.

Regards
Jeff
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  #6  
Old 09-10-2012, 07:49 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

I forgot to mention that I also removed the gas tank from underneath the car.

I have no experience with AirCon compressor and refrigerant. You can the see the compressor dangling in the engine bay picture. I would like to purge the refrigerant and remove it for reattachment to the transmission ICE shaft later in the project.

If anyone has experience or suggestions with this to help me avoid any pitfalls I would appreciate it.

Jeff
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  #7  
Old 09-16-2012, 11:01 PM
fireblade fireblade is offline
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Default Re: 1991 MR2 + 2004 Prius Transaxle

Check my posts. There are references to CANBUS control of the inverter/converter.
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  #8  
Old 09-17-2012, 06:47 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

Quote:
Originally Posted by fireblade View Post
Check my posts. There are references to CANBUS control of the inverter/converter.
Will do
Thank you
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  #9  
Old 09-20-2012, 08:38 AM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

I bought myself a transmission jack and lifted the Prius electric tranny in place. Fits like a glove.
Gen1TrannyFit (800x598).jpg
I had a clearance problem at first but noticed that the MR2 inbound CV cups on the two axles were non-symmetrical. Swapping the left and right gave about an inch extra position shift in my favor.

I also thought that I had to grind down the MR2 CV cup for clearance but this was not case so the only modification was swapping the left and right cups.

I am now going to start framing up the mounting. My rough plan is to build a battery support structure where the ICE used to be.

Long term goal is a preassemble transmission + inverter+ battery unit that can be swapped out for the MR2 form factor in a single day with minimal donor modifications. This is my plan even though I don't expect my prototype to resemble this goal at first attempt.

Jeff
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  #10  
Old 09-22-2012, 03:58 PM
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Default Re: 1991 MR2 + 2004 Prius Transaxle

Fantastic idea this, if successful you'll have a serious winner! Love the donor choice also! Perhaps would have gone for a later MRs (3rd edition) as it's lighter etc, but then also smaller and more cramped so hard to choose. I follow with great anticipation!
Tyler
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