Magnax - 98% peak efficient 16kg 200kw peak yokeless axial flux motor

This is nuts. Very similar to the emrax. One of the biggest differences seems to be that it spins twice as fast.

https://insideevs.com/news/361185/magnax-axial-flux-electric-motor/

Interesting looking motor but this caused me to pause:



I know iron losses are significant and well worth minimising but this chart seems to show very large variations in total motor efficiency. If the Magnax motor is 98% efficient (as claimed) then the chart implies an induction motor will be 20% less efficient *due to core losses alone*. Add in the additional copper, friction and windage losses and the induction motor is going to be well under 78% peak efficiency*?!

*Roughly. They're talking about efficiency at typical EV operating points to affect the vehicle range, but we only have peak efficiency numbers to compare, but they're likely closely correlated.

Am I missing something?

what you're missing is that it's yokeless because the yokes on you.


Analysis of the Yokeless and Segmented Armature machine.

A totally STUPID and mis-scaled graph, with no axes to add insult to injury.

Dumb press release too there are already multiple axial flux motors claiming very high efficiency and high output on the market.

Am I missing something?

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I don't think so. The only thing I can think of is that efficiency advantages probably has more to do with power density then range. Since power is related to how much heat the motor can shed. So, ignoring other factors, If a motor type 'X' has a efficiency of 92% and peak output of 10kw, then a 98% efficient motor of same size and weight would theoretically be able to handle 40kw.

Of course that doesn't get you anything if packaging constraints are not a issue and the 98% efficient motor costs more then 4 times as much. This would probably be a big deal in a small plane, but much less of a big deal in a small car.

And I am also aware of the hype-ness of the video. I'll believe their claims when I see actual motors doing actual work.

Other magnax threads:

https://endless-sphere.com/forums/search.php?keywords=magnax&terms=all&author=&sc=1&sf=all&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

There's some highly questionable claims in their materials for sure. A dyno graph will tell the truth; i just thought it was interesting that the emrax style axial flux motor could even be improved on at all, and thought i'd pass the word on :thumb:

Shame they don't make these kinds of motors in smaller sizes. An axial flux geared motor or mid drive would probably be the holy grail of ebiking. I do believe there is at least one DIY axial flux motor build going on on this forum.

neptronix said:

An axial flux geared motor or mid drive

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Yeah it would be badass and I would buy it immediately but on the other hand it's a fairly marginal improvement from something like astro the major issue is still the reduction. Where are the good, compact reduction units?? You can't even buy a Tangent now cuz they've decided theirs sucks and needs reengineering.

Where are the good, compact reduction units??

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Hiding inside of geared hub motors as dual stage planetary reduction gearsets. Kinda sucks when you have fantastically efficient, lightweight, and powerful motor only to double the price and lose all your efficiency gains through a transmission.

Single stage reduction by sprocket-and-chain is pretty dope though. Left hand chain for the win.

That's bad news about the Tangent.

flat tire said:

Yeah it would be badass and I would buy it immediately but on the other hand it's a fairly marginal improvement from something like astro the major issue is still the reduction. Where are the good, compact reduction units?? You can't even buy a Tangent now cuz they've decided theirs sucks and needs reengineering.

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It seemed like an amazing idea at the time, until i heard the sound that the transmission makes, even under a sine drive..
At least they are trying to re-engineer it instead of continue to push a mechanically dicey drive, unlike some companies which will remain unnamed..

I think the best weight/power ratio drive system we have today is the CYC X1 Pro, yet people on this forum have barely touched it so far . And there is also the astro drive, which is a super nice kit, but comes at double the price.

sleepy_tired said:

Hiding inside of geared hub motors as dual stage planetary reduction gearsets. Kinda sucks when you have fantastically efficient, lightweight, and powerful motor only to double the price and lose all your efficiency gains through a transmission.

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Yup, the dual reduction hubs have turned out to be not as fantastic as thought. I don't think that we can entirely blame the gears. Last year, MAC put razor thin 0.27mm laminations in their single stage motors, which only added maybe 1-2% extra efficiency, but they found and improvement and implemented it anyway, out of interest in making the best geared motors on the market, even if it raised the cost of the motor an entire, gasp, 20 dollars.

AFAIK Bafang, as usual, not exactly reaching for excellence, put 0.35mm lams in their dual reduction motors, as well as other manufacturers like Xiongda, etc. These dual reduction motors could greatly benefit from smaller lams, but again they drop the ball.

The CYC X1 hits the venn diagram in the center of these factors:
Cost ( OK - it's a little expensive at $~800, but the bang for the buck is good )
Efficiency ( Drive efficiency is likely >85% with such an efficient motor, despite the dual reductions )
Power Density ( It contains what is basically a poor man's astro motor and the drive comes in at something like 10lbs? )
Ease of Installation ( It's a mid drive; you could also rig it up to drive the back wheel directly and have a something that's nearly as powerful as a bigass QS motor )

What i think would be the ultimate drive for our ebikes would be a CSIRO pancake motor in a hub wheel, but i hear those things cost tens of thousands of dollars :lol:



https://renew.org.au/wp-content/uploads/2018/12/marand_high_efficiency_motor.pdf

neptronix said:

I think the best weight/power ratio drive system we have today is the CYC X1 Pro, yet people on this forum have barely touched it so far . And there is also the astro drive, which is a super nice kit, but comes at double the price.

Click to expand...

OK I just bought a CYC X1 pro. Can't wait to try it. Did you mean anything specific by Astro drive? I'd like that one too.

What i think would be the ultimate drive for our ebikes would be a CSIRO pancake motor in a hub wheel, but i hear those things cost tens of thousands of dollars :lol:

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Absolutely. The wheel itself would be the hub motor. It would end up looking something like those Zipp disc wheels. if you manage to put the magnets and windings at the edge of the wheel instead towards the center of it they could probably be very small since there would be so many of them.

The speed at which the magnets would move over the surface of the windings would be very high compared to conventional direct drive so the power would be very high for the mass. Almost as fast as those little direct drive hub motors they are using on electric skateboards nowadays. Sort of like using a small RC motor and friction drive, but with a hell of a lot more winding and magnets.

It's a 40 pole motor, so it doesn't seem like it would be a total nightmare to drive. At 1000rpm, you are only looking at 40,000 electrical RPM. An average ebike controller with something like a 16khz drive could manage 50,000 eRPM.

Sounds like torque central to me. Most DD hubs only have 26ish poles..

I'm a bit puzzled about something.
If I understand correctly, yokeless means that there is no back iron, it's basically a coil that goes from a magnet, to another magnet on the other side.

My question is, how do they attach this coil to the stator? I suppose it must be attached very firmly in order to withstand the forces, but I can't see how it's attached from any picture I've seen yet.