Max Rpm Gs450h

[Jackk]

I found a few people suggesting different max rpm limits for the GS450H.

Does anyone know the exact limit before I accidently explode mine. My current limit is set to 7500rpm and the car tops out at 70mph. Ideally I want quite a bit more revs but don't want to risk upping it until id ask...

The car is a 240z and feels very planted at 70mph. It could definitely do more!!

Thoughts?

[PatrcioEV-ATX]

I have mine set to 11k but I haven't hit that yet. The original user friendly software had it set at 10k. Most of the discussion in the support thread says 10-11k.

[Jackk]

I have mine set to 11k but I haven't hit that yet. The original user friendly software had it set at 10k. Most of the discussion in the support thread says 10-11k.

Thanks!

[Aragorn]

You can work it out from the mg2 ratio, rear diff ratio and tyre size of the gs450h and advertised max speed.

The gs450h tops out at 155mph. The rear tyre size appears to be 245/40r18 which does 785 revolutions per mile.

155mph = 2.58miles per minute * 785 gives a wheel speed of 2027rpm.

Rear diff ratio is 3.27:1, so gearbox output is running at 6608rpm

Mg2 high gear is 1.9:1 so mg2 is spinning at ~12500rpm when the factory car is doing 155mph.

[Jackk]

Ok understood,

Does anyone know if the rev limit within Zombie verter web interface records MG1 or MG2?

If its MG2 then MG1 would be spinning faster no? I'm worried if I set max speed to say 12500 then MG1 may exceed its max rating?

With my diff ration setup @ 3.545:1 I'm trying to get the max rpm I can out of the Gs450h to get decent speed.

[catphish]

Does anyone know if the rev limit within Zombie verter web interface records MG1 or MG2?

According to this line of code, Zombie only looks at the speed of MG2: https://github.com/damienmaguire/Stm32- ... 450H.h#L34

Code: Select all

   float GetMotorSpeed() { return mg2_speed; }

It's my understanding that MG1 spins faster (at least in high ratio), but I'm not sure of the exact ratio.

[Aragorn]

We cant easily figure out what the factory limits of MG1 are in the same manner as above, because MG1 speed doesnt directly correlate with road speed in a factory installation.

The PSD ratio seems to be suggested at 2.6:1

If thats the case then working from the above example, if the gearbox output is running at 6608rpm, then MG1 would be doing over 17000rpm.

I do not know if thats a safe speed for MG1. I also do not know if the PSD ratio is actually 2.6:1. Perhaps others can confirm.

[DkubusEV]

We cant easily figure out what the factory limits of MG1 are in the same manner as above, because MG1 speed doesnt directly correlate with road speed in a factory installation.

The PSD ratio seems to be suggested at 2.6:1

If thats the case then working from the above example, if the gearbox output is running at 6608rpm, then MG1 would be doing over 17000rpm.

I do not know if thats a safe speed for MG1. I also do not know if the PSD ratio is actually 2.6:1. Perhaps others can confirm.

This is the exact reason I'm planning (currently designing parts) to lock Mg1 to the output shaft and run it forward (not backwards via the psd) mg1 is normally tuning at engine rpm and therefore it probably never was intended to turn much quicker than the engine does at Max speed. It's a larger diameter rotor (more rotational forces pulling it apart at high speed) and because it's larger in diameter it can make significant torque at low rpm. So I'm not going to be using my psd. Instead lock it. This way it turns slower than mg2 the way Toyota intended. Plus internal oil pump will run too.

[Aragorn]

Certainly be interesting to see how you go about locking up the PSD, please post your progress, i'd love to see it!

Been thinking about similar myself to enable a third motor to be used.

[DkubusEV]

For sure once I have it sorted out I'll be posting how it's done and how it works. Hopefully it'll work out as planned...

[Jacobsmess]

I've seen 14,000 banded about as a max rpm for the gs450h transmission but no evidence for this, does anyone know the source of this?

