About YASA technology

R

Roookee

1 mW
Joined
Aug 19, 2024
Messages
16
Location
Europe
Hi Everybody,
Probably a rookie question: I wonder why I could not find DIY YASA Motors.

At first glance, making the coils or making the rotors with appropriate metal disc seem to be the easiest motor typology for DIY candidate
That is why I have this question

Now, regarding the IP (Intellectual Property/ Patents), I have been told that as long as you do not undertake production/commercialization, there is no infrigement of patent if DIY for private use. But of course I am not a lawyer.

Thanks in adance and Merry Xmas
R
 
Probably the same reason no one diy builds any motor for everyday use, off the shelf cant be beat for reliability and minimum down time if failure strikes.. But if skilled and keen go for it. Singular emulation is high praise, not ripping off.. start duplication however and look forward to meeting lawyers.
 
fill said:
no one diy builds any motor for everyday use,
Click to expand...
While most of the ones I've seen here on ES were done for experimental purposes, you might check out some of the threads on ES about DIY motors that were built for (and used for) "everyday use", such as Lebowski's and APLs (there's others I don't recall names of).
 
amberwolf said:
While most of the ones I've seen here on ES were done for experimental purposes, you might check out some of the threads on ES about DIY motors that were built for (and used for) "everyday use", such as Lebowski's and APLs (there's others I don't recall names of).
Click to expand...
Consider me corrected. FEW things are indeed absolute.
 
I've been involved in 2 commercial axial flux motors so far. They're well trodden ground and the ip is generally dubious, lawyers will let anything get patents because they get money arguing the toss later.

The difficulty is almost entirely mechanical and it is really hard. You need huge magnets barely 1mm from steel and that's a hell of a force to take. Radial motors have the benefit of rotational symmetry so the high forces cancel... Axial motors do not.
 
Last edited:
Thanks for your replies,

Actually I discovered ES after Googlelizing "AFPM DIY", it lead me to APL's thread first and then to HallBachHereo's project.

SpinningMagnets'project to "blueprint" a 2Kw motor for e-mobility has a lot of appeal to me, as according to very basic calculations for my project, I need around 1.8Kw at the wheel to climb a 15% slope (road) at around 25km/h (legal speed limit) for a total weight around 100kg, so a bit more than 2Kw nominal power, depend on the efficiency.

If I mentionned the YASA technology, while I would dream of a TORUS with Hallbach/Litz wire/... it is because I did not see any DIY TORUS as light as it should be according to the theory, and it seems that 3D printing parts are not stiff enough.... I just guess

That is why I suspect TORUS DIY is much more difficult than it look at first glance, I guessed it could be easier with YASA for similar performance, regardless of IP issues.

When it comes to motor's weight:

LaunchPoint company which makes small AFPM TORUS like a mini CSIRO AURORA motor, has presented a kind of Abacus with RPM on the horizontal axis and motor power ratio (Kw/Kg of motor mass) for the vertical axis, and this chart at constant power and constant efficiency shows that a 1Kw TORUS motor at 1000rpm will weight something like 0.8 horsepower/pound while a 1Kw at 6000rpm would be around 6-7hp/lb.

So far, the existing alternative easy to purchase is an outrunner at very low Kv as described on this link, no idea regarding the efficiency and its weigh is not that light.

But buying on line is not as exciting as DIY, otherwise ES would not exist.

Cheers

R
 
Thanks for these practical infos regarding AFPM, I remember Aurora CSIRO motor report explaining the very strong attraction between the 2 rotors being an issue.
As a result I wonder how the magnets can stay in place and to which extend epoxy glue will address the issue ?
There is so much info on ES that I probably have to dig much more, but I am a bit intimidated by all the people here who obviously have engineer background which is not my case.
Cheers
R
 
Those LaunchPoint axial motors are the sort of minimalist hi performance stuff I find appealing. Probably DoD unobtanium, and AFAIK good axial tech hasn't really trickled down to us lowly ebikers yet.

Their 8" 6kw unit is intriguing. I didn't see any detailed specs attached. Any guesses guys as to whether that's a PCB stator? Methinks yes... They used a fairly obvious tapered ribbed rotor design to avoid deflection with apparently the magnets glued in from the back.

Does anyone here have experience with PCB stators? The Infinitum and ECM startups claim they're adequately powerful. I'm considering an axial build but am early in the info gathering.
 
Barncat said:
Those LaunchPoint axial motors are the sort of minimalist hi performance stuff I find appealing. Probably DoD unobtanium, and AFAIK good axial tech hasn't really trickled down to us lowly ebikers yet.
Click to expand...
Not unless you make it yourself. ;) (like APL did, for instance)
 
Right. I believe only Lebowski and APL have built roadworthy mid drive axials.

I might forsake my mid drives for a custom rear hub if I can get the motor/rear wheel under 7 lbs or so. The crux would be a low kv PCB stator capable of 12-15kw roughly 9-11" diameter. I have no interest in winding copper. They say these stators have very low cogging torque- perfect for regen and eliminating sprockets and chain.
 
