Koenigsegg Dark Matter electric motor

[Micael]

I think this is a really neat and exotic electrical motor development. Koenigsegg has created it to be a part of the hybrid power train of their Gemera model.

IMG_7918.jpeg

First off it looks awesome, but it’s the tech and stats that’s the really neat bit. It’s a combined radial and axial flux design (Koenigsegg calls it ”raxial flux”), and everything on the inside is made from carbon fiber, rotor and stator included. Also, it’s a six phase design rather than the more common three phase designs.

The size of it is also impressively minute:

Height: 383.3 mm (~15 inches)
Width: 381.5 mm (~15 inches)
Length: 135.5 mm (~ 5 1/3 inches)

It weighs in at a modest 39 kilograms (86 lbs.)

In this humble package it delivers 800 hp and 1250 Nm of torque (~922 ft lb), maxing out at 8500 RPM. I’m sure there’s something else available in that neighborhood, but everything taken together with the stats, the looks, and even the name makes it seem so cool.

[warshipadmin]

Neat. I'm always a little puzzled by how they cool these big compact motors, even at 99% efficiency that's a fair bit of heat .

[Micael]

Neat. I'm always a little puzzled by how they cool these big compact motors, even at 99% efficiency that's a fair bit of heat .

Yeah, I gather it’s got a decent cooling system but I haven’t quite figured out the details of it. The six phase design is said to generate less heat than a three phase one does though so perhaps that helps a bit.

[Micael]

Related, here’s a twenty minute walkthrough of Koenigsegg engine and transmission production facility for the Jesko. Explaining the interesting bits about the engine and transmission, and showing it run a dyno test. It’s a very compact five liter V8 that puts out 1,280 hp run on 95 octane European (equivalent to 91 octane US), or 1,600 hp run on E85 (which is a high ethanol content fuel commonly available in Europe). The transmission is equally cool and peculiar, lacking a flywheel etc. I love engineering showcases like this, especially when it’s of cutting edge stuff:
https://youtu.be/TvVnSzFbv3c

Here’s another walkthrough of the Gemera drivetrain, 11 minutes long:
https://youtu.be/NdeCIo9yixo

[Edit] I should have added also that the second video, of the Gemera drivetrain, is of the most relevance to the thread start as it is the one to include the Dark Matter motor, and explains how the exotic drivetrain works as a whole and such.

[Pdf27]

The size of it is also impressively minute:

Height: 383.3 mm (~15 inches)
Width: 381.5 mm (~15 inches)
Length: 135.5 mm (~ 5 1/3 inches)

It weighs in at a modest 39 kilograms (86 lbs.)

In this humble package it delivers 800 hp and 1250 Nm of torque (~922 ft lb), maxing out at 8500 RPM. I’m sure there’s something else available in that neighborhood, but everything taken together with the stats, the looks, and even the name makes it seem so cool.

OK, so my day job is very relevant here - I'm the chief engineer for a similarly powerful motor/generator for use in Aerospace applications. Some comments:

1. Without the test conditions being explicitly stated, ALL of the values stated here are meaningless. A good example - electric motors typically have steady-state, 10 minute, 5 minute, 30 second, 1 second and sub-transient power ratings although not all will be quoted (the critical value is the integral of I2R dt versus the cooling circuit). The difference between these can potentially be in a ratio of 10:1 and we don't know which they are quoting or even if they've made their own rating up.
2. For context, YASA recently announced 738 HP from a 13.1 kg motor. Remarkably they actually announced the testing conditions on LinkedIn, which is really unusual.
3. Even weight values are of questionable utility - the photos shown are for a bare motor, not including the inverter - and how the inverter is integrated with the electrical machine has a huge impact on weight. Similarly with how it is integrated into the vehicle - how is the structural mass, rotor burst containment, etc. managed and is this mass counted against the motor weight?
4. "Raxial Flux" isn't a thing - it's an axial flux machine (probably related to the YASA/Mercedes design since they used to be YASA customers) where the rotor size has been tuned to take some advantage of the leakage flux at the edges. This is not unusual - technically the machine I work on qualifies for this, but I would never describe it as such since the impact of the secondary flux is minimal.

[Pdf27]

Neat. I'm always a little puzzled by how they cool these big compact motors, even at 99% efficiency that's a fair bit of heat.

It's oil flood cooling, with the oil in direct contact with all of the windings. The steady-state rating will also be a LOT lower than the transient rating: it's designed as a boost during acceleration, not for additional straight line speed so this is acceptable. That lets you use inertial cooling as well, which makes life a LOT easier.

[Micael]

The size of it is also impressively minute:

Height: 383.3 mm (~15 inches)
Width: 381.5 mm (~15 inches)
Length: 135.5 mm (~ 5 1/3 inches)

It weighs in at a modest 39 kilograms (86 lbs.)

In this humble package it delivers 800 hp and 1250 Nm of torque (~922 ft lb), maxing out at 8500 RPM. I’m sure there’s something else available in that neighborhood, but everything taken together with the stats, the looks, and even the name makes it seem so cool.

