Prius Gen3 Inverter - Maximum Achievable Power

Topics concerning the Toyota and Lexus inverter drop in boards
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Pete9008
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Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

Does anyone have experience of getting more than around 50kW though a Gen3 Prius inverter (or Gen2 for that matter)?

I'm planning on using one for my conversion but would like to be able to get 100kW though it (350V and 300A DC). Based on the maximum current figure of 500A this would appear to be possible. The concern is that I can't find anyone who has achieved this, Bigpie's install seems to top out at 35kW and the most I can see in Damien's videos is around 50kW both of which are quite a bit short of my goal, they do seem to tie in fairly well with Toyota's rating for the inverter though.

I'd like to use this inverter, especially as it's looking likely that the foc issues can be sorted, but I need to be reasonably confident about the peak power levels it can produce.

Right, off to do a bit of research about IGBT ratings and operation.
m.art.y
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by m.art.y »

Pete9008 wrote: Thu Sep 22, 2022 9:27 am Does anyone have experience of getting more than around 50kW though a Gen3 Prius inverter (or Gen2 for that matter)?
Not sure if it will be of any use but in the beginning when I had no idea what I was doing and was trying to get my motor to spin I was messing with various settings and at one point I observed current sensors reporting ~600 A and phase wires were very hot melting the insulation. Not sure what that would translate into DC amps.

Later when I already had the motor spinning I went for a test drive and when flooring was able to accelerate in a way that felt very fast, not Tesla fast but fast enough that it wouldn't make sense driving like that on a daily basis. Motor was rated 50 kW peak and the car was ~800 kg. It didn't cut out, in fact I don't remember having a cut out with the gen3 prius inverter but I perhaps haven't used it long enough.
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Bigpie
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Bigpie »

I've seen 550 phase amps just not been able to put that into a spinning motor, only one with a locked shaft.
Pete9008
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

m.art.y wrote: Thu Sep 22, 2022 10:29 am Not sure if it will be of any use but in the beginning when I had no idea what I was doing and was trying to get my motor to spin I was messing with various settings and at one point I observed current sensors reporting ~600 A and phase wires were very hot melting the insulation. Not sure what that would translate into DC amps.

Later when I already had the motor spinning I went for a test drive and when flooring was able to accelerate in a way that felt very fast, not Tesla fast but fast enough that it wouldn't make sense driving like that on a daily basis. Motor was rated 50 kW peak and the car was ~800 kg. It didn't cut out, in fact I don't remember having a cut out with the gen3 prius inverter but I perhaps haven't used it long enough.
Bigpie wrote: Thu Sep 22, 2022 10:35 am I've seen 550 phase amps just not been able to put that into a spinning motor, only one with a locked shaft.
Thanks for the reply, that's higher currents than I'd seen before which is good.

The trouble is none of that is really power. Current into a locked rotor takes very little power. Acceleration is also fairly subjective, low speed acceleration requires torque (and so current) but needs relatively low levels power, it's only when you get to medium to high speeds that the power starts to matter. M.art.y, can you remember what speeds the above was at?

I've spent the morning reading up on IGBT's and re-reading the Oak Ridge Lab Prius report and I'm still left wondering whether my 100kW target is realistic; I'll try to explain why. The Prius inverter is rated at 60kW but it's also rated at 650V. By almost halving the voltage we run it at should be almost halving the available power so the rated 60kW might drop to say 40kW. Going from 40kW to my goal of 100kW means there must have been a lot of spare capacity built into the inverter to start with - is this realistic to expect? I don't know but my gut feel is it's pushing it. There is the option of combining the MG1 and MG2 outputs, this could give a 50% increase in current if the IGBTs share current evenly. They look like they might be the same devices in pictures and if so they should share fairly well.

Thinking about the currents we see, there are some impressive numbers there which do indicate good power should be possible. Having read up on IGBTs it seems that the limiting factor is normally not the short circuit current or the power dissipation due to DC current, rather it's the switching losses that are normally the limiting factor. Now this is where I get a bit lost, is it possible that there is something different in the relative phase of the voltage and current when a motor is spinning that makes switching losses worse when a motor is spinning compared to when it is locked? If so then that could explain a lot.

Switching losses also increase with temperature so is it possible that the IGBTs are cooler for the static tests so giving lower switching losses and higher currents?

The above has got me wondering whether it is desaturation that is causing trips. Is it possible that the Prius inverter has individual IGBT die temperature monitoring and one of those is tripping out?
m.art.y
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by m.art.y »

Pete9008 wrote: Thu Sep 22, 2022 12:41 pm M.art.y, can you remember what speeds the above was at?
It reached around 50 mph before the stretch of road was over.
Pete9008
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

m.art.y wrote: Thu Sep 22, 2022 12:58 pm It reached around 50 mph before the stretch of road was over.
Thanks, that's encouraging.