Thanks for your posts Barncat, I don't feel lonely anymore with this idea.
this 8''/6Kw you mentionned, AFAIR weights barely more than 1 pound, but not sure, it was used as a starter for IC engine on UAV, in order to be able to stop and restart the IC engine during operation. Last time I visited Launchpoint website, I did find what I have seen a few year ago.
I remember they mentionned carbon fiber disk for the rotor, which can be helpfull to adress stifness issue.

As long as you have the magnets and the Litz wire it lookS to me very simple because I am very rookie,
But if MARAND sellS copycat of Aurora motor for 100 000 bucks , even if it is AUD it is not cheap and not far from the price of a Tesla..
so one can imagine it is not that simple.
Cheers and happy week end
R
 
Thanks for pointing out LaunchPoint Roookee. I was unfamiliar. It does look like Defense Dept stuff.

In theory, one could build a lightweight high performance axial layout spokeless rear hub motor integrated with a 20" alloy rim. I find heavy duty 20 x 2.4 bike tires to be perfectly adequate for high speed street use, and they require less gear reduction (or Kv reduction) than a larger diameter wheel.

Painting with a broad brush: 2 carbon/foam/carbon disc rotors bolted to alloy press fit spacers riding on quality radial axle bearings, sandwiching a powerful PCB stator affixed to a hollow oversized aluminum axle with phase wires conventionally routed through same. Rotors would attach directly to rim, with flat Halbach array magnets epoxied to their inner faces, possibly with perimeter aluminum spacers just outside the stator diameter to hold a perfect 1mm or less air gap on already very stiff light material. I have not fully planned assembly sequence and materials interfaces, yet. Fairly straightforward design but tricky details...

However I don't know if you can push 15kw (bursts) through, say, a 12 inch diameter PCB stator, I have no experience designing one, or know what they cost. Anyone here have some background in this relatively new application of that tech?
 
Last edited:
Barncat,
Please find attached a graph I downloaded years ago from Launchpoint website. From this, I understood:
The higher the RPM, the smaller and the cheapest the motor, as TORUS has around 70% of its weight made of hight performance magnets and copper.

That is what made me understand why hub motors with low RPM are a bit heavy for their power.

Regarding your 15Kw project, while I cannot be very helpfull for the conception, I think this idea is very interesting because in Europe, there is a new category of tiny car called "Quadricycles" and the regulatory framework for this new category included a max lenght a max width a max weight and a max continuous power at 15Kw.

That said, the Lucidmotors concept which put the differential inside the rotor and then a 6/1 ratio planetary gear on each side for each wheel is very interesting from a cost point of view as it is like an arbitrage between motor weigh/cost and planetary gear cost.

Furthermore as the differential is turning at high speed/low torque it can be very small compared to a differential which would transmit the torque directly to the wheels. A very smart package IMHO.

In conclusion, I would not be surprised if somedays a Chinese or Indian company bring this kind of product to the market, but a 15Kw DIY project is a little bit beyond my skills especially doing it alone in my "Outback".

Thanks for posting your projects
Cheers
R
 

Attachments

  • LaunchPoint TORUS Graph.png
    LaunchPoint TORUS Graph.png
    12.1 KB · Views: 5
Appreciate the graph, your data and observations. Clearly then this motor topography is least suited to a direct drive hub motor operating in the max 1000rpm range, which is the ballpark for a 20" nominal tire. Oh well...
Planetary gears etc aren't a good DIY approach. Plus various disc parts would need to be laser or water jet cut for accuracy, and a special H section rim would be needed. This puts any proposed motor design back in the high RPM mid/chain drive category.
 
This graph made me understand why the first Tesla had a 12 000 rpm engine, now the Tesla engines are arouund 19 000/20 000 rpm
and some Chinese automakers have claimed a 27 500 rpm.
With mid chaine drive, you lose a few % of efficiency, but the weight and money you save with a high rpm motor can be invested in extra batteries, so thorough calculations must be made, involving the whole package for relevant comparisons.
Cheers
R
 
Yes, I've documented 5 custom mid/chain drive builds here. I've never even considered conventional hub motors previously since any with adequate power weigh over 25 lbs. Unacceptable.

To clarify- do you know if those LaunchPoint motors use PCB stators? I only guessed they are and that may be wrong.

Some other info I found suggests printed stators could still be in the running, but they're probably ungodly expensive.
 
Sorry for late reply Barncat,
Rebarding PCB Stator, I dont think so, AFAIR it was a toroidal winding just like a smaller CSIRO Torus.
I just find a workpaper addressing an AFPM prototype with great disclosure regarding the material used, and interesting Magnets set-up including both Hallbach & segmented.
Don't blame me if reading it, you feel it is a like an homework assignment
Cheers
R
 

Attachments

  • AFPM YASA Workpaper.pdf
    8.6 MB · Views: 5
Skimmed through the research paper, thanks. Yes, Halbach arrays are known to produce better torque. I noticed too the authors data on electromagnetic deformation of the rotors- which is the difficult crux of axial design with such tight air gaps...

Trying to duplicate an actual YASA motor is beyond the scope of anything I'd personally tangle with. The theoretical lightweight PCB stator hub motor idea I outlined above is not totally out of the question, but I'll need to do a LOT more thinking before any attempt is made.

I wish you well with any building efforts you may undertake.
 
You must log in or register to reply here.
Back
Top