OK, so my day job is very relevant here - I'm the chief engineer for a similarly powerful motor/generator for use in Aerospace applications. Some comments:

1. Without the test conditions being explicitly stated, ALL of the values stated here are meaningless. A good example - electric motors typically have steady-state, 10 minute, 5 minute, 30 second, 1 second and sub-transient power ratings although not all will be quoted (the critical value is the integral of I2R dt versus the cooling circuit). The difference between these can potentially be in a ratio of 10:1 and we don't know which they are quoting or even if they've made their own rating up.
2. For context, YASA recently announced 738 HP from a 13.1 kg motor. Remarkably they actually announced the testing conditions on LinkedIn, which is really unusual.
3. Even weight values are of questionable utility - the photos shown are for a bare motor, not including the inverter - and how the inverter is integrated with the electrical machine has a huge impact on weight. Similarly with how it is integrated into the vehicle - how is the structural mass, rotor burst containment, etc. managed and is this mass counted against the motor weight?
4. "Raxial Flux" isn't a thing - it's an axial flux machine (probably related to the YASA/Mercedes design since they used to be YASA customers) where the rotor size has been tuned to take some advantage of the leakage flux at the edges. This is not unusual - technically the machine I work on qualifies for this, but I would never describe it as such since the impact of the secondary flux is minimal.

The test conditions and all the details haven’t been revealed yet as Koenigsegg doesn’t want to do that until a patent process has been completed. However Koenigsegg has historically been very open about details including showing test data, compared to most other car manufacturers. (See the dyno run of the Jesko power train towards the end of the first video.) They’ve also been very non-prone to deliberatly fudging stuff. As I understand it the Gemera hybrid powertrain dynos at 2,300 hp at the wheels with 1,500 hp from the V8 (with E85 fuel) and 800 hp from the electric motor. Typically Koenigsegg figures given like that refer to when running in a sustained manner. Hopefully we’ll see a full dyno run of that as well eventually.

Christian von Koenigsegg described ”raxial flux” as: "mostly axial, with a bit of radial flux—a radial effect on an axial flux layout."

The integration with the vehicle bit, there is at least some info on that. The full drivetrain is shown in the second video I linked above. If you have a moment to scroll through it at some point perhaps the visuals and your expertise can provide some answers that I’m unable to. What I can say is that it is mounted around the driveshaft.

[Pdf27]

The test conditions and all the details haven’t been revealed yet as Koenigsegg doesn’t want to do that until a patent process has been completed.

There is absolutely no reason to do this - you won't refer to any test conditions in patent filings. So they're trying to either hype things up or hide something.

As I understand it the Gemera hybrid powertrain dynos at 2,300 hp at the wheels with 1,500 hp from the V8 (with E85 fuel) and 800 hp from the electric motor. Typically Koenigsegg figures given like that refer to when running in a sustained manner. Hopefully we’ll see a full dyno run of that as well eventually.

None of the high performance hybrid vehicles quote steady-state power: The Gemera has a ~15kWh battery compared to a 500kW motor: at 500kW discharge rate that's 33C which is extremely high (and not totally realistic - the motor isn't a constant-power unit over the speed range) - you might get 5 kWh useable out of that battery at that discharge rate, and only be able to do it a few times before the battery gets too hot. That means for that battery you've got ~30s duration on the motor before you run out of battery - at which point the motor is absolutely not running in steady-state conditions. Typically (and this is VERY dependent on other requirements, such as maximum short-circuit current) a motor capable of 500kW for 30s will be able to manage about 200kW steady-state.

Christian von Koenigsegg described ”raxial flux” as: "mostly axial, with a bit of radial flux—a radial effect on an axial flux layout."

In other words, it's what anybody else would call an axial flux motor with some marketing stardust sprinkled on it. You always get 3D effects at the edge of the electromagnetics.

The integration with the vehicle bit, there is at least some info on that. The full drivetrain is shown in the second video I linked above. If you have a moment to scroll through it at some point perhaps the visuals and your expertise can provide some answers that I’m unable to. What I can say is that it is mounted around the driveshaft.

He does like his "never seen before" statements. For instance on a transmission layout taken from a 1950s family of British armoured vehicles with minor tweaks only.
In practice it's pretty much a bog-standard axial flux motor integration, with a load of mechanical gubbins sprinkled onto it. Placing an axial flux motor into a gearbox is usual, because they are short but wide - this means putting them standalone adds a lot of structural weight, but they're easy to fix into an existing structure.
They're using a single big motor which is pretty unusual - most people would use multiple motors and take advantage of the extremely fast control possible with electrical machines. They've gone with a mechanical solution instead - that's slow, but probably good enough for the application and is clearly being driven by the decision to allow them full functionality with the electrical system off. Not the way I'd do it, but good enough.

[Micael]

Christian has definitely got a pretty ”salesman” like personality, coupled with an obvious pride in what his garage startup company has managed to achieve over time. I think that this reflects in the verbage his uses.

The predecessor hybrid lineup where they used outside electric motors did have a three motor setup. I am not entirely sure, so could well be wrong, but in some other video I got the impression from the way that he put things that the decision to use a single electric motor had something to do with weight savings, and that the placement on the gearbox was somehow related to the deletion of a flywheel in the gearbox as the electric motor somehow acts as a substitute moderator instead. Possibly also related to the use of the motor as a starter motor for the V8, but I guess that it only has to be able to affect the crankshaft for that purpose and not necessarily have to be at the gearbox.

[Micael]

For anyone particularly interested I did manage to locate the patent for the hybrid drive train (but not anything on the electric motor itself yet):
https://tc.prv.se/spd/p/pdf/o5A4DQNLXlP ... vj5gfG4VzV