ES DIY Motor Challenge

Electric Motors and Controllers
markobetti   10 kW

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Re: ES DIY Motor Challenge

Post by markobetti » Jan 13 2016 2:16pm

Hi Miles,

Ugh , havent been here for long time...but i missed ES.
Ill apply for challenge with a friend from Croatia : 2,4kg motor needs to output 8.25 Nm :)
Motor we are making should be less OR EQUAL TO 2.5kg with i hope 8,25Nm
Any power limit ?
Anyway we started to work on this motor 3 months ago .
Does this in any way bends the rules or is it okay to apply ? :)

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Miles   100 GW

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Re: ES DIY Motor Challenge

Post by Miles » Jan 13 2016 2:39pm

Hi Marko,

I had to remind myself of the rules :)

Nm/kg to exceed 0.1 * mass (kg) + 3

So, for 2.4kg:

3.24 Nm/kg * 2.4 = 7.78 Nm

Too easy :mrgreen:

jacobbloy   100 W

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Re: ES DIY Motor Challenge

Post by jacobbloy » Feb 06 2016 6:48am

I'm just wondering if some one here can help! Iv been working on small hub motors for a skate board, I dont want to just go an offe the shelf convention, I have recently changed for 14pole to 24n28pole but my winding seems to be off.

I have wound it in a Wye configuration it seems to not be 120deg

These are my test results.
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goa604   1 mW

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Re: ES DIY Motor Challenge

Post by goa604 » Feb 12 2016 2:12am


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CobraJet   1 W

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Re: ES DIY Motor Challenge

Post by CobraJet » Feb 12 2016 8:35am

Thanks for sharing this link, that is awesome!

Ianhill   100 kW

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 03 2016 7:34pm

Hi all
Ive been thinking of building my own motor, I have not built one before but after a bit of research the design I feel suits my needs is a PMAsynRM or a permanent magnet assisted synchronous reluctance motor I believe these motors will run on a sensored controller ? The build would utilise samaruim magnets in the rotor and high temp winding wire so it would be more temperature resistant when pushed hard than ferrite, it would be a 12n8p configuration and be built to handle 10kw continuously.
Any tips or web pages with juicey info would be much appreciated.

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Lebowski   1 GW

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Re: ES DIY Motor Challenge

Post by Lebowski » Nov 04 2016 3:15am

Ianhill wrote:Hi all
Ive been thinking of building my own motor, I have not built one before but after a bit of research the design I feel suits my needs is a PMAsynRM or a permanent magnet assisted synchronous reluctance motor I believe these motors will run on a sensored controller ? The build would utilise samaruim magnets in the rotor and high temp winding wire so it would be more temperature resistant when pushed hard than ferrite, it would be a 12n8p configuration and be built to handle 10kw continuously.
Any tips or web pages with juicey info would be much appreciated.
I would not run a standard sensored controller with a Reluctance Motor, the phase info needs to be twice as accurate as for a normal PM motor.

Why do you think a Reluctance Motor is best ? Because you expect high temperatures ? What kind of maximum/minimum inductance ratio are you aiming for ?

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 04 2016 12:30pm

I'm not sure really as regards to max min inductance,I would properly go for a bldc if the pmsynrm can't be run.
I wanted it to be robust, the reason I went for the relectamce motor was cost but if i need a new controller then that argument is beat and the bldc would be cheaper still at the weighing in stage at moment.

Ianhill   100 kW

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 04 2016 10:27pm

In my mind I still think it will work, not a normal reluctance but a magnetic one so its synchronous just like a bldc so the rotors will turn no differently just different forces going on, but this were i come unstuck will a variable frequency drive control the throttle, is it just the relationships between the rotor/stator differ and a motor designed around 120/60° deg rotor movement per cycle work fine ???
So what I thought was the lower flux power of samarium could be overcome with added flux from a reluctance rotor giving an effective boost to power within a small motor plus it could handle high heat but being none induction there won't be much heat generated meaning large power throughput in short cycles.
Anyone with better knowledge care to shut me up ???

After lots of double checking it will work on a sensored controller the correct design mind but it has to be the synchronous type switched reluctances motors require a specialized controller for the job like mentioned.

