I need a reality check here.
I'm contemplating winding a synchronous motor.
24 pole, 36 slots. (not really important anyway)
(i'm looking at 19$ worth of magnets, chump change for the time invested.)
current estimate is .75 cubic inches of N48 magnet, but this could be doubled without much more work.
(surface mount 1 inch by 1/4th inch by 1/16th inch magnets, 24 poles)
The energy product of the magnets, N48 works out to 380 KJ/M^3
divide by 61,037 cubic inches per cubic meter and you get 6.2 joules of energy stored per cubic inch of magnet.
at 60 Hz there's 120 reversals per second, multiplying by .75 cubic inches of magnet and i get ~560 watts.
so neglecting the vector math, seems initially there is 56 watts per 10% of magnet demagnetization.
Or 74 watts per cubic inch per 10% magnet utilization at 60 hz.
does this fit reality?
known example 1:
toyota prius: 2.2 kilograms develop 80 hp. this works out to 18 cubic inches, or 3320 watts per cubic inch.
this is 45 times my 10% figure.
which means if they can run it at 45% demagnetization, the frequency would have to be 600 Hz.
this isn't unreasonable, but i have not heard of them running that fast. however, knowing they might run those motors all the way to 8000 rpm, its not impossible they put an 8 pole motor in it, and 600 hz would be 9000 rpm.
but 45-50% magnet demagnetization seems incredible.
unless of course they run those motors at a leading power factor to provide capacitive exciton.. but that comes at a very high cost in copper losses in the stator.
if they utilize flux weakening in the upper half of the rpm range, then this means you have to say, double, that figure of 3320 watts per cubic inch.
anyhow, seems my figure of 74 watts per cubic inch per 60 hz seems rather low.