openinverter forum

Lots of wiring and component mounting done in the Bexus.

Is there a chance of you posting a schematic of how the high voltage junction box is wired.

Jack Bauer wrote: ↑Fri Feb 21, 2020 7:44 am Had a hell of a time finding these.

https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1

That's awesome, many thanks. Some more digging and the best Google term seems to be "stand off insulator".

I've currently resorted to cutting out big chunks out of whatever my fuses were originally mounted to - these insulators are a much better solution!

It's funny how similar our projects have turned out - I'm also using a Tesla Gen3 charger in the same location, but I've gutted the end of it that has the supercharger PCB/contactors and am using that as the junction box for my 320V bus. I'm also using the TRW PAS pump, and it looks like the same vacuum pump.

xp677 wrote: ↑Sun Feb 23, 2020 4:12 pm

Jack Bauer wrote: ↑Fri Feb 21, 2020 7:44 am Had a hell of a time finding these.

https://www.amazon.co.uk/gp/product/B07 ... UTF8&psc=1

That's awesome, many thanks. Some more digging and the best Google term seems to be "stand off insulator".

I've currently resorted to cutting out big chunks out of whatever my fuses were originally mounted to - these insulators are a much better solution!

It's funny how similar our projects have turned out - I'm also using a Tesla Gen3 charger in the same location, but I've gutted the end of it that has the supercharger PCB/contactors and am using that as the junction box for my 320V bus. I'm also using the TRW PAS pump, and it looks like the same vacuum pump.

Do you have more info on that (or pics)? That is a very good solution to make everthing appear OEM to evade the EMC testing when converting the car from ICE to EV with the authorities.

I have not published information on that yet. And now I feel that doing so may be a bad idea. I do not wish to publish Information which would be used explicitly to circumvent such testing.

However the procedure is as described. Remove the parts which you do not need and replace with those that you do.

It looks like Damien has kept his charger intact, so this discussion is not relevant in this thread.

xp677 wrote: ↑Tue Feb 25, 2020 11:55 pm I have not published information on that yet. And now I feel that doing so may be a bad idea. I do not wish to publish Information which would be used explicitly to circumvent such testing.

However the procedure is as described. Remove the parts which you do not need and replace with those that you do.

It looks like Damien has kept his charger intact, so this discussion is not relevant in this thread.

Hm, that is indeed a good point. Thanks for the reply anyway

Top balancing the test battery today... here's the rear pack

mattndex@gmail.com wrote: ↑Sun Feb 23, 2020 2:49 pm Is there a chance of you posting a schematic of how the high voltage junction box is wired.

The participants on next weeks course are building a HVJB for the Grey Goose project. It will be very similar to that used on BEXUS. I'll ask them to document the build and post details in that thread

Front of the car all back together. Next up wiring in the V2 VCU with Wifi and ISA Shunt interface.

V2 VCU and isa can shunt up and running in the bexus. VCU now controlling precharge, startup and shutdown as well as hv control during charging. WiFi interface works perfectly.

RE3Rotor wrote: ↑Wed Feb 12, 2020 11:05 pm I did notice mine has 2 drive positions on my gearbox. I would love to know if it is as easy as just connecting the shift lever so I can manually switch to the second location.

It may be possible to wire it up this way. Ive done it for other electronics transmissions in the past.

Weigh in for the GS450H transmission.

Oops, I'm waiting for the gearbox to be delivered, I need a crane to move it ...

Jack Bauer wrote: ↑Thu Mar 05, 2020 6:35 pm

Nice! Definitely great progress.

I heard you say "that's interesting" but couldn't make out what you were referring to. Everything working as expected so far?

-Matt

This is a great project, it has encouraged me to sign up and start planning my own which I will share!

It will be particularly interesting to see how the motor performs on longer test drives.
The main concern I can foresee is how the motor handles heat buildup in a pure EV duty cycle vs hybrid.

Looking at the LS600h analysis done here (which is pretty good btw): https://www.osti.gov/servlets/purl/947393
and comparing it with the leaf motor analysis here: https://www.energy.gov/sites/prod/files ... 2013_o.pdf
It appears that MG2 on its own does warm up quite quickly under load.

The leaf motor test concluded "Capable of operating at 80 kW continuously at 7,000 rpm with stator temperatures levelling out at about 135C".

Whilst the LS600h test results for MG2 found "50 kW operation at 5,000 rpm can be continued for 10:14 and 14:13 with stator temperature limits of 130ºC and 150ºC, respectively." The inverter appears to handle the power fine.

Unfortunately, they didn't test any voltages other than 650V as I am also interested to see what RPM the torque starts to fall off. I am trying to learn about motors but they are a complex beast. I understand that higher voltages are needed to overcome the back EMF as speed increases, but at low speeds will a higher voltage lower the current in the motor windings, or only on the DC side?

Thanks and keep up the good work.
Jason

The inverter is a buck converter. It can turn high voltage, low current to low voltage higher current. The low speed power/torque will not change until the back EMF reaches battery voltage.

There has been talk that the Lexus inverter doesn't do field weakening, so power would fall off quickly at that point. It seems Toyota used the DC to DC converter (plus the MG1 generated power) on the high side to generate the 650V instead. Damien said he is taking the Bexus to a chassis dyno, then we will know for sure!

Potentially gearbox oil cooling could help.. is there a water cooling circuits for the motors?

drprox wrote: ↑Sun Mar 08, 2020 1:28 pm The leaf motor test concluded "Capable of operating at 80 kW continuously at 7,000 rpm with stator temperatures levelling out at about 135C".

Whilst the LS600h test results for MG2 found "50 kW operation at 5,000 rpm can be continued for 10:14 and 14:13 with stator temperature limits of 130ºC and 150ºC, respectively." The inverter appears to handle the power fine.

For everyday use both figures sound plenty. You'd have commit some serious road range to continuously use 50 or even 80kW. German Autobahn (with soon to come speed limit?) and race tracks would be the exception. WLTP cycle has an average power use of less then 10kW.
I didn't have the time to read the report, did they simulate the air flow caused by driving?

Lots BEXUS test drives today

philbrennan wrote: ↑Sun Mar 08, 2020 6:00 pm Potentially gearbox oil cooling could help.. is there a water cooling circuits for the motors?

Yes, there is a water jacket around the motors.

johu wrote: ↑Sun Mar 08, 2020 10:06 pm I didn't have the time to read the report, did they simulate the air flow caused by driving?

I don’t believe they did. For high load scenarios they used a coolant temp of 0C to try to keep the motor cool, but I don’t see mention airflow anywhere.

Also it appears (just as Damien said) that voltage won’t be an issue to run the full 10,230 rpms. Here are the back-EMF test results.

Ah, that's interesting, I missed that bit.

I can't understand why they bothered to run 650v in the actual car, it seems unnecessary.

Unless the high voltage actually for MG1 rather than MG2. I think in the Prius MG1 is very low torque but high RPM.

I estimated that with the input shaft locked in the GS450h transmission, MG1 should be running in the region of 2.5x the speed of MG2 due to the planetary.

MG1 is turning exactly 2.6:1 when the input shaft is locked.
78 teeth of ring gear, 30 teeth on the sun gear, so:
(78 + 30)Tc = 78Tr + 30Ts
Tc = turns of the planet carrier
Tr = turns of ring gear
Ts = turns of the sun gear
We know Tc = 0 with the input locked
78Tr = -30Ts
78/-30 = -2.6