The magnets wasted in making the array?
If it works out to 1.4x, then using a standard configuration is still a LOT better.
I thought the field increased by only about 1.3x.
The T is higher, but the frequency and surface area is lower. Given the magnet material used. Net loss? And not just of money?
I don't understand 'why' anyway.
A standard dual rotor has no 'core'.
I can not comprehend what a PMA rotor 'core' is. ("without stator and rotor cores")
Seems to me a lot is being implied to the statement "The-disc-type PM brushless machines without stator and rotor cores were first manufactured commercially in the late 1990s"
Did they place the magnets on AL?
More accurate, did they NOT place the magnets on iron?
If this is a tiny machine, then the magnet weight could go past weight savings of the AL.
And I don't believe weight is an issue, because some of my tiny stuff is very (relative to standard dual rotors) heavy and it does not cause any problem I can measure.
If this is a large machine, then the blades need support. AL has fatigue issues, meaning steel will be in there anyway.
I am not clear on if this is a dual rotor or single rotor with laminations.
A single rotor with laminations will have far more iron losses if T gets to large, and that machine will certainly be better with regular old school neos.
What problem are you expecting to avoid?
G-