[DkubusEV]

From my research I'm fairly confident that 14,400rpm is Toyota maximum for MG2 (smaller diameter rotor) as this motor runs through the planetary gearbox at rear prior to heading toward the diff it apparently good for "upto" about 100-140 kph in first gear (very dependent on your rear axle ratio) if you have enough voltage to spin the motor all the way to Max revs with enough current to actually push the vehicle. Second gear obviously will do Max speed of just over double that. (Given the same voltage requirements are met)... MG1 is significantly larger in diameter (and shorter in axial length) so it stands to reason that it absolutely can not be spun to the same or more speed than mg2 without risking a rotor failure (lifing magnets and or catastrophic rotor flying apart). In reality mg1 in the Toyota setup is really just "G1" it isn't used as a motor for moving the car in 99% of circumstances. It is primarily used to take torque from the ic-engine and convert it to electricity for use by mg2 via the "upto 650V" dc bus side of the inverter. And or send some to the battery storage via the "upto 30kW" dc-dc converter built into the top of the inverter. In standard hybrid format the psd (planetary) between mg1 and the ic-e is there to allow mg1 to "control" the speed of the engine vs the vehicle speed vs the load (torque required to wheels). The IC-E is not intended to rev beyond Max speed at Maximum highway speed (265kph??) So it is extremely likely that 8-9,000rpm is a maximum range for mg1 but if you lock the psd then mg1 will only ever turn at rear output shaft rpm (very safe rpm for mg1). This will reduce the total hp available from mg1 at anywhere under maximum vehicle speed at maximum torque current. But that's not a bad thing if you want efficient highway motoring.... cheers

[xp677]

Pretty sure its limited by mg1 and mg1 max rpm was 14000rpm. It was in my original code from 2020.

[DkubusEV]

Pretty sure its limited by mg1 and mg1 max rpm was 14000rpm. It was in my original code from 2020.

(Edited) planetary gear ratio is confusing.....

Whilst I don't have any test data to prove one way or the other I can see a couple of circumstances when mg1 would ever need to operate at anything nearly that high an rpm when working in the stock Toyota hybrid system, With the planetary gear power split device design the way it is built if mg1 was spinning at a "higher speed" than the engine was then the output shaft would spin slower?. So MG1 needs to have a higher rpm limit than the petrol engine so mg1 can lower the required engine speed for a given road speed OR the output shaft speed. Because mg1 is larger in diameter than mg2 it would have considerable additional centripetal forces acting on its rotor trying to rip it apart in comparison to mg2 at the same speed. Inertia is mean. So perhaps mg2 can rev 20% higher still??

I'm definitely not sure any more what mg1 speed limit is... ? Oh boy..

[Aragorn]

The problem as i see it, is there is not likely to be many situations where the car is driving at high speed, and the engine is stationary. Higher road speeds will need a decent chunk of power even for cruise, meaning the engine will need to be running.

Thus in the OEM application the MG1 is never likely to be operating at extremely high RPMs, and if it does reach those speeds, it wont be for long.

Theres a simulator here (albeit for a Prius variant which is slightly different): http://eahart.com/prius/psd/ You can play with the various speeds and see what you find.

High engine speed at low road speeds will see MG1 hit high RPMs, but ofcourse this will only be a transient situation (ie full throttle accelleration from stationary). Similarly low engine speed and high road speeds will do the same. Ofcourse this all depends on the interaction between the throttle request, engine ECU and hybrid system. It would be very easy for toyota to map the system to avoid those extremes, or ensure they are only short transients.

The text on the simulator page suggests exactly this, that MG1 has a software limit of 6500rpm, and the controller will start the ICE if it exceeds that. Which means (for that application) all road speeds above 42mph will have the ICE running to avoid excessive MG1 speeds even if power is not required (eg overrun). We dont know how exactly that translates to the GS450h box, but it does show that toyota manage MG1 speed with engine mapping.


The other issue is that it may not just catastrophically fail, instead it might just drastically reduce its life, and thats when things get really fuzzy, because you'll end up with a failed gearbox and not really know why, because it worked fine for n months/miles etc.

[DkubusEV]

The problem as i see it, is there is not likely to be many situations where the car is driving at high speed, and the engine is stationary. Higher road speeds will need a decent chunk of power even for cruise, meaning the engine will need to be running.

Thus in the OEM application the MG1 is never likely to be operating at extremely high RPMs, and if it does reach those speeds, it wont be for long.

