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Mercedes‑Benz starts large‑scale production of electric axial flux motor

media.mercedes-benz.com

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Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#351

Post by lazide »

dotancohen wrote: post #343
lazide wrote: post #322

Earlier quoted context omitted.

Brazilians got a bunch of them and they are super common in Brazil. Also common - broken suspension parts from driving them in Brazil. Also, the only cars I’ve ever ridden on that the top of my head literally touches the headliner while sitting in the back seat. Other than that, they seem good?

Great to know, thanks. Israeli roads are typically well maintained, but I'll keep an eye out for suspension damage. In this Atto 3, I've ridden in the back a few times and my head does not touch the headliner. I'm 170cm.

Yeah, I’m 182+ cm, so a bit bigger. It still surprised me. BYD Dolphin if I remember was the worse.

The suspension issues seem like a common theme though, they aren’t built as sturdily as most cars on that front.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#352

Post by ElijahLynn »

IrishTechie wrote: post #275
ElijahLynn wrote: post #187

Earlier quoted context omitted.

Great video! 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 th…

Also found it fascinating, although on the discussion about brakes I thought about how regen braking turns off in my EV when the battery is full, because there is no where to put the power. So you either keep some of the battery always available to soak up braking energy (and hope people never charge to full at the top of a mountain and exhaust the buffer) or you include a set of normal brakes for when regen is not p…

Interesting, it seems like keeping the battery at some level below 100% (e.g. 80%) would make sense then because I don't think regen would ever top it off that much right?

My understanding is that after 80% the rate of charge a lithium ion battery can accept diminishes.

Could the 80% Li-on battery accept the charge from the brake regen fast enough? Or would it still have to be drained somewhere else if the battery could not accept it?

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#353

Post by chrisweekly »

Gracana wrote: post #144
chrisweekly wrote: post #81

Earlier quoted context omitted.

In terms of traction control, does this translate to something between "4WD" and "AWD"? Or is it orthogonal?

Kind of orthogonal. Traditional AWD and part-time 4WD systems are solutions to get power from a single motor to both the front and rear of a vehicle. AWD has a center differential to account for differences in front and rear driveshaft speeds when driving on high-traction surfaces. 4WD just locks the front and rear driveshaft rotation together, which is a simple and robust solution that only works on loose surfaces.…

Thanks! Makes perfect sense. Great explanation!

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#354

Post by engineer_22 »

0-_-0 wrote: post #131
engineer_22 wrote: post #101

Earlier quoted context omitted.

> This design enables an especially compact motor architecture, high power and torque density, and new freedoms in drivetrain packaging. Hand waving.

No, it means the motor is smaller and it can be put into the wheel

Yeah that's exactly what the words say, thanks for parsing it for me.

No, it's hand waving because it doesn't explain how or why. That's what "hand waving" means.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#355

Post by BugsJustFindMe »

BugsJustFindMe wrote: post #350
engineer_22 wrote: post #111

I am speculating but here might be reasons axial flux motors have advantage over radial flux motors: 1) torque: torque = applied force x length of the lever. Because the radial flux rotor must fit inside the stator, therefore radius adjacent to the stator, therefore 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…

Think of the motor as a barrel and you can decide whether you put the magnets covering the barrel walls or covering the top and bottom, and your goal is to have the most magnet surface. At short barrel lengths, you get more magnet surface if you cover the top and bottom instead of the walls. 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 eq…

If you want a visual of how significant this size difference is, this image shows the sizes of the two motor types in relation to each other at equal strength because the axial motor no longer needs any of the barrel length: https://imgur.com/qwe3tuH

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#356

Post by klaff »

ed_balls wrote: post #228
klaff wrote: post #175

Earlier quoted context omitted.

It doesn't make that a good idea. Armature losses are proportional to torque squared - doesn't matter if it is radial or axial design. That's why all the EVs today have gear boxes with ratios like 13:1. Get rid of that gearbox and the steady-state losses go up with the square of that ratio. Then there are the issues of sprung mass, and where to put the mechanical brakes.