Not sure what to do here, my engineering side says that 100kW seems unlikely having reviewed the data (I think 70-80kW with MG1 and MG2 linked is reasonable, more if the voltage is increased) but in terms of packaging and functionality it fits my planned install extremely well so I'm tempted to push ahead and hope for the best.

Have had a look at other Toyota inverters and the Camry is a possibility but tricky to source as it was not sold in the UK. The NX300H inverters seem to be available at a good price and the spec on paper looks good but there seem to be at least two versions and very little information about what's inside them (almost looks like they have 3 motor generator outputs?, do they have the DC:DC and buck/boost converters?).

Edit - Found this on the NX300H which indicates two versions of the inverter, one which supports the front motor and generator and one which supports this plus the rear motor. Also indicates that it still includes the DC:DC and buck/boost modules. https://www.lexus-tech.eu/HYBRID/HVDM/E ... h_AYZ1.pdf

Also think that the RAV4 and NX300H inverters may be very similar.
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Bigpie
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Bigpie »

Jack Bauer wrote: Sun Sep 11, 2022 8:46 am The inverter will not cutout on overtemp but it will limit. The only source for a cutout is the IGBT desat detector outputs.
Damien has also used the Prius inverter with the Siemens 1PV

Edit, with my new PI values I'm able to get to 40kw before cutout
Pete9008
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

Bigpie wrote: Thu Sep 22, 2022 2:50 pm Damien has also used the Prius inverter with the Siemens 1PV
Yep, that's the video I saw 150A at 350V
Pete9008
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

Looks like 100kW is possible with the Prius inverter after all. Ev8 has seen 295A at 312V this accelerating from 30-70mph :D
https://openinverter.org/forum/viewtop ... 961#p45961

And 160kW on a DC install! viewtopic.php?p=45969#p45969

Looks like I'll be sticking with the Prius inverter :)
MattsAwesomeStuff
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by MattsAwesomeStuff »

https://openinverter.org/wiki/Toyota_Prius_Gen3_Board

When I wrote that part of the Prius Gen 3 wiki page, I recorded that MG2 alone was tested and capable of 600v and 500A. It came from one of Damien's videos I'm pretty sure.

I don't think Damien tested MG1, but considering that MG2 is just 50% larger than MG1 (6 mosfets instead of 4), I was figuring around 330 amps on MG1.

That 2/3 ratio held true for what Damien tested on the Prius Gen 2. Just, haven't seen anyone test MG1 on the Gen 3.

350v @ 300amps should be just fine, and well under its limits. Long as you can cool it fast enough anyway.
Pete9008
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by Pete9008 »

MattsAwesomeStuff wrote: Fri Sep 23, 2022 9:45 pm https://openinverter.org/wiki/Toyota_Prius_Gen3_Board

When I wrote that part of the Prius Gen 3 wiki page, I recorded that MG2 alone was tested and capable of 600v and 500A. It came from one of Damien's videos I'm pretty sure.

I don't think Damien tested MG1, but considering that MG2 is just 50% larger than MG1 (6 mosfets instead of 4), I was figuring around 330 amps on MG1.

That 2/3 ratio held true for what Damien tested on the Prius Gen 2. Just, haven't seen anyone test MG1 on the Gen 3.

350v @ 300amps should be just fine, and well under its limits. Long as you can cool it fast enough anyway.
Had a look at the inverter and fairly sure that the ratio on the Gen3 would be 1/2 not 2/3. It has a pair of IGBTs for each switch on MG2 and just the one for MG1. That would give 250A for MG1. I think those are short circuit ratings though and don't allow for switching losses so I'm guessing it would be a bit less than that when running a motor. I'm now planning to parallel MG1 and MG2 on my install and am fairly comfortable that the two combined will be enough.

I've also had a quick look at the IGBT driver circuit. I can't identify the driver IC's but they appear to have a connection to a couple of pins marked A and K on each IGBT die. Fairly sure that this is a temperature sensing diode so each IGBT driver does monitor the individual IGBT temperature. Also noticed that each driver only has two optos to it, one must be for the IGBT gate drive signal, the other reverse one must be the error signal. Now with just one signal I would expect it to perform both the desat and over temperature functions. Based on this I think the error output to the logic board may include both.

Once I have a board up and running I'll try and do a bit of testing to find out for sure.

Still very interested to hear everyone's real world experience with power levels achieved on the Prius inverters.
MattsAwesomeStuff
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Re: Prius Gen3 Inverter - Maximum Achievable Power

Post by MattsAwesomeStuff »

Pete9008 wrote: Sun Sep 25, 2022 7:38 pmStill very interested to hear everyone's real world experience with power levels achieved on the Prius inverters.
To paraphrase Damien when he did it. "Why is it always me who has to test things to failure?"

I too am keen to see real-world performance tests.
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