axial flux motor question !!

Lebowski said:
still, in the FEMM simulations shown above the flux path closes through the axle, which I think is not correct.
I imagine in real life it will close through the neighbouring sets of magnets and the axle will be flux free...
Click to expand...
Relatively. That's why I said
Miles said:
You can work on linearised circumferential sections in 2D. I did them at: 1/6; 1/2 & 5/6 of the active area.
Click to expand...
Not really practical with round magnets, though.... Why use round magnets in a radial array????

fd,
For someone who wanted to avoid using a steel core for weight reasons, you're pretty cavalier in your use of it elsewhere :mrgreen:
 
round magnet because I did not find out any rectangular one 65x20x10 mm :?

as you know it's difficult to make torque without iron :mrgreen: , for me that will be for the rotors , and as I do the job myself ( I have lathe and milling machine ) I will left the mini as possible , stators will be +/- 5 kg each , including magnets , so it's not too bad :wink:

it cant be seen in FEMM , but rotors have large holes at the center for the two hollow shaft that drives the rotor blades


i found some flat magnet wire that will do the job ( hope so !! ) , litz is too expensive , and copper foil is way too expensive :shock:
 


with and without , iron behind the magnets , nothing else to say :mrgreen:

i am gonna use it , maybe more !!! lol
 
another little question, when you have like me 2 stators with 40 magnets each , my pole pairs is 20 or 40 :?:
 
Tank's :wink:

what would be for you guy's the best ( available ) alloy to use as coils core , in my design , that means , not as stator ( it will be non conductive at all ) , just as coils core :wink:
 
I am not sure to need a core, but to be able to fit the copper in the coils , i had to make them thicker , almost 18 mm :? , and at 18 mm the magnetic field decrease a lot it remains not more than +/0.4 T , it's not enough :?

so I thought to give the coil a core to help :idea: , or make an 2 stators version

200Nm at 720 rpm it's really an hard work :mrgreen:
 
fdracing said:
....and at 18 mm the magnetic field decrease a lot it remains not more than +/0.4 T , it's not enough :?
Click to expand...
As we said before, you really need to do an FEA in the circumferential plane, to properly gauge the likely flux density. There will be far more leakage between the poles than dispersion in the radial direction. If it was simulated in 3D, I think you'd find it would probably be less than 0.4T.
 
I did it this afternoon, and the result is the same , betwen 0.45/0.55 T , magnets space is 7.5 mm on the top row and 1 mm at the 3rd row ( i have 3 row of magnets ), at this row the leakage is important , field doesnt exceed 0.4 T :?

and this having reduce my coil to 17 mm , and 0.5 mm air gap :?

I wish i could simulate it in 3d , like you i think it will be lower :(

the fact is that over 12 mm of total gap ( air + coil ) it doesnt work propely , the flux is minimum 0.55 /0.65 T , and I dont think that below 0.55 T an motor will realy give good numbers :roll:


axial flux motor will have more than 1 stators to make my numbers , let's start some new calculation and design with 2 stators / 3 rotors first ......
 
need your help one more time :oops:

data are as follow :

3 phases

96 volts

30 coils / 40 poles

one pole magnet is : 62 mm x 20 mm , 10 mm tick , N42 , back iron 10 mm

1 coils is : 5.4 m , 36 turns , copper foils 10x0.2 mm , coil surface 2114 mm2 , coil hole center surface 541 mm2

phase resistance 0.00456 ohms

Delta connected coils

magnets average radius : 155 mm

average Tesla in airgap : 0.65 T

calculated Kt : 1.2 Nm/A

what would be my Kv , efficiency and rated torque :?:

Tank you in advance for those who like to answer :wink:
 
Kt = 1/Kv I make that 7.958 rpm/V

With no iron losses, efficiency depends on the resistance losses in the
copper plus eddy current losses.

Rated torque depends on your cooling system.... :p
 
when I say phase resistance , for me it means phase to phase , 1 coil is 0.0456 ohms , so 10 parallele coils will be 0.00456 ohms , for me delta mean 10 parrallele coils connected from one phase to another phase and so on :wink:

i dont understand that 2/3 :?:
 
images


The phase resistance is the resistance of a single phase. Otherwise, things get very confusing........

For Wye (Star) termination, the phase to phase resistance is twice the phase resistance.

For Delta termination, the phase to phase resistance is 2/3 of the phase resistance.
 
ok , I got it .........once again :wink:

so in my case , phase to phase my resistance is 0.00304 ohms , pretty low !!
 
fdracing said:
need your help one more time :oops:


Delta connected coils



Tank you in advance for those who like to answer :wink:
Click to expand...

never connect in delta ! gives you unneccessary losses

http://endless-sphere.com/forums/viewtopic.php?f=30&t=45326&p=660660#p660660
 
the motor project I have for reference for my build have the coils group connected in parallele and it seams to works fine , what's the difference :?:

and why not delta :?:
 
fdracing said:
the motor project I have for reference for my build have the coils group connected in parallele and it seams to works fine , what's the difference :?:
Click to expand...
Perhaps you should have started this thread by sharing the reference :wink:

Lower voltage, higher current.
 
fdracing said:
the motor project I have for reference for my build have the coils group connected in parallele and it seams to works fine , what's the difference :?:

and why not delta :?:
Click to expand...

working fine and good efficiency are not the same.

why not delta, follow the link !
 
Miles said:
fdracing said:
the motor project I have for reference for my build have the coils group connected in parallele and it seams to works fine , what's the difference :?:
Click to expand...
Perhaps you should have started this thread by sharing the reference :wink:

Lower voltage, higher current.
Click to expand...

you are right :wink: , the "reference" is from "amasing diy projects" , i think you know this guy here
 
not the first choice for him and for you and probably many others :wink:

does it means impossible :?:

we'll see :wink:

people thougth the earth was plate before they discover it sphere .....
 
what effect or importance has the coil inner hole shape and surface :?: , and what if I fill it with hyperco laminated sheets :?:
 
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