Mornang

Hi!

Technically I was awake when you posted, but only just! 😉

Have we had a discussion about torque curves earlier?

You and me or the group in general?

group in general

Oh yes, plenty. Torque curves are the subject of one of my nicest answers on the site

So for me it's the hybrid that is the problem (in theory)

Modeling the curve of a hybrid system? Or just understanding what’s going on?

kind of both :)

the reason is that Polestar 1 claims to have 609hp

Short answer: it’s complicated 😉

but reading about it I see that those figures are just the individual engines max power added

Right. That’s not super helpful unless the control software allows that to happen.

yes. and I mean, not only software.. is it at all possible that they all have their maximum at the same place

The software is going to be all over this problem. If you’re just modeling what happens at max throttle from a stop, you might be able to nail things down

Electric motor should have pretty flat torque curve so peaks will come from the fuel motor

a flat torque curve yes (at least up to a certain rpm, but the power curve isn't flat

That’s because of the equation: HP = torque * RPM / 5252 (in ye old time units)

yes, so also a electric engine should have a peak power (right in the end of the torque top (if the rpm is > 5252)

Right. Electric motor should produce a power curve that looks like a line (it won’t be perfectly linear but much closer)

yes, linear, but not flat (or at least I took your flat as horizontal)

I’m seeing some charts online where electric torque begins to drop off at high rpms so the power has a peak that’s a bit before max revs

Right. Flat torque (until high RPMs). Linear power increase until high RPMs

I have seen this image for example: electrek.co/wp-content/uploads/sites/3/2017/11/…

unfortunately there is not RPM there, but it's interesting.

It is. Those discontinuities in the first derivative are thought provoking. They almost look like shift points

do you mean at both ~40 and ~70?

if this really is a correct curve.. then you have to wonder.. is it a coincident that the power turns flat? or is that by software?

Yes those.

You’d need to know how they measured those curves. Also, what model of control software was the tesla running. That could determine things like battery cooling and such that might affect ability to put out peak power

yes, but do you think this would be a normal curve for many ev's?

semanticscholar.org/paper/…

It’s really hard to say, especially since electric cars with transmissions are coming

yes the taycan have two gears

like this i.kinja-img.com/gawker-media/image/upload/…

I will laugh when the EVs end up with CVTs 😉

Might be the perfect application: put the devil’s transmission in an extremely efficient commuter car. 😉

I'm not sure about this idea......

But the power doesn't change with the gears right?

This curve is also interesting i.stack.imgur.com/mdd3R.jpg

Power (And toque) at the wheels does change with gears

@BobCross What? Ain't the torque on the wheels changed by gear?

yes it is, but at the same time the speed is reduced (?)

I’m talking about the difference between measured toque/power at the crankshaft vs measured at the wheels. The second one goes through the transmission so it matters what gear you’re in

For the single gear tesla model s, that’s a distinction without a difference since there aren’t other gear choices to select

about the tesla... the base model has about 400Nm...

but is that at the motor or at the wheels?

I would assume at the “crank”