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Jan 16, 2019, 06:52 AM
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Originally Posted by NX-687
Say the IPM , is it very different to a model plane ESC
You probably can spin those IPM motors with most RC ESC's, because they have a similar BEMF as motors with surface mounted magnets. However the disadvantage would be that you cannot make use of the potential for the "magic" reluctance torque.
What it needs is a controller that features field oriented control with flux weakening and MTPA tracking (to get maximum torque per amp).
MTPA would mean a constant varying phase shift between d and q axis current over the entire RPM range (i believe this would be a bit similar as if you would constantly adjust the timing on an RC ESC).

Originally Posted by Christian Lucas
Hi 1boho,

yes , he is right . But he is not right that the magnets can not fly away at high rotor speed. Let this rotor rev at highest rpm and you will see that the soft iron will bend and break at a circumferential speed of mach 2. A outrunner with carbon bell and Halbach array inside will stand this speed and can run with narrow gap for highest magnetic flux.

Happy Amps Christian
Christian you should be fair and compare inrunner VS inrunner, and not inrunner VS outrunner
Last edited by madin8; Jan 16, 2019 at 08:27 AM.
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Jan 16, 2019, 07:31 AM
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No he doesn't because the TESLA IPM is not designed for high rpm and it would fail at high rpm just like you've been told in either configuration . High speed magnet retention comes by way of retention sleeves like you've already been told. Read the paper and understand that was the limit of the IPM design the balancing act between mechanical integrity for some semblance of retention and low iron loss. Its the bottle neck of the machine in itself.

Do not run an Adaptto ev drive in an rc model that's larger than all outdoors and less powerful than what's already available to us. The plugs alone are the size of servos..... APD, MGM, YGE all have a much higher power density than anything in their line. If you passed up YGE, MGM, SCHULZE, APD, ........ for this thing you wouldnt be all that impressed. I looked at the numbers sizes and weights and the only thing it is good for is an ebike . You don't put this thing in an rc model. Its not practical and any small efficiency gains will be eaten by it's inferior power density. Its too damn big for anything most of us do. Dewalt drill runs an IPM barrier type rotor and its driven by a BLDC drive. At it eons ago.

Can you post the information showing how field weakening increased torque. There is no magic in any of this.

You do not need FOC for field weakening and YGE and many other BLDC drives use a sinus commutation on the low end and switch to block commutation at WOT. When did Adaptto know rc drives better than Matthias Schulze, Castle Creations, MGM COMP PRO, APD,YGE all designed with us in mind by RC modelers. And when did you know more than electrical and electronic engineers like Christian and I? We know all that's needed for field weakening is a phase shift and even Graupner has that in their BLDC car drives....
Do you know that Christian and Andreas Lehner pioneered one of the first a brushless drives in RC? I have the photos of the drive if you need to see it. Its much easier to stay in the EV lane.
Last edited by 1boho; Jan 16, 2019 at 01:19 PM.
Jan 17, 2019, 02:40 AM
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Originally Posted by Ron van Sommeren
Wouldn't that make the magnetspacing in Adam's motor counterproductive?

Vriendelijke groeten Ron
Are you referring to the small spacings between the magnets (side by side) which look like less than 0,2-0,1mm? Or magnet coverage?

From what i know in a magnetic circuit any spacings or air gaps will add magnetic resistance which will lower the flux density somewhere, but i don't think you can do it much better as Adam did it
Gluing magnets can be a pita, especially if they reject from each other which will be the case if you have to glue a south pole magnet beside another one with the south pole on the same side (if you do magnet segmentation).
Last edited by madin8; Jan 17, 2019 at 02:47 AM.
Jan 17, 2019, 06:54 AM
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64x12 Halbach array dipole. Inside Diameter is 40mm outside is 64mm. Magnets are 48H . Array is 140.00 The array comes in a copper sleeve. You slow and aggressively hard tool turn with few passes or grind your thin bell in 2 1/2 inch id 304 stainless pipe close to final od/ id after the final operations you brush the glue on the id several mm from the end of the bell. You turn a soft mandrel that will slide easily inside the bell. You align this copper sleeve id with the bell id and gently press the array in place. The 304 is a better high speed alternative. If you are going to do a lightweight easily machinable slow rotating. DD plane drive perhaps you make the bell from T6 and use air coils. For a higher speed application the non magnetic work hardenable 304 stainless UTS and YS can be increased to very high values simply by making a high number of fine passes to the the finals.

@ Ron
To really know I would think that you would have to weigh the benefits of thermal resistors between the pm structures versus the benefits of continuity in the field. Especially in lower working temperature earth.
Last edited by 1boho; Jan 17, 2019 at 09:32 AM.
Feb 04, 2019, 11:27 AM
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It's possible the Tesla 3 magnets are segmented because they are different strengths. This could be done in an attempt to achieve more sinusoidal flux distribution in the air gap. A benefit of that would be reduced eddy current losses in the stator iron. An additional benefit would be reduced torque ripple, which would result in lower audible noise.

I don't think the purpose is to reduce eddy losses in the magnets themselves. This is more effectively done by segmenting them axially just like laminations, but the segmentation of this motor is azimuthal.

I acknowledge that the IPM motor format economizes certain costs, but I think the primary reason is to facilitate constant power over a large speed range thanks to efficient flux weakening capability. This property is very desirable in traction motors with single speed transmissions. I doubt this architecture is very useful for spinning props since they have a narrower speed range.

A standard RC controller should have the physical capability to efficiently drive an IPM motor, but it might not have the smarts to do so. A standard RC controller drives with a constant phase of about 90 electrical degrees from the back EMF. An IPM motor would run best with a phase difference that changes based on several variables. The Max Torque Per Amp (MTPA) algorithm mentioned above.
Apr 14, 2021, 04:36 PM
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Skylar's Avatar
Thread OP

More information about the Tesla Model 3 motor

This video shows that it is a hybrid induction / PM motor with most of the advantages of PM motors, but none of the drawbacks.

Tesla Model 3's motor - The Brilliant Engineering behind it (12 min 8 sec)
Apr 15, 2021, 01:01 AM
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Hi Christo,
yes , this motor is very good . The bad thing is that there is no esc that makes it possible to produce such motor for modelairplane.

Happy Amps Christian
Apr 15, 2021, 02:30 AM
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Skylar's Avatar
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Hi Christian

With so many companies now working on electric motor designs for automotive and full size aviation applications, it would be interesting to see in 10, 20 or even 50 years which type will be the clear winner and most used layout. I mean, many companies and universities are spending fortunes on just one layout, be it axial flux, radial flux, PM, induction or hybrids of these.


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