How is the rpm of MG1 and MG2 measured?

Discussion in 'Gen 2 Prius Technical Discussion' started by T1 Terry, Feb 23, 2020.

  1. T1 Terry

    T1 Terry Active Member

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    I'm looking at the possibility of using the Gen 2 transaxle and an electric motor to replace the ICE motor. I understand that MG1 spins in the reverse direction to MG2 and if I lock the planetary set then MG1 and the ICE output shaft would spin backwards. To get any useful output from MG1 with a locked planetary set it would require MG1 to be spun backwards and I believe this does occur sometimes in normal operation. This would require a modification or completely different VFD (inverter) to drive MG1 and MG2 and a 3rd VFD to drive the added electric motor that would replace the ICE.
    Hopefully I haven't lost everyone yet :lol:
    If I can measure the RPM of MG1 and drive the additional electric motor at an rpm that would stop MG1 from over speed, could the original equipment VFD (inverter) still be used to drive MG1 & MG2 yet not be road speed restricted because of the over speed of MG1?

    The question put another way, is the road speed limited because the computer sees an over speed of MG1, or is the computer monitoring road speed to determine the rpm speed of MG1?

    T1 Terry
     
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  2. Elektroingenieur

    Elektroingenieur Senior Member

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    Without addressing the the feasibility of your proposed modification in general, I’d note that MG1 and MG2 have dedicated resolvers that allow the hybrid vehicle control ECU to detect the absolute position of the rotors, from which it can compute rpm. See the THS-II chapter of New Car Features (more info) for the 2004 Prius; that chapter also has several nomographic charts that may be of interest.
     
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  3. T1 Terry

    T1 Terry Active Member

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    Thanks for that info, do you know if all the Gen 2 Prius models would have the same set up as the 2004 model or should I look for the New Car Features for the particular model transaxle I find at the wreckers (dismantlers) that I'm going to explore? Is there some where the "New Car Features" can be downloaded?

    T1 Terry
     
  4. ChapmanF

    ChapmanF Senior Member

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    The New Car Features Manual for the first year of a generation (2004, in this case) contains the bulk of the technical information; the same manual for later years in the same generation will describe only minor year-to-year differences. They won't have changed how the resolvers work.

    The blue (more info) link that Elektroingenieur kindly supplied will indicate ways you can get access to the manual.
     
  5. T1 Terry

    T1 Terry Active Member

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    Thank you. Just needed to look with both eyes open it seems but I found the link to Toyota Australia. Unfortunately it doesn't list anything like a New Car Features Manual, just warranty manual and a workshop manual.

    T1 Terry
     
  6. ChapmanF

    ChapmanF Senior Member

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    I don't know anything about how the .au site is organized. Maybe Elektroingenieur will have more information. Warranty manual sounds like the stuff you see on the outside of the paywall, but I'm not sure what "workshop manual" you're seeing. In the US, those are on the inside of the paywall, which is also where the NCF is.
     
  7. Elektroingenieur

    Elektroingenieur Senior Member

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    On the toyotamanuals.com.au home page, if you enter “Prius” in the search box and set the Document Type to Service & Repair Manual, one of the documents is “Prius 20 Series Service & Repair Manual (Aug 03 - Apr 09),” which I expect would include at least the Repair Manual, New Car Features, and Electrical Wiring Diagram.

    The FAQ page for that site does discuss New Car Features, and it’s also mentioned in Toyota Australia’s submissions to the Australian Competition & Consumer Commission in November 2017 (PDF) and November 2016 (PDF) as among the available information.
     
  8. ChapmanF

    ChapmanF Senior Member

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    Browsers have become fairly strict now about showing content (in particular JavaScript) from unverifiable sources. Of the links above, the first one starts with https and will display in my browser, but the second and third are missing the https and show up completely blank in my browser (nothing but the little crossed-out padlock in the location bar to even suggest what's wrong). If I change them to have https in front, then they show up.
     
  9. T1 Terry

    T1 Terry Active Member

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    Thank you all for all your patience and help. I've found a few other links with lots of very useful information from people who have messed with the Prius transaxle as well so I think I might be ready to tackle a transaxle and inverter from the Wreckers (dismantlers) and try my ideas out to see if they will work or not.
    I'd love to be able to still use the Toyota inverter and computer in the PHEV ICE Kill mode and drive the ICE input shaft at 1,000rpm with another electric motor when above 65km/h (40 mph) to slow the MG1 rpm rate enough to reach 110km/h (72 mph)

    T1 Terry
     
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