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There are quite a lot of IPM inrunners, but I have never heard of an outrunner that is IPM. Why not? I admit that the motor bell would gain some weight in the process and maybe that's the main reason for not making IPM outrunners?
Outrunners (or outer-rotor motors) are typically used where the intent is to maximize the radius to the rotor-stator gap, realizing that the stator is much bulkier than a surface-magnet rotor; burying the magnets in a bulkier rotor would negate that advantage.

While the higher rotational inertia of the outrunner design is desirable (or at least tolerable) in some applications, making the rotor much more massive probably still isn't a good idea.

This can't be worse than the spinning mass of a hub motor!
Direct-drive in-wheel motors are another mess entirely, but I'll note that a direct-drive motor runs at only wheel speed, while a normal geared motor runs at a significant multiple of that speed, making rotational inertia much more important.

The mass of an IPM inrunner armature vs an SPM armature is probably pretty close to the same. There's no added spinning mass issues.
Sometimes it's about rotational inertia, not just mass, and rotational inertia is about the radius where the mass is located. If a IPM inrunner rotor and a SPM outrunner rotor have the same mass and the same radius (to the rotor-stator gap), the outrunner will have much higher rotational inertia because that mass is at a larger radius.

Most IPM inrunners have the magnets angled inwards in a V like this. Not all do, but this is very common. Does anyone know why?
If they were not angled in, they would just be at the surface, and would be surface permanent magnets. If you look at the flux paths at various speeds - not just the mathematical models of motor performance - you would probably find that the interior magnets in a vee configuration are suited to producing reluctance torque at higher speed, which is what the "MTPA" discussion appears to be about. Be prepared to look at a lot of diagrams in a lot of articles...
 

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Agreed hubs tend to suck. Good thing I never mentioned them other than as a bad example. LOL

The title of the web site is "electric cars", but there are plenty of people on here, myself included, not building cars or anything 4 wheeled. This web site is about EV's of any kind, not just cars despite the domain name.
OK. What are you building? What application is this for, to where an inrunner is suboptimal?

You agreed hub motors suck. You did not say you were building an airplane. What application did I miss? Nuclear submarine?

What's the end problem being solved, because you're creating many problems by playing with motor magnet configs like a 2 year old with a Lego set vs defining a specific problem being solved? Brian mentioned some of them.

Pancake motors solve a packaging problem. Period - they suck at just about everything else. This "lever" you speak of, presumably to produce higher torque, is crap, as it integrates magnetic forces over the radius and do not act on the rim of the motor.

The SPMs being held in that photo of yours are not "categorically IPM" - that configuration of SPM keeps the magnets from fragging/flying-off at high RPM and flat magnets are cheaper than arcs.

It's easy to fall in love, but love leads to doing dumb things.
 

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A pancake motor uses a flat armature to create a super thin mover, unlike the sloppy marketing use of the term in your toy R/C outrunner motors:


Go play with your pile of Lego blocks - nobody's stopping you from engaging in a pointless waste of time (are you a student or academic by any chance?). When you grow up, you'll learn the first step in finding a solution is to properly define (& constrain) the problem. At that point, amazing things can happen. Solutions looking for problems almost always fail.

What does the 2 year old come up with? 7 monkeys typing Shakespeare.
 

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No...you made unqualified assertions.

You were asked what application this was for. Still waiting for an answer.

You were also set loose to go play, but you clearly don't have the confidence to go down the rabbit hole alone and are super-worried about wasting your own time on this boondoggle vs wasting everyone's in a group hug. Group fail is acceptable for Gen Z.

Go look into it. Even us jerks have open minds to new discoveries.
 

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It seems that the slanted IPM magnets help focus and concentrate the flux of the poles; but being embedded they also increase the air gap distance which reduces the flux in the gap and the back emf voltage; and they rigidly and securly hold the magnets in the rotor for high speed rotation without concern for flinging magnets loose from glued-on surface mounting.

This is from the ford mach-e motor teardown video, there is a double row of internal magnets, so 4 magnets per pole

Automotive tire Bicycle part Rim Font Automotive design


end view of the 8-pole flux pattern

Photograph Black Organism Medical imaging Font


and on the rotor surface showing a step or skew in the laminations to reduce cogging torque

Product Automotive lighting Font Automotive design Aqua



the flux appears concentrated to correspond over about 6 slots/teeth per pole with 48 slots in the laminations.
Wound with some large gage flat profile wire with hairpin end turns

Tire Automotive tire Motor vehicle Automotive lighting Automotive design



Maybe for an outrunner the magnets would be slanted in the opposite slope such that the magnetic field would diverge to match the wider pole teeth of the outrunner stator. How many poles in your outrunner?
 

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Laminated steel is for normalizing losses, eddy flows and In some cases almost eliminating them. Also makes production easier and cheaper.

15krpm is ok when the motor weighs a couple ounces, but when it weighs a hundred pounds, operating forces start exceeding material strengths so you end up chasing weight increases or buying and attempting to machine exotic high strength materials which is possible but expensive. In tesla's case, their motor took a long while to get where they are today.
 
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