-
Howdy! we're looking for donations to finish custom knowledgebase software for this forum. Please see our Funding drive thread
Miles' 90mm inrunner build thread
- Thread starter Miles
- Start date
Thud
1 MW
It all looks lovely from here Miles.
& I am impressed with the quote form Laser laminations.
Thanks for that Farfle (that is 1/3rd of all of the quotes I gathered a year or so ago)
looking foward to seeing the progression.....could we have the 1st entry into the motor build challange?
& I am impressed with the quote form Laser laminations.
Thanks for that Farfle (that is 1/3rd of all of the quotes I gathered a year or so ago)
looking foward to seeing the progression.....could we have the 1st entry into the motor build challange?
Thud
1 MW
I actualy have done a little work on the axial flux design a couple weeks ago.
I spun a rough mold for the carbon fiber magnet rotors & flux ring to reside in...(yes i abandond the cast alloy ones already 8) ) I still need to seal it & make the membrane for vacume infusion of the 6" rotors.
baby steps....other projects seem to allways get slid in front of this one.
I spun a rough mold for the carbon fiber magnet rotors & flux ring to reside in...(yes i abandond the cast alloy ones already 8) ) I still need to seal it & make the membrane for vacume infusion of the 6" rotors.
baby steps....other projects seem to allways get slid in front of this one.
Farfle
100 kW
3.5nm from a motor that is barely 2 pounds. That's impressive...
crossbreak
1 MW
Nice to see the progress, miles. I'd also like to compare it with the tongxin. It is
4p 15t
51mm rotor dia
90mm outer dia stator, ~24mm thick, 0.5mm laminations
slip shaft dia: ~6.05mm
planets dia: ~34.60mm
calced ring dia: 75,25mm (maybe 75mm squeezed due friction drive)
reduction ratio (without slippage): 12.5:1
no-load rpm @ 37V: ~240rpm*12,5=3000
flux changing frequency @37 no load: 100Hz
calculated KV: ~80
stator weight: 756g
rotor weight: ~300g
should write this into the wiki...
shipping should be not too expensive, I can send it to you.
4p 15t
51mm rotor dia
90mm outer dia stator, ~24mm thick, 0.5mm laminations
slip shaft dia: ~6.05mm
planets dia: ~34.60mm
calced ring dia: 75,25mm (maybe 75mm squeezed due friction drive)
reduction ratio (without slippage): 12.5:1
no-load rpm @ 37V: ~240rpm*12,5=3000
flux changing frequency @37 no load: 100Hz
calculated KV: ~80
stator weight: 756g
rotor weight: ~300g
should write this into the wiki...
shipping should be not too expensive, I can send it to you.
Thanks crossbreak. That is an interesting comparison.
The way I see it is:
My rotor is 20% greater diameter.......
They have 4 poles, I have 16, so their Kt will be lower (for a given no. turns).
4 poles with 15 slots means that they have to use a fractional-slot winding - slightly greater end-turn losses.
4 poles need more material in the magnetic circuit - greater iron losses.
I have 400Hz flux frequency with 0.35mm lams, they have 100Hz with 0.5mm lams - They have less iron losses.
Losses on the magnetic circuit are probably comparable. Their losses on the electrical circuit will be much greater.
Anyone disagree?
The way I see it is:
My rotor is 20% greater diameter.......
They have 4 poles, I have 16, so their Kt will be lower (for a given no. turns).
4 poles with 15 slots means that they have to use a fractional-slot winding - slightly greater end-turn losses.
4 poles need more material in the magnetic circuit - greater iron losses.
I have 400Hz flux frequency with 0.35mm lams, they have 100Hz with 0.5mm lams - They have less iron losses.
Losses on the magnetic circuit are probably comparable. Their losses on the electrical circuit will be much greater.
Anyone disagree?
Hi Miles, I really like your little motor design nice and light for the Nm's. I have a question regarding the backing iron is it also laminated M19?
I am just trying to come to terms with the incredible heat that can be generated in the magnets and backing iron at very high rpm. Do you use high silicon type steels to have high magnetic permeability yet high electrical resistance for the backing iron/flux ring, or should you use lamination's instead to overcome these backing iron hysteresis losses? Do available magnets electrical resistance have a large effect on this heat generated? This question is more tilted towards overclocking motors and coming to terms with the heat generated.
I am out of my depth please use little words.
Zappy
I am just trying to come to terms with the incredible heat that can be generated in the magnets and backing iron at very high rpm. Do you use high silicon type steels to have high magnetic permeability yet high electrical resistance for the backing iron/flux ring, or should you use lamination's instead to overcome these backing iron hysteresis losses? Do available magnets electrical resistance have a large effect on this heat generated? This question is more tilted towards overclocking motors and coming to terms with the heat generated.
I am out of my depth please use little words.
Zappy
Hi zappy.
Thanks!
Yes, I'll be using M19 or M15 steel in 0,35mm sheets. This has a relatively high Silicon content.
Iron losses are related to the fundamental frequency of the motor, which is a product of the rpm and the number of magnet pole pairs.