Theres a simulator here (albeit for a Prius variant which is slightly different): http://eahart.com/prius/psd/ You can play with the various speeds and see what you find.

High engine speed at low road speeds will see MG1 hit high RPMs, but ofcourse this will only be a transient situation (ie full throttle accelleration from stationary). Similarly low engine speed and high road speeds will do the same. Ofcourse this all depends on the interaction between the throttle request, engine ECU and hybrid system. It would be very easy for toyota to map the system to avoid those extremes, or ensure they are only short transients.

The text on the simulator page suggests exactly this, that MG1 has a software limit of 6500rpm, and the controller will start the ICE if it exceeds that. Which means (for that application) all road speeds above 42mph will have the ICE running to avoid excessive MG1 speeds even if power is not required (eg overrun). We dont know how exactly that translates to the GS450h box, but it does show that toyota manage MG1 speed with engine mapping.


The other issue is that it may not just catastrophically fail, instead it might just drastically reduce its life, and thats when things get really fuzzy, because you'll end up with a failed gearbox and not really know why, because it worked fine for n months/miles etc.

100% agree, that makes lots of sense and it's similar (although better said and researched) to what I had originally written (and then edited). Thanks for explaining it the way you did. I'm now very convinced that going ahead with my "reversible" PSD locker "kit" is worthwhile and perhaps even the best possible use case for my particular builds at least. As I've bought two gs450h transmission's I'll be doing one of them "non reversible modified" with fully locked psd and shortened (removed) ice input shaft stub and a "sliced off" bellhousing for the most compact possible solution to allow more room for battery and other components. (Not like I ever plan on fitting an ICE or extra motor to that big diameter flange so it might as well be removed).

Cheers for your input and clarity of explanation. Thanks

[celeron55]

The rpm ratio of MG1 vs. MG2 is about 1.21 for me when running in second gear. E.g. MG2 8000rpm, MG1 9700rpm.

[DkubusEV]

The rpm ratio of MG1 vs. MG2 is about 1.21 for me when running in second gear. E.g. MG2 8000rpm, MG1 9700rpm.

You're running the ice input shaft locked I take it? What road speed are you doing at 9700rpm on mg1? Cheers

[Uppertown]

MG1 and MG2 clearly displayed and you can get an indication of road speed. Speed ratio appears to be 1:21 as Celeron says

[Aragorn]

yep, PSD is about 2.3:1 vs 1.9 for high gear, so MG1 is running around 1.2x faster than MG2.

[DkubusEV]

With the relationship between mg1 and mg2 (when ice input shaft is locked) and mg1 is being run in reverse in order to provide forward vehicle driving in combination with mg2 being run in normal forward rotation. However as this thread is trying to solve the question of "Maximum RPM of GS450H?" Then I guess the it possibly needs to be answered with two "versions" because with ICE-input locked MG1 will be the "max rpm limit" for the whole transmission output. (Meaning reduction in available rpm from the "main" motor MG2) as it will be impossible to reach mg2 max without overspeeding mg1!

As MG2 is the "main" traction motor in the standard hybrid set-up it makes sense to "try" to exploit its power (rpm) potential. This becomes especially important when you consider "usable RPMs" from a given level of battery voltage, most of us will be using less voltage than the standard hybrid dc-bus of 650V Meaning we will hit (at some point) a voltage imposed rpm/torque limit that will prevent further Acceleration. This will happen even earlier if mg1 is spinning faster than mg2 as it's larger diameter rotor will have higher "surface speed" within its stator winding and it will therefore produce more back EMF (generated voltage in opposition to inverter output). This reduces the current that the system can push through the winding once this difference in voltage between supply and motor has been reduced. If in fact Toyota designed mg1 to spin at a maximum of say 6500-7000 rpm (in normal hybrid car) then it's likely it's winding/magnetic relationship is optimised to "generate" the required 650v that mg2 will want from the inverter dc-bus when it's spinning at 14,400rpm?... (in the hybrid set-up at maximum load at high speed mg1 powers mg2 via the dc-bus with the ICE powering mg1 AND the output shaft via the psd planetary). The hybrid battery can only ever provide "up to" 30kW via the inverter mounted dc-dc converter. And of course at sustained high speed that can't happen for very long at all due to the tiny battery size.

