Here is a nice video that explains axial flux motors with a factory visit
https://youtu.be/B2Hl4c1iZK0?si=VfDYARyuaPVj1nKm
They are so, so, small.
What did you like most about it?
Also I have "The Way Things Work" on my desk right now and can't help but wonder, could you adapt some of the pages of the book this way? It seems like exactly the kind of content that would benefit from such 3D (interactive) visual explainers.
The visuals didn't show much, and I learnt a lot more from one of the YouTube videos (https://www.youtube.com/watch?v=dCO633KE7RA) posted below.
It's neat that a whole interactive deck can be produced without effort. But it's just not very interesting.
Is that right? One could get ~200hp from something the size and mass of a small dog?
WOW, pretty cool!! :-)
Esp.if you scroll etc. Impressive.
When these hopefully go to the next generation Formula E cars, we’ll see some crazy improvements in cornering. The newest generation already has active 4WD. I imagine this can bring even better torque adjustment improvements.
Secondarily power electronics; at that scale, you can't just pick a bigger transistor and call it a day.
By comparison the motors seem to be a mostly solved problem, although I'm sure there's still some scope for power-to-weight engineering there, it's not as critical as the battery pack.
It's not like the Dawn of the steam engine
All the industrial processes and machine tool development that happened in the ICE car industry over the last century (and the electronic hardware manufacturing, more recently) was available day one.
China has industrial policy. The country and companies are able to invest in BEV technology knowing that everyone agrees on the direction.
The talent had very little impact to be honest. The primary factor was a government looking 50 years down the road seeing that:
1. ICE engines have little to no long-term future in transportation.
2. global warming is a thing whether the right wing in the US likes it or not.
3. They were never going to overtake the West in ICE engines and had to attack from a different angle.
The US' lack of breakthroughs in EVs has little to do with technology or expertise and everything to do with an administration that is openly hostile towards EVs and renewable energy in general. For the rest of the planet, EVs becoming the primary form of transportation is just an obvious and logical conclusion, even if it takes us another 25-50 years to get there.
China saw it and decided to heavily incentivize and subsidize the rapid expansion of EVs both to fix the air quality issues in China and corner the market.
How do you know this for a fact? Chinese press releases? You've driven one? Some auto blogger drove one?
After world war 2 Gorbachev or whoever visited the United States and during that trio visited a supermarket. He thought it was a facade, possibly, put on just for him, there's no way Americans are this prosperous (or whatever, this good at agriculture, farm equipment, etc)
Also do the race cars have 4 wheel drive, or all-wheel drive? I'm wagering all-wheel with "torque vectoring" and "Yaw control", like a Mitsubishi Lancer Evolution X.
So it looks like axial flux, the OG was introduced in 1820 something and it wasn't easy to manufacture. So radio flux came after that and has been around ever since. So axial flux is making its come back this year!
The video is very interesting too about decompounding returns when the motor is less with the other things need to weigh less too.
Especially the bit about potentially not needing brakes in the near future because the regen is so capable. Which would lead to less weight and less parts even again!
Edit.... Video doesn't seem to explain very well either
"In contrast to conventional radial flux motors, the electromagnetic flux in an axial flux motor runs parallel to the axis of rotation. The key components are arranged in a disc‑shaped layout: two rotors sandwich the stator from the left and right. This design enables an especially compact motor architecture, high power and torque density, and new freedoms in drivetrain packaging. In the new Mercedes‑AMG GT 4‑Door Coupe, the motor at the front axle is just under nine centimetres wide; the two motors at the rear axle each measure around eight centimetres in width. The three axial flux motors are integrated per axle into so‑called High Performance Electric Drive Units (HP.EDU), where they are combined with a compact input planetary gearbox in a single housing."
Hand waving.
Edit: a video from them on this particular YASA tech being discussed : https://youtu.be/m507ryWhc6c
> In contrast to conventional radial flux motors, the electromagnetic flux in an axial flux motor runs parallel to the axis of rotation. The key components are arranged in a disc‑shaped layout: two rotors sandwich the stator from the left and right. This design enables an especially compact motor architecture, high power and torque density, and new freedoms in drivetrain packaging. In the new Mercedes‑AMG GT 4‑Door Coupe, the motor at the front axle is just under nine centimetres wide; the two motors at the rear axle each measure around eight centimetres in width. The three axial flux motors are integrated per axle into so‑called High Performance Electric Drive Units (HP.EDU), where they are combined with a compact input planetary gearbox in a single housing.
