Damien takes Zombie GS450h on dyno

[Bigpie]

For those looking to know what to expect, performance wise, with a GS450h

[Pete9008]

No that's a pretty good result

What I'm curious about is whether there is something different about the 450h motors that allow them to make such good power at normal pack voltages (compared to the rx400h, mgr, Prius, etc) or is there something clever being done by the Lexus inverter that we don't do in the OpenInverter code?

[celeron55]

I'm sure it's Toyota's algorithms doing the magic. Even in 2006 when the GS450H went into production they already had a decade of time to develop their inverters.

[kiwifiat]

The rx400h has a smaller air gap area and thus significantly less capable of producing the same power as a GS450h motor. The GS450 is similar in size to a Nissan Leaf motor according to the engineers at Oak Ridge National Labs in the US. Secondly since mechanical power is the product of angular velocity and torque then the smaller rx400 motor is handicapped in that it has a very low Kv or high Ke by design since it was never designed as the main tractive power provider. Think of in terms of the glory days of formula 1 1.5L 4bar turbo engines producing 1000BHP and running to 20,000rpm. It is that angular velocity aspect of power production that is the driver for Tesla latest 18,000 rpm plaid motor in my view. Given enough voltage there is no doubt that the rx400 motor would perform on par with the gs450 motor on an air gap area basis but it will never match it on raw output power.

I don't believe that there is any magic going on with the Toyota inverters. The requirements for maximizing power production in three phase permanent magnet synchronous motors is well established and at a minimum requires accurate knowledge of the motors inductance, rotor angle, and phase currents. Without accurate rotor angle information it really is impossible to achieve optimal performance which I guess is why all the major OEMS choose resolvers and dedicated resolver to digital chips for that task.

[Pete9008]

Agree with all that

Bear in mind that rpm is just one way to make power and is normally best when low weight is the priority and lifetime is less off an issue. The other way is torque but tends to produce a much bigger, heavier solution that has a longer working lifetime (think big marine or truck engines).

Do you have a link for the Oak Ridge report with the GS450h and rx400h air gap details? I thought I'd read all the relevant ones but don't remember seeing that so may have missed one.

Also interested in the inductance and flux linkage values for the GS450h motors if anyone has them? I'm curious about what the difference is compared to the rx400h.

[hazelnut]

I just got a (running) GS450h. It is a very, very fast car. The book states 349hp, with the engine providing around 300. It is my understanding that all the engine power goes into MG1 -> 650V then MG2 takes some additional current from the battery to top up to around 250kW. So in theory the GS450h MG2 is good for 250kW and MG1 should be good for 200kW so running both together could make 450kW ? However having driven the car around, anything above 100kW is more than enough for a public road. I would expect with MG1 and MG2 running together at max current at 350v to generate around 225kW, so allowing for driveline losses the rear wheels would see around 190kW or 255BHP. So pretty close on the Dyno.

[rstevens81]

It's actually the 600h gearbox ornl did the test on but it's the same except the transfer box...here it is anyway
https://www.google.com/url?sa=t&source= ... p_aA1ec3sC

[Aragorn]

I just got a (running) GS450h. It is a very, very fast car. The book states 349hp, with the engine providing around 300. It is my understanding that all the engine power goes into MG1 -> 650V then MG2 takes some additional current from the battery to top up to around 250kW. So in theory the GS450h MG2 is good for 250kW and MG1 should be good for 200kW so running both together could make 450kW ? However having driven the car around, anything above 100kW is more than enough for a public road. I would expect with MG1 and MG2 running together at max current at 350v to generate around 225kW, so allowing for driveline losses the rear wheels would see around 190kW or 255BHP. So pretty close on the Dyno.

Not quite.

In normal operation, engine power comes into MG1/Power split device. MG1 applies a braking force to the PSD by acting like a generator. In this situation, some of the power is transferred mechanically by the PSD, and some is absorbed via MG1 thru the inverter and fed back to MG2.
I dont know the proportions.

[Aragorn]

I guess its one of those tests that for me actually opens up more questions...

The current limit on Damiens car is 500A from memory. 500A and 350v is thereabouts 175kw or 235hp.

So that matches up fairly well with what he measures.