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 05 2016 8:47pm

Looks like the rotor design im thinking of is in a very similar form in the 2016 Chevy volt, But a 12n8p config of this type of motor has design patients own by a German company that have susccesfully won court battles over other firms trying to produce it.
Its basically a 12n8p perm mag and reluctance.
Fig1.jpg
After watching different induction cars launch, Perm mag cars launch much harder off the line than an induction motor simply can not get the torque off the line even if it goes on to out rev the perm so perm reluctance will be key for kick ass off the lights torque and massive top end if the rotor is a high speed design.

ecotech   10 mW

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Re: ES DIY Motor Challenge

Post by ecotech » Nov 14 2016 3:54pm

How does this motor you say look like?

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 14 2016 5:38pm

ecotech wrote:How does this motor you say look like?
I've got two motors in the design stage, one is a perm reluctance, a miniature version of the Chevy volt unit, The second motor is an bldc outrunner design ive come up with an idea to utilize scrap components that anyone can build.
Its in a design phase, its difficult finding suitable materials to make the stator laminate. While having the missus going yang yang yang in my ear.

ecotech   10 mW

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Re: ES DIY Motor Challenge

Post by ecotech » Nov 16 2016 8:51am

I find it easier to not use any iron at all but what happens is the case of the motor must have small magnetic coercivity otherwise the flux goes in the case instead of the copper wire.

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 18 2016 4:36am

I can not understand why one would not want to use iron in a motor around the coils it amplify's the magnetic field, the only time I've seen a ironless core is in a axial generator where the magnets are spinning and the field lines are directly across the coils interacting with the copper so iron is not used because it introduces eddy losses, but in a motor where we want to create an electro magnet iron is key and making it withstand higher frequency's will give a more efficient design.

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Lebowski   1 GW

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Re: ES DIY Motor Challenge

Post by Lebowski » Nov 18 2016 5:05am

I always had a slightly different view. Iron does not amplify the magnetic field. It concentrates it in a smaller area, thus reducing the length of wire (resistance !) necessary to make N windings. But the field through the windings comes from the permanent magnets.

I've often wondered whether small area windings would be possible in a core-less design, but with the field concentrated by some sort of lens type focussing...

Also, motors and generators are the same thing, with the same design considerations. Whether a machine acts as a motor or a generator is purely and alone determined by the electronics attached to it. If the electronics suck power out it is a generator, if electronics shove power in it is a motor. Efficiency for both setups is ruled by the same consideration: get as much back-emf as possible with the least amount of winding resistance.

Have you seen my motor building threads ? (look for Lebowski axial flux and triple stator axial flux)

Ianhill   100 kW

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Re: ES DIY Motor Challenge

Post by Ianhill » Nov 18 2016 7:26am

Lebowski wrote:I always had a slightly different view. Iron does not amplify the magnetic field. It concentrates it in a smaller area, thus reducing the length of wire (resistance !) necessary to make N windings. But the field through the windings comes from the permanent magnets.

I've often wondered whether small area windings would be possible in a core-less design, but with the field concentrated by some sort of lens type focussing...

Also, motors and generators are the same thing, with the same design considerations. Whether a machine acts as a motor or a generator is purely and alone determined by the electronics attached to it. If the electronics suck power out it is a generator, if electronics shove power in it is a motor. Efficiency for both setups is ruled by the same consideration: get as much back-emf as possible with the least amount of winding resistance.

Have you seen my motor building threads ? (look for Lebowski axial flux and triple stator axial flux)
You schooled me by there.
Your correct the magnetic field is concentrated not amplified and the coreless motors is just another type of motor I've never encountered, I found this article backing up your info
http://www.designworldonline.com/ironle ... cond-look/
Thanks for the Input helps educate a monkey :lol:
I'll be sure to have a read of your threads.

ecotech   10 mW

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Re: ES DIY Motor Challenge

Post by ecotech » Nov 19 2016 7:25am

Ferromagnets concetrate the flux somewhere by the principle of superposition, infinetisimal current of loops in higher magnetic permeability materials cancel and amplify the resulted forces by the magnetic field in specific regions.

For bikes and bicycles how much torque and power is the optimal?

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amberwolf   100 GW

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Re: ES DIY Motor Challenge

Post by amberwolf » Nov 19 2016 4:45pm

Depends on what you're doing with it and in what terrain, how you're driving the wheel with the motor, etc (direct drive, geared hub, mult-gear middrive, etc).