I wonder why they need tree motors per axle.
https://www.instructables.com/Designing-and-Building-an-Axia...
https://en.wikipedia.org/wiki/Axial_flux_motor#Automotive
> Mercedes-Benz subsidiary YASA (Yokeless and Segmented Armature) makes AFMs that have powered various concept (Jaguar C-X75), prototype, and racing vehicles. It was also used in the Koenigsegg Regera, the Ferrari SF90 Stradale and 296GTB, Lamborghini Revuelto, McLaren Artura and the Lola-Drayson.[9] The company is investigating the potential for placing motors inside wheels, given that AFM's low mass does not excessively increase a vehicle's unsprung mass.[10]
> In July 2025, YASA announced a prototype 550 kW (738 hp) 13.1 kg (29 lb) motor, equating to power density of 42 kW/kg, which the company claimed to be the highest ever achieved.[11] By contrast, the state of the art EV motor from Lucid Motors offers a 500 kW, 31.4-kg motor, or 16 kW/kg.[12]
> The first application of these motors will be in the High Performance Mercedes‑AMG GT 4-Touring Coupe.[14]
Designing the manufacturing machinery is exactly what happens in any manufacturing process. Those robots are general purpose that have been adapted for the required tasks, that's a normal process.
Why would you build a motor that's twice as heavy with copper and much wider when you don't need to?
What is the current market sentiment? Share of EVs is slowly rising so having a good motor as important as ever.
Is Mercedes stupid?
How did Carl Benz dare to do something as hideously complicated as building the first gasoline-powered car in history?
And why did they kept inventing complicated stuff that ended in all modern cars like ABS, adaptive cruise control, direct fuel injection, emergency brake assist, etc, etc?
My main gripe with MB is that they have this new technology that could simplify things and let them build a better product. Instead of building around it, they shove it in to their existing designs. I was expecting an electric S class to be more akin to a Lucid Air sans the teething problems of a new company. Instead, we get weak attempts at solving non issues.
And whilst they are certainly not in the market of producing affordable vehicles, I would hope that using EV tech they could create a better version of their existing fleet. I do not think anyone buying an A class cares about the 4 popper under the hood - losing it and simplifying radically, in my mind at least, would give them more budget and leeway to create a more compelling product.
https://de.wikipedia.org/wiki/Datei:Wiesloch_Stadtapotheke_E...
For example, can a car with 200kW propulsion have a 400kW regen (Tesla has upto 65) and are cost effective like friction brakes?
In order to generate a higher regen, you'd have to somehow get more energy in the motor first... and since its only rated for 200kW, good ol' physics limits you, IF thats all the energy you put into the system.
If you roll it down a hill, or do something exotic like inverting the magnetic fields .... you can exceed the motor rating. But thats usually not recommended because the motor driver itself isnt rated to handle that power.
At the motor level it should be the same, in propulsion you’re converting current to torque and in regen you’re converting torque to current, with the same hardware. The high voltage wiring is the same and will set the same limit on current regardless of direction.
I believe bidirectional inverters are generally symmetrical as well, so that should not be a factor.
Which I reckon leaves two factors:
1. Battery C rates, afaik pretty much all chemistries have a higher discharge rate than charge rate, especially when trying to maintain them for a long time, so by that account regen power would at most be the same as propulsion (if the entire power train is sized for the battery’s charging rate).
2. Artificial limitations, obviously you could always artificially under-prop, though that seems unlikely outside of niche applications.
tldr: I don’t think so, except on a technicality (that you can artificially hobble propulsion).
And 400kW isn't really all that much for a sports car. I remember 911 ads from the '80s that boasted "brakes with more than 1000 horse power".
Personally, I'd rather see FWD with 1 100HP motor in a 2200-lb 4-seater under $20K US, but that will never happen as the supply is artificially constrained to create high-end cachet.
The main advantage of this is cost, not weight or performance, but it does show that EVs have different profile to ICE cars.
I'd personally prefer a belt-and-suspenders approach.
Brought to you by the only country to have a space programme and abandon it.
I mean, so did France; they both essentially folded theirs into ESA.
For example Siemens and Bosch are large enterprises specialised in industrial scale electrical machines and parts (among other fields).
Infineon was spun off from Siemens 25 years ago an plays an important role in chip manufacturing for automative systems.
Software and battery cells are the main challenges.