The time it takes to get to peak power would be a concern for me. A factory LEAF for instance is at full power by about 30mph, a Tesla is at full power by about 40mph. The plot suggests its not hitting the ~200hp figure here until about 70mph.

It would appear to be sitting against a torque limit from the start of the pull to when it hits the peak. We can see it makes 220hp at 123kph and 110hp at 62kph, exactly half, suggesting exactly the same torque value. Can we request more torque from it?

I guess my question is, what exactly is the limiting factor here? Can we turn up the current limit? Can we request more torque earlier in the RPM range and hit that current limit earlier? Are we limited by the actual motors? Or the Lexus inverter firmware? or the batteries?

If you have one of these boxes and want say 250kw from it, what exactly needs to be done to achieve that?

[rstevens81]

The 500a is limited by the Toyota inverter firmware, it's true Damian could get full power at lower mph, however he has a diesel diff back from when he had a big DC motor, diff swaps are not easy as different fittings are are different diffs on BMws (Damian learnt that the hard way) with the torque that the motor produces it more than most would ever need and first gear produced so much torque it spun wheels on the Dyno!

[Aragorn]

Yeah I'm sure it's plenty power for a passenger car. Anyone know the diff ratio used so we can correlate the recorded speed with motor rpm?

Ive been contemplating one for a more utility application. Pickup or SUV used for towing etc. Current vehicle has a 220hp v8 and it really struggles when pulling a trailer. Ofcourse some of that is down to the fact that the engine isn't making 220hp at normal driving rpms, but that's why it's also a concern that this isn't making the power until high speeds either.

The gear switching is a fair point though. Being able to drop into low range would help significantly.

[catphish]

It would appear to be sitting against a torque limit from the start of the pull to when it hits the peak. We can see it makes 220hp at 123kph and 110hp at 62kph, exactly half, suggesting exactly the same torque value. Can we request more torque from it?

This is pretty much what you can expect from any electric drivetrain. They produce constant torque from a standstill up until they run out of voltage (in this case at 123kph). I'm sure Damien was running his at 100% torque during the test.

My subjective experience is that when it comes down to it, nobody has felt it necessary to use the low ratio of the GS450H. Most people are running light passenger cars and actually want a higher ratio because they have mountains of torque but quickly exceed the RPM limit. Of course your case with a truck will be a bit different.

I personally find horsepower to be a really useless measure. The fact that a GS450H is making zero horsepower when it launches the car doesn't seem to impact its ability to do so rather rapidly. In my experience, the best way to compare an electric motor to a petrol engine is this:
1) Work out which gear is roughly equivalent, ie which gear redlines the engine at around 75mph
2) Feel the *peak* acceleration you can achieve in that gear (ie near the redline)
That is that your acceleration will be like at all times with the electric motor.

[kiwifiat]

Do you have a link for the Oak Ridge report with the GS450h and rx400h air gap details? I thought I'd read all the relevant ones but don't remember seeing that so may have missed one.

No I don't sorry, air gap area times rotor radius is a useful metric for indicating torque production capability but you need to calculate it yourself. I had a crazy idea of building a new rotor for the gen2 Prius out of two Camry rotors based on the fact that they are capable of much higher rpm, 14,000rpm v 6000rpm.

[Aragorn]

This is pretty much what you can expect from any electric drivetrain. They produce constant torque from a standstill up until they run out of voltage (in this case at 123kph). I'm sure Damien was running his at 100% torque during the test.

My subjective experience is that when it comes down to it, nobody has felt it necessary to use the low ratio of the GS450H. Most people are running light passenger cars and actually want a higher ratio because they have mountains of torque but quickly exceed the RPM limit. Of course your case with a truck will be a bit different.

I personally find horsepower to be a really useless measure. The fact that a GS450H is making zero horsepower when it launches the car doesn't seem to impact its ability to do so rather rapidly. In my experience, the best way to compare an electric motor to a petrol engine is this:
1) Work out which gear is roughly equivalent, ie which gear redlines the engine at around 75mph
2) Feel the *peak* acceleration you can achieve in that gear (ie near the redline)
That is that your acceleration will be like at all times with the electric motor.

The useful thing about power is its speed agnostic. Power is the end result of speed and torque. You can have lots of torque and low speed, or lots of speed and low torque and achieve the same end result. Torque alone is useless.