So for ultimate max "usable" RPM from gs450h I believe it would be advantageous to use a rear axle ratio suitable for your desired top road speed that will allow mg2 to reach its maximum rpm (14,400rpm? Depending on available battery voltage) At your MAX road speed you would peak at. But only if you lock your PSD not the ice input shaft. (Or just don't use mg1 at all?) If gear shifts on the fly are tuned to be usable then mg2 on its own will be ample performance for majority of medium to light vehicles to struggle with traction from a standing first gear start... food for thought.

I'm working on psd locker kit. For my gs450h transmission's. Really looking forward to getting my project on the hoist asap.

Cheers for all the motivation and information guys!!
Mike.

[evMacGyver]

So for ultimate max "usable" RPM from gs450h I believe it would be advantageous to use a rear axle ratio suitable for your desired top road speed that will allow mg2 to reach its maximum rpm (14,400rpm? Depending on available battery voltage) At your MAX road speed you would peak at.

What advantages you think you will gain if you drive lets say 120km/h at 14400rpm? Or do you mean at maximum top (road) speed? Constant torque range of these motors will end somewhere around 5000rpm (?), after that there is less torque available. On higher revs maximum power will be constant while torque drops - at least in theory.

In my conversion I have set max rpm to 11k for both MG1 and MG2 and I've locked MG1 externally. On high gear at 5000rpm I get road speed of 103km/h, but with 11k limit I can rev MG2 up to around 9100rpm which is 188km/h, at that point MG1 will top at 11k.

I think keeping revs in mostly used road speeds within maximum torque range gives more benefits. I even could change rear axle ratios to diesel one, so that 5000rpm would give like 120km/h, which is maximum road speed here. And still I have low gear to use after we get gear change working perfectly.

[DkubusEV]

What advantages you think you will gain if you drive lets say 120km/h at 14400rpm? Or do you mean at maximum top (road) speed?

Constant torque range of these motors will end somewhere around 5000rpm (?), after that there is less torque available. On higher revs maximum power will be constant while torque drops - at least in theory.

In my conversion I have set max rpm to 11k for both MG1 and MG2 and I've locked MG1 externally. On high gear at 5000rpm I get road speed of 103km/h, but with 11k limit I can rev MG2 up to around 9100rpm which is 188km/h, at that point MG1 will top at 11k.

I think keeping revs in mostly used road speeds within maximum torque range gives more benefits. I even could change rear axle ratios to diesel one, so that 5000rpm would give like 120km/h, which is maximum road speed here. And still I have low gear to use after we get gear change working perfectly.

Absolutely I'm talking about Absolute V-max (not legal speed limit) so probably somewhere between 185-240kph at 14,400-MG2 rpm. Therefore highway cruising rpm would be just under half of peak rpm (depending on rear axle ratio).

Agreed 100% however torque won't (in theory) drop until the battery can no longer provide enough voltage over and above the motors "combined back-EMF" so by having mg1 (the higher b-emf motor) turning slower than mg2 the resultant "combined back-emf" is reduced allowing more torque for longer in the rpm band. (Plus reduced losses in mg1 windage (wind and oil turbulence) and zero losses into the psd planetary (because it's locked).

Personally I'm not wanting to rev mg1 beyond about 7k.

Again I 100% agree that keeping revs lower at cruising speeds is great for efficient motoring and transmission longevity (another reason to lock psd), because mg2 is designed to rev higher than mg1 it makes more sense to exploit that and keep your petrol rear axle ratio.

These are just all my opinions based on my research and governed by my strong intention to use the highest voltage battery I can make fit in my conversion so that I may run with as little current draw at "cruising" load as possible to further enhance efficiency whilst still having big potential for power and speed when I'm feeling like being "wasteful" (for fun)...

If I can work out the gear change programing and control the mg2 planetary clutches with absolute precision then I suspect that there is also possibility to disengage both gears of mg2 so that it can almost completely stop turning (and produce almost zero back-emf) when very low total torque is required at cruising speeds, mg1 would therefore be the only motor driving the vehicle and at very low rpm (locked psd means mg1 rpm = output shaft rpm).... basically a "third gear" (operating method) for extreme efficiency driving...

*in theory*

Hopefully it all works out.
Cheers