Unfortunately, most modern engines are transverse mounted. They can fit any transmission with an adapter plate, but then they're set too far back into the firewall to access stuff like the high-pressure fuel pump (which is often mounted on the transmission side for easy access on front wheel drive vehicles). I feel that's by design for planned obsolescence.
So I really wish that someone would offer a 4-6" thick 100-200 hp (100 kW) axial flux motor insert between the engine and transmission. Optionally with a simple battery management system (BMS) storing perhaps 5 kWh to provide up to 15-20 miles of electric range and hybrid fuel economy with regenerative braking.
If anyone knows of one, please let us know! If not, then those of you who won the internet lottery could make a killing investing in a novel product that everyone wants but doesn't know it yet.
Totally with you, I want more options for my Tacoma also!
I’ve been playing with idea of importing a lhd hilux from Mexico
1) torque: torque = applied force x length of the lever. Because the radial flux rotor must fit inside the stator, therefore radius << motor outside diameter. With the axial flux motor, the rotor is adjacent to the stator, therefore radius < motor outside diameter. Axial rotor radius > radial rotor radius.
2) space efficiency: in a radial flux motor you have 1 rotor, the coils arranged so that one end of the coil's magnetic field is useful to work on the rotor, the other end is not used. In an axial flux motor, (1) pancake rotor at each end of the coils, total (2) rotors, the coils can act on a rotor at each end. There is no free lunch here, to do useful work you still must provide more energy to the coil, but you can get the most from the space.
There must be someone here with a better handle on the electromagnetism, please correct me where I err.
The area of the top+bottom is (2 * pi * radius * radius)
The area of the wall is (2 * pi * radius * length)
For them to have equal magnet area, you need length to be equal to the radius, which is bad. That makes your motor really thick. In the axial design, you can make the motor thin and still have the same magnet area as before, so your motor now weighs a lot less.
Personally I’d love to see this make it’s way into power tools and CNC motors.
This makes them kind of unsuitable for power generation and really high power motors (despite their power density) where the main way you get more power is just to spin really fast.
The other disadvantage is they have such a low amount of material in them, that the stator overheats really easily. And the topology of the motor makes it really difficult to get the heat out efficiently, which again limits their maximum power.
I expect radial will still dominate for at least another decade or so outside of premium performance focused cars. Radial has been battle-tested and proven. Axial still has a few more years to prove it's reliability in the field. Higher loads and stresses, tighter tolerances could make the axial motors less reliable overall especially at mass market trims. Mercedes is probably over-engineering for reliability and performance on the premium car
Radial is also "good enough" for most applications. The efficiency, form factor and weight improvements of axial is nice, but they aren't the limiting factor. Radial is already highly efficient, reasonably light and small. The real level for weight is the battery
Advancements here chip away at margins, its nice but nothing to get super excited about. Whereas a modest ~20% increase in energy density from batteries would be amazing. Every little bit we improve there unlocks new capabilities. Towing long distances, smaller affordable economy cars and sports cars, airplanes, etc.
> In the Coupé, the engine on the front axis is 9 cm (3.5 inch) wide, the two engines on the rear axis are 8 cm wide each (<3.2 inch).
> The fully electric "Performance" model accelerates from 0 to 100 km/h in 2.1 seconds.
ETA: Images of the engine:
https://media.mercedes-benz.com/article/bebac2af-acdc-465a-9...
https://media.mercedes-benz.com/article/bebac2af-acdc-465a-9...
That's incredible.
https://news.ycombinator.com/item?id=31701133 Inside Yasa: how a British firm is revolutionising electric cars (2 points | 0 comments)
About once a week I think I'm too dumb to be on this site and today is that day. Off to duckduckgo to do some research.
Edit: it's actually pretty simple. Here is the wikipedia on them:
https://en.wikipedia.org/wiki/Axial_flux_motor
It could use some more diagrams, but it makes the gist of it pretty simple to understand.
Amazing what materials science achieving to get this sort of power as well as the engineering and manufacturing.
If you’re not caught up https://youtu.be/m507ryWhc6c?si=Hq3dfjXYxEIlYzeo
(The motor is less important than the battery in terms of total weight, long term durability, etc. But nonetheless, any improvement helps!)
https://english.cas.cn/newsroom/cas-in-media/202606/t2026060...
Their motor is pretty cool. So are lots of other ideas and concepts. This is supposed to be about production. Arguably, the coolest thing about Yasa is the machines and process they have created to produce their motor in production quantities.
It disappoints me when an article promises to be about production but seems more to be a press release about the product.
I wish them well and would be excited to learn more about their actual production capacity.