You divide the nominal rpm by 60 to get rps and then multiply by the number of magnet pole pairs to get the fundamental frequency in Hz.
There are two causes for iron losses in the stator, hysteresis and eddy currents. Hysteresis losses go up near to directly proportionate to the fundamental frequency but eddy current losses go up as the square of the fundamental frequency. The laminating of the stator is for the amelioration of the eddy current losses - eddy current losses go up as the square of the lamination thickness.
The thinnest standard electrical steel available is 0.35mm and the maximum frequency that's usually recommended for this is 400Hz. So, if you want to run a motor faster than this, you need to think about thinner laminations or eddy current losses can build up.
Outrunners have an inherent advantage over inrunners in that the magnets take up less space than the windings, so the the turning moment (at the airgap) is greater. Using a high number of magnet poles, as I have done, means that less iron is needed in the stator yoke. This allows more room for copper keeping the same airgap radius or, preferably, increasing the airgap radius. A higher number of magnet poles increases the fundamental frequency, though, so beyond a certain point you need to move to thinner laminations which is more expensive, in materials and machining.
Is that clear?
Thanks!
Yes, I'll be using M19 or M15 steel in 0,35mm sheets. This has a relatively high Silicon content.
Iron losses are related to the fundamental frequency of the motor, which is a product of the rpm and the number of magnet pole pairs.
You divide the nominal rpm by 60 to get rps and then multiply by the number of magnet pole pairs to get the fundamental frequency in Hz.
There are two causes for iron losses in the stator, hysteresis and eddy currents. Hysteresis losses go up near to directly proportionate to the fundamental frequency but eddy current losses go up as the square of the fundamental frequency. The laminating of the stator is for the amelioration of the eddy current losses - eddy current losses go up as the square of the lamination thickness.
The thinnest standard electrical steel available is 0.35mm and the maximum frequency that's usually recommended for this is 400Hz. So, if you want to run a motor faster than this, you need to think about thinner laminations or eddy current losses can build up.
Outrunners have an inherent advantage over inrunners in that the magnets take up less space than the windings, so the the turning moment (at the airgap) is greater. Using a high number of magnet poles, as I have done, means that less iron is needed in the stator yoke. This allows more room for copper keeping the same airgap radius or, preferably, increasing the airgap radius. A higher number of magnet poles increases the fundamental frequency, though, so beyond a certain point you need to move to thinner laminations which is more expensive, in materials and machining.
Is that clear?
Sorry, just read your question more carefully 
As far as the rotor structure/magnet back iron, it's not subject to flux direction changes as it moves with the magnets. So, the losses there and in the magnets themselves aren't normally that great. I've used a laminated structure for my rotor because it's a convenient way of getting the machining done with the faceting and locators for the magnets. It's also good to make use of the material on the inside of the stator lamination blank. Sometimes the magnets themselves are laminated to reduce eddy current losses within them. I think it's also important that the magnets are electrically isolated from the back-iron.
As far as the rotor structure/magnet back iron, it's not subject to flux direction changes as it moves with the magnets. So, the losses there and in the magnets themselves aren't normally that great. I've used a laminated structure for my rotor because it's a convenient way of getting the machining done with the faceting and locators for the magnets. It's also good to make use of the material on the inside of the stator lamination blank. Sometimes the magnets themselves are laminated to reduce eddy current losses within them. I think it's also important that the magnets are electrically isolated from the back-iron.
Thanks Miles, I'm talking outrunner at 1400hz and the heat seems to be coming from the actual magnets then torque starts dropping and it quickly heats up the bell. So a laminated magnet would be stacked on top of each other i'm guessing insulated with epoxy(?) so instead of 1 magnet 3mm thick you would have 3 magnets 1mm thick on top each other for example. I'm guessing magnet thickness would also be a big factor. What about the electrical resistance of the actual particular magnet?
Thanks zappy
Thanks zappy
Farfle
100 kW
Miles said:Interesting.... thanks...liveforphysics said:
Black epoxy coating is only an extra 0.18 euros per magnet, too...
Where are you getting the mags from? I may do another motor in the next year.
1400Hz is quite high.. How thick are the stator laminations? Are you sure the heat is generated within the magnets? I've only seen magnets laminated circumferentially. I'm not sure there's much one can do about the electrical resistance of the magnet?
I found a couple of papers in my collection that deal with this subject.
I found a couple of papers in my collection that deal with this subject.
I think I've left more room than I needed to for the endturns .......... I think I should be able to increase the stator length from 30mm to 35mm. My outside case length is the fixed dimension. Maybe I should order a greater stack of laminations than I am likely to need and do some test winds to determine how much stator I can fit in. Then order the magnets.....
Farfle
100 kW
Big fins! None of those pansy little ridges! 
:lol:
:lol:Trackman417
10 kW
Subscribed!
Can't wait to see what you will do with this thing
Let's hope all goes well and good luck with the winding.
Don't forget about pictures either.
What are your plans for the motor?
Can't wait to see what you will do with this thing
Let's hope all goes well and good luck with the winding.
Don't forget about pictures either.
What are your plans for the motor?