In a production EV, say a LEAF, by ~30mph your sitting at the power limit and its producing 110hp continuously, which is great. It makes the car much quicker than a 110hp ICE would be, because its producing 110hp non-stop, rather than the ICE which is only producing 110hp at the top of each gear, and dropping away from that with every shift.

However looking at the curve here, we're not producing 220hp continuously. Its much more like an ICE would be, because it takes until 70mph to actually reach 220hp. Basically it entire normal/legal operating window its making less than 220hp. The missing piece of course is gearing and motor RPM. If we can gear it down and get to peak power earlier that would ofcourse help things significantly. Or, i guess, run more voltage, as if the limiting factor is the inverter current limiting to 500A, then more voltage should raise the whole curve. That creates its own issues though, as many of the anciliary components arent that happy running over the typical 96s range.

One interesting difference i noticed when comparing the OEM L110 and L210 installations, is the L110 is geared for 155mph in the GS450h. The L210 however is geared for only 120mph, i guess allowing them to extract a more useful operating window from the motor. I'd happily gear it down to 100mph or maybe even a touch less, need to be mindful that the motor probably wasnt designed to run at maximum RPM continuously though.

[catphish]

The useful thing about power is its speed agnostic. Power is the end result of speed and torque. You can have lots of torque and low speed, or lots of speed and low torque and achieve the same end result. Torque alone is useless.

I respectfully but strongly disagree. Having driven an EV off the line at full throttle and zero horsepower, I can assure you that (wheel) torque is the only thing that matters. You talk about the constant power region like it's a good thing, but generally you don't want to be in the constant power region, as you're losing torque in order to gain speed.
I would argue that torque is in fact the variable that is speed agnostic.

Edit: I should add, obviously the overall issue of gearing (tradeoff between more top speed and more torque) is always going to exist. However, the point I'm trying to make is that you don't need *power* at low speed, it's almost always preferable to have constant torque for as much of your normal driving range as possible.

[Pete9008]

I'd agree with catphish here. Power is best for bragging rights but torque is what makes a car feel responsive/quick. The trouble is that on ICE engines it is always engine torque quoted while it's wheel torque that matters. It's difficult to compare engine torque because of gears so power is always used despite it being less useful in many ways.

For a road car my ideal would be for the transition into the constant power region to occur at the max legal speed to keep the car feeling as responsive as possible in normal use, i.e. always run in the constant/max torque region. My concern is that when you enter constant power it's going to start to feel like an ICE engine that has revved past peak torque and you will constantly feel the need to change gear but can't.

If you want to have more power available at lower speed put the L110 in low gear, it will make more torque at the wheels then too

[SuperV8]

I guess its one of those tests that for me actually opens up more questions...

The current limit on Damiens car is 500A from memory. 500A and 350v is thereabouts 175kw or 235hp.

So that matches up fairly well with what he measures.

The time it takes to get to peak power would be a concern for me. A factory LEAF for instance is at full power by about 30mph, a Tesla is at full power by about 40mph. The plot suggests its not hitting the ~200hp figure here until about 70mph.

It would appear to be sitting against a torque limit from the start of the pull to when it hits the peak. We can see it makes 220hp at 123kph and 110hp at 62kph, exactly half, suggesting exactly the same torque value. Can we request more torque from it?

I guess my question is, what exactly is the limiting factor here? Can we turn up the current limit? Can we request more torque earlier in the RPM range and hit that current limit earlier? Are we limited by the actual motors? Or the Lexus inverter firmware? or the batteries?

If you have one of these boxes and want say 250kw from it, what exactly needs to be done to achieve that?

The Plaid doesn't reach it's 'max power' until around 70mph! I don't think anyone would be concerned by this.
The speed at which you reach max power can be changed by your gearing/tyres.
Electric motors indeed have a torque limit usually imposed by the current rating of the inverter.

[Aragorn]

I mean you can take extremes.

Motor 1 makes 1000nm, but has a power limit of 10kw

Motor 2 makes 100nm but has a power limit of 300kw.

Which ones going to accellerate you to 60mph faster?

[Pete9008]

It depends how you gear them! (wrongly geared the 300kW motor may not even make 10kW by 60mph)

But you've just demonstrated why power is the normal metric

[catphish]

Motor 1 makes 1000nm, but has a power limit of 10kw

Motor 2 makes 100nm but has a power limit of 300kw.

