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Jan 06, 2019, 04:13 AM
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Skylar's Avatar
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Cool

Halbach Array in Tesla Model 3 electric motor ?


Video showing the Halbach Array construction and insides of the motor

Edit:
Earlier versions of Tesla cars employed induction motors. At the time, I was wondering what Elon Musk's reasons for that would be, but it now seems he just followed the technology used by other EV manufacturers. Members of this forum could have advised him otherwise, but I doubt that he would have listened to us.

At last, Elon has broken away from the induction motor technology and are now using magnets in the Model 3 motor.

Further reading
Last edited by Skylar; Jan 11, 2019 at 02:11 AM. Reason: More content added
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Jan 06, 2019, 04:58 AM
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thank you for the link. Halbach is very tempting for modelers as well. I made some experiments last months and I'm very pleased with results.
Jan 06, 2019, 06:39 AM
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Hi,
Thats very attractive. Did u do the machine work? What style arrays did you work with. What kind of drive did you use? What about it pleased you?
Jan 06, 2019, 08:03 AM
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Originally Posted by adamd11pl
thank you for the link. Halbach is very tempting for modelers as well. I made some experiments last months and I'm very pleased with results.
Can we have more details and/or pictures please. That looks like part of a paraglider motor.
Jan 06, 2019, 08:17 AM
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yes, I did machine work. I build custom motors for some time. This is rotor of 24 tooth 28 pole motor with linear Halbach array. That mean I have radial and tangential magnets coming one by another.
This rotor comes from experimental version of my TMCR (
D3 MOTORS TMCR 2018 (3 min 55 sec)
)
I'm looking for motor with highest possible torque/mass factor. Original TMCR drive was optimized with FEMM software with very good result (single 155kV 1.5kW motor weight 340g)
With Halbach and new stator motor weight 300g with the same kv and Rm.
Experimental motor is only workbench tested at the moment. It will be in flight tested during coming year.
Jan 06, 2019, 08:28 AM
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on right you can see my current version of stator, on the left is experimental stator.
Jan 06, 2019, 08:32 AM
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and this is how it looks together.
I'm still learning how to build properly such motors. It's a lot of work and fun.
Jan 06, 2019, 11:30 AM
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Skylar's Avatar
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Thanks for the pictures and info. What is the diameter of the stator?
Jan 06, 2019, 11:54 AM
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Diametr of stator is 70.4 mm. It's to small for paraglider
Jan 06, 2019, 01:14 PM
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Quote:
Originally Posted by adamd11pl
and this is how it looks together.
I'm still learning how to build properly such motors. It's a lot of work and fun.
Welcome Adam,
Glad to have you here. Nice motor....and nice to have a fresh interesting motor thread. Youre doing beautiful work. Do a dedicated thread if you want. It would be followed with great interest. Many questions i have but dont want to hijack tesla halbach thread.
Last edited by 1boho; Jan 06, 2019 at 01:27 PM.
Jan 07, 2019, 04:45 AM
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Quote:
Originally Posted by Skylar
Video showing the Halbach Array construction and insides of the motor

Edit:
Earlier versions of Tesla cars employed induction motors. At the time, I was wondering what Elon Musk's reasons for that would be, but it now seems he just followed the technology used by other EV manufacturers. Members of this forum could have advised him otherwise, but I doubt that he would have listened to us.

At last, Elon has broken away from the induction motor technology and are now using magnets in the Model 3 motor.

Further reading

The man says "four magnets glued together", which would mean that it could be a Halbach array, OR they just have used four single magnets per pole instead of one big one to reduce the eddy currents in the magnets.
I never seen IPM motors with Halbach Array, so the latter would make more sense, but i might be wrong and the guy does tell it right.

Generally this sort of motor is called IPM (intreriour permanent magnet), which basically means the magnets are placed somewhere inside the rotor instead of surface mounted.
The good thing about those IPM motors is they can produce additional reluctance torque aside from magnetical troque, but it requres a special kind of controller to get this magic torque (-> FOC with additional field weakening current).
The other good thing about IPM is the magnets cannot fly off the rotor at high RPM's
Last edited by madin8; Jan 07, 2019 at 05:05 AM.
Jan 07, 2019, 09:53 AM
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Yeah the entire rotor just explodes if it was a highspeed application. The soft magnetic rotor laminations wont support that. They will expand and ruin the gap. IPM is certainly no win all for magnet retention. For magnet retention use an interference fit sleeve of inconel carbon fiber composite or titanium.

If Elon knows whats best he better not take too much advice from here.
Last edited by 1boho; Jan 07, 2019 at 10:12 AM.
Jan 07, 2019, 11:16 AM
Registered User
The big advantage of the halbach array is that rotor back iron is not essential for flux return.
So would it make sense to use it on an IPM rotor where the magnets are surrounded with steel?

here is a high resolution picture of the Model 3 rotor where the four sections per magnet pole can be seen:
Jan 07, 2019, 01:02 PM
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Yes we know but that looks like a single barrier ipm not a halbach. I dont know the orientation of the poles there. But it looks like a basic single barrier ipm like u said.
Jan 09, 2019, 12:37 AM
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The single barrier rotor designs such as these require a high level of know how. I reviewed my notes from Hendershot.

This Tesla rotor appears to be a v-poIe IPM which is synchronous pm motor and a switched reluctance machine together, so it to scavenges additional torque from reluctance. No Halbach is essential for the addition of this "magic" reluctance torque. The poles in these engines are comprised of several pieces strategically placed for proprietary effects . One reason for going with an IPM is it reduces the cost of manufacturing because it requires less RARE earth. Another is its obviously efficient and generates excellent torque.


Anyway
Here is a video collection of an academic person developing hobby sized Halbach motors and sharing some of his Halbach experiments. His motors are showing high efficiencies. His max ETA on his 10 kW machine is 94%

Halbach array motor (2 KW) (0 min 25 sec)


https://www.youtube.com/user/imanmamed1
Last edited by 1boho; Jan 09, 2019 at 04:32 AM.


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