>gear boxes with ratios like 13:1. you add planetary gears >sprung mass you can integrate all into one hub (breaks, bearings, gears etc) and it weights pretty much the same. what you gain is more space for a bigger battery, torque vectoring, no loss on diff and CVs

> you can integrate all into one hub (breaks, bearings, gears etc) and it weights pretty much the same.

You would get to delete about half the mass of the half-shaft but otherwise you are cramming a lot of stuff into the wheel volume and it all has to survive living out there. Now your HV wiring and any cooling connections to the motor have to flex with the movements of the suspension and probably need guarding against rocks and other road debris. I think all EVs now have the drive electronics tightly coupled to the motors - now that either has to be separated or made compact enough to fit and rugged enough to survive a much higher vibration regime. We do have small amounts of electronics on hub assemblies today (I'm thinking of electronic parking brakes) so there is some precedent but that circuitry is much less challenging than an inverter handling 100s of kW.

>no loss on diff

I doubt there's much loss from differentials in EVs. They don't have the bevel gear of diffs used in longitudinal layout ICE vehicles and mostly the gears in a diff don't move relative to one another (unless you are doing donuts!), so the whole cage mostly acts like a solid gear giving whatever final ratio.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#357

Post by klaff »

zardo wrote: post #237
klaff wrote: post #175

Earlier quoted context omitted.

It doesn't make that a good idea. Armature losses are proportional to torque squared - doesn't matter if it is radial or axial design. That's why all the EVs today have gear boxes with ratios like 13:1. Get rid of that gearbox and the steady-state losses go up with the square of that ratio. Then there are the issues of sprung mass, and where to put the mechanical brakes.

YASA claims their integrated brake/wheel motor is lighter than comparable (supercar) disc brake systems.

Do they claim enough reliability and peak power capability to delete the mechanical brakes? I know Brembo is working on electric brakes that would eliminate the hydraulic circuits and pistons. I don't know what they plan to do to make sure the electrical side is as robust as the split-diagonal brake system we've been using for 60 years or so.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#358

Post by Mashimo »

SoftTalker wrote: post #334
Mashimo wrote: post #290

Earlier quoted context omitted.

With mandatory breaks you have to take while trucking in a lot of countries, is it really that far out? I would imagine you could charge while you sleep.

I don't think we have the battery power density to power an 80,000 lb (~36,200 kg) truck at 65mph for 11 hours as allowed by the DOT Hours of Service Rules and Regulations (though I believe a 30 minute break is required after 8 hours, and the 11 hours of driving has to be within a 14 hour window, so some recharging stops may still work within those limits).

In most EU countries you have to take a break after 4.5 hours for about 45 minutes. And you can only drive 9h per day.

Sounds feasible to me.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#359

Post by zardo »

klaff wrote: post #357
zardo wrote: post #237

Earlier quoted context omitted.

YASA claims their integrated brake/wheel motor is lighter than comparable (supercar) disc brake systems.

Do they claim enough reliability and peak power capability to delete the mechanical brakes? I know Brembo is working on electric brakes that would eliminate the hydraulic circuits and pistons. I don't know what they plan to do to make sure the electrical side is as robust as the split-diagonal brake system we've been using for 60 years or so.

Having four wheel motors solves any issues that compromise a single unit, but I don't think they've answered how they would mitigate potential system issues that might bring them all down at once.

Re: Mercedes‑Benz starts large‑scale production of electric axial flux motor

#360

Post by xethos »

dotancohen wrote: post #344
xethos wrote: post #302

Earlier quoted context omitted.

As efficiency improves across motors and inverters, wouldn't regen make CoD matter more, possibly tilting it to the dominant factor again?

Regen recoups about 80% of the kinetic energy, and it is already up close to the theoretical physical limit without switching to exotic materials. Cd will never be the dominating factor at speeds which do not produce significant aerodynamic drag.

> Cd will never be the dominating factor at speeds which do not produce significant aerodynamic drag

That helped it sink in, thank you

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