Good question.

The motor with crazy high torque will accelerate you insanely fast off the line, but only until it reaches its peak power, which will obviously happen extremely quickly. My guess is that it will enter constant power region at around 5mph and above that torque will drop off dramatically.

Motor two will accelerate you gently but very consistently up to a much higher speed.

Both of these motors suck of course.

The most basic point remains, acceleration is directly proportional to torque.

Therefore at lower speeds, you will be running the motor at its peak torque. Once you run out of voltage (ie reach peak power) and enter the constant power region, torque (and hence acceleration) are reduced as speed increases.



Note that you get much more torque (and hence acceleration) at lower speed when you're not using all the available power. Again, there is of course a trade-off with gearing. You could gear it lower, and get even more torque, and run into the power limit even sooner. The downside is you'd lose top speed, and usually nobody wants all their acceleration concentrated into the very bottom of their speed range.

[Aragorn]

I guess simply stating one or the other is more important doesnt work. What matters is area under the curve.

Getting to 200hp earlier, and holding that figure throughout the pull, puts more area under the curve and produces a faster car. To achieve that you either need more torque, or more RPM's (and different gearing)

Using the graph above (can scale it 10x to make it more realistic for a car but it doesnt really change the curve) The graph shows what i would expect to see. Peak torque at about 1/3rd max motor speed. If that motor was geared to max out at 90mph, you'd have peak torque at 30mph ish and fairly constant power upto 60-70ish. Which is fairly representative of where most commercial EV's end up i would think? Probably with the exception of high end stuff like Plaid teslas and taycans and the like.

Drop the torque to 30 and then maintain it all the way out to 6000rpm instead gives something more akin to what the GS450h plot seems like. It still gets to the same peak figure, but spends much longer in the torque limited zone.

Anyway, i didnt want this to devolve into an argument, my initial questions were about the technical aspects of whether its possible to get anything more out of it. Evidently to achieve that we would need more torque, and the limiting factor for that is the factory inverter firmware.

Does make me wonder how a full open inverter board (prius gen3?) driving the inverter would fare with the ability to push things harder.

It might also be an interesting exercise to plot wheel torque of a typical ICE as it moves thru the gears/speed range, and see how that compares with a particular proposed motor/gearing combo.

[catphish]

I guess simply stating one or the other is more important doesnt work. What matters is area under the curve.

Getting to 200hp earlier, and holding that figure throughout the pull, puts more area under the curve and produces a faster car. To achieve that you either need more torque, or more RPM's (and different gearing)

Yes, I agree entirely here. By using lower gearing you reach peak torque sooner and ultimately you get more in total, at the cost of a lower possible top speed.

Edit: don't forget, torque is also limited by the tyres. There's only so much you can reduce the gearing before you simply can't keep the car on the road

[Aragorn]

Anyone know the diff ratio used so we can correlate the recorded speed with motor rpm?

Pushing some numbers around.

Damiens (much!) earlier video suggests he installed a 2.81:1 rear diff from a 530d.

The dyno pull tops out around 100mph, with the 1.9:1 gear in the transmission, that suggests that MG2 was only turning around 7000rpm at the top of the run.

If those numbers are right, it certainly explains why it seems late to reach peak power. Its just geared very tall. Probably wants something in the 4:1 range to get the RPM's up.

[rstevens81]

What everyone seems to miss is the gs450h is a torque monster and playing with diff ratios doesn't make much difference when you can't use it even in a tank like the e39

[Aragorn]

What everyone seems to miss is the gs450h is a torque monster and playing with diff ratios doesn't make much difference when you can't use it even in a tank like the e39

Messing with wheel torque calculations, i'm just not seeing it?

From the numbers i'm looking at here (best guess ofcourse based on published figures) a RWD ID.4 puts down circa 4000nm wheel torque from start upto whenever it hits the power limit (info is vague but assuming its all pretty linear, somewhere around 5000rpm or ~35mph).

This dyno pull suggests the E39 is putting down less than 2000nm wheel torque given the diff ratio guess above and various assumptions (ie factory tyre size and the dyno speed plot being accurate)

Perhaps my numbers arent perfect and i'm happy to be corrected if i've missed something?