Question 1)
I am trying to make a miniature alternating current (ac) generator from elementary first principles. Before I waste a lot of time (and copper wire), I wanted to check if the configuration as shown will actually produce a voltage, however small. The rotor (35mm dia) is fitted with 8 neodymium miniature bar magnets. I have read that adjacent magnets should have opposite polarities as shown (N,S,N,S etc.). I assume my arrangement is OK?
Main issue is how to wind the stator coils. I have read that these should also be wound differently in adjacent coils, for example starting at the 12pm position, clockwise, then anticlockwise, then clockwise etc. (The coils are wound in such that they make a loop 'facing' the bar magnet(s) as they rotate.
Question 2)
Assuming that this not all complete junk, what kind of phase (?) generator would this be?
Question 3)
Assuming that the rotor is spinning at e.g. 1000 rpm, what would the frequency of the induced voltage be and how would I calculate that? Presumably something to do with number of changes in magnetic field per rotation x rotation speed ?
Best Answer
Question 1
The magnet arrangement is ok. Rather than wind the coils differently, it may be easier to wind them the same and connect them as required to make the outputs additive rather than opposing each other.
Question 2
Since the number of coils is not evenly divisible by three, the coils must be connected to make a single-phase generator. Perhaps it could be connected as a two=phase generator, but that would be more complicated and I think not advantageous. An 8-pole, single-phase generator is probably best.
Question 3
Frequency (Hz) = RPM X Number of Poles / 120
Additional Advice
You should consider the magnetic circuit and the variation of the air gap. The diagram should show the iron.