about to start microwave genny

[bobanne]

After submitting a posting some time back " free microwave magnets " i am about to start this new unit. It will be made up of two Ford Ff250 disc rotors machined level with 32 magnets doubled up to make 8 north and 8 south poles on each rotor, so we end up with a total of 64 mags doubled up. Will run 10 coils of 1mm wire with 300 turns each, recycled from microwave transformers, i know this as an unusual matching but i want to see what happens, you would usually have more coils, 3 coils for each 4 mags. This might not work but we'll see. The 3 blades will have an approx diameter of 14 foot, this is required due to the weight of the rotors it will take a bit to get going but that will be good once it is turning.

Bob  

[electrondady1]

for single phase you would need 16 coils and for 3 phase you need 12. i can't see a relationship for 10 over 16 poles. how does it work?

[kitno455]

it makes 5 phase power, with a ton of wasted magnet power. the coils will need to have the traditional magnet-sized hole in them, but they will be spaced far apart. as weak as the ceramics are,  you should definately re-consider, and wind them as a more traditional 3 phase (12 coils). in this pic:

notice how the first coil is directly under a mag, but the second mag is doing nothing thru a coil. and dont even think about making that first coil larger to grab part of the next mag, cause then your mags are fighting.

now, all of that said, if you had a cogging problem, (say cause of iron inside your stator coils) you could probably rig up some number of coils such that this was like 'skewing', but likely not with an odd number of phases.

allan

[Chiron]

There is an advantage to more phases in a gen at low speed there is less "cogging" though with air core coils I don't know if this is a real problem. Also with 5 phase each rectifier only carries 1/5 of the total current instead of 1/3 with a 3 phase gen.

[kitno455]

sure, i agree, but 5 phases with extra mags makes no sense. he could make more use of the weaker mags if there was more coil. infact, 16 mags and 15 coils (15 phase) would be 'best' if you mix my thinking and yours.

the problem then becomes that his voltage is limited cause no coils are in series.

the utilities make 3 phase for a reason. it is the best trade off in terms of number of conductors (cost) vs power output (efficiency)

allan