For instance, you'd need way more torque and power for my cargo / dog hauler projects than a typical bicycle usage, even on the flat roads here; see the links for CrazyBike2 and SB Cruiser in my signature. If I had to do what I do in hillly areas, it'd take even more.

Chavis   1 µW

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Re: ES DIY Motor Challenge

Post by Chavis » Apr 26 2018 7:39pm

? Where did candidates go ? Did this die out?

katzda   1 µW

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Re: ES DIY Motor Challenge

Post by katzda » Jul 22 2018 5:18pm

I'm new to this forum. I just want to ask what do you think of my sketched design? I wish there was a compromise between geared and non geared hub motors. I later realized that the outer freewheel layer would have to go around closer to the axle to provide for disk brake compatibility.
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fechter   100 GW

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Re: ES DIY Motor Challenge

Post by fechter » Jul 22 2018 9:50pm

katzda wrote:
Jul 22 2018 5:18pm
I'm new to this forum. I just want to ask what do you think of my sketched design? I wish there was a compromise between geared and non geared hub motors. I later realized that the outer freewheel layer would have to go around closer to the axle to provide for disk brake compatibility.
For sure there is a lot of drag with a DD hub motor. Depending on hills and riding style, regen might sort of make up for it. If you want to pedal unassisted for any length of time, then it would be a definite advantage.

Not sure what would be the best way to do it. A freewheel mechanism like the drawing would add a lot of expense and some extra weight. Something similar to the setup in a geared hub but without the gears would probably be the easiest.

Another way would be to use an ironless motor or just better iron. Stuff like ferrite or Metglass would cut the drag way down as these practically eliminate eddy currents in the core. Also use very fine copper wire with many parallel strands to reduce eddy currents in the copper and improve high frequency performance. With better materials, you could have the same weight and simple reliable design.
"One test is worth a thousand opinions"

Ianhill   100 kW

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Re: ES DIY Motor Challenge

Post by Ianhill » Jul 22 2018 11:04pm

Fetcher is close to the point.

Adding the freewheel mech is going to introduce complexity and added weight, size etc.

There's a way around this by removing the stator tooth completely and lay the winding in epoxy directly on top of the iron between the magnet ring with its vector aligned to the magnets, and use the inductive coupling to the back iron to dictate the gap between the magnets and iron size vs the operational voltage and torque this will give the size of your total available copperfill and motor size.

What you will end up with is something that looks like a slotless motor that has no cogging forces at all and can still produce high torque without breaking freewheel pawls and will have less saturation of the iron so it's capable of high rpm if the magnet ring is built with gaps but you will lose initial torque due to being able to operate at high rpm without cooking the magnets.

I've been researching about slotless motors and how magnets suffer with eddy currents in my spare time so this is something I can see that could be improved. But you will lower torque output compared to the cogging version no doubt with like for like material content as the magnets have no gap's between eachother and are compacted tight, that's bad for eddy leakage between each magnet at increased rpm that's why magnets fry at high rpm if the ring ain't got eddy gaps or magnet segmentation the leakage increases with rpm but for stall torque it's going to give a increased torque figure.

But at the end of the day we measure a motor by its total output power so it's rpm handling is a big deal and that cogging torque is robbing the motor of its overall torque output as it has to be overcome before the motor will turn and throughout the full rotation it keeps happening with every phase pulse there's a cogging torque loss.

Lots of good reads and info at this site how commutation works lots of eye openers.

https://www.motioncontroltips.com/whats ... ss-motors/

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Re: ES DIY Motor Challenge

Post by katzda » Jul 25 2018 3:09pm

Love you guys :-) It really sounds amazing, although I don't understand half of it. :-) I with that someone with your knowledge could design it and pass it on to someone who could build it. I don't even know how to use CAD.

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Re: ES DIY Motor Challenge

Post by Ianhill » Jul 27 2018 2:34pm

I think most of us will have torque ripple on our motors for quiet some time yet without some new type of design as what I mentioned will use more rare earth and cost big time to produce the rotor for a prototype even with production run and cost savings in bulk it will still cost a good 1/2 more in production time and material increase, so I think when we see such a smooth motor it's design will need to be better on the pocket and less rare earth not more and there's people out there doing it but they have ties to businesses that will forbid them from giving us just a trickle of info.

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