Single-Phase Generator: Troubleshooting Power Output

[michael1965]

Hi,

Why won't a generator composed of a stator that has 9 coils (each connected to it's neighbour in a ring until line out), and a rotor that has 10 permanent n50 magnets (NSNS...) generate useable electricity?

 

[Baluncore]

Welcome to PF.
Each coil will generate a different phase. The sum of all the phases is a closed pentagon, so the difference voltage is zero.

 

[michael1965]

So it wouldn't produce a charge?

If the electrons in the wire are excited, then surely a voltage is produced?

 

[Averagesupernova]

So it wouldn't produce a charge?

If the electrons in the wire are excited, then surely a voltage is produced?

----

Welcome to PF.
Each coil will generate a different phase. The sum of all the phases is a closed pentagon, so the difference voltage is zero.

 

[michael1965]

What if each coil was separate.

 

[Baluncore]

If each coil was separate then each coil would produce an output voltage.
You would need to rectify each independently, then combine them as DC.

With the odd number of 9 coils, there are none that could be combined to sum efficiently by reversing the connections of opposite coil pairs.

I must have been asleep when I posted #2. For “closed pentagon” read “closed regular polygon”.

 

[michael1965]

What if there were 10 magnets, and 10 independent coils?

 

[Baluncore]

If the coils are independent then it may actually be better to have 9 coils so one is always generating current. Independent coils require rectification before they are combined.

If 10 magnets and 10 coils then coils can be in series, each then needs to produce less voltage, so it can have less turns of thicker wire. It will produce an AC output.

 

[michael1965]

So, 10 magnets with 9 independent coils would have 90 coils generating a current per turn, whereas 10/10 would have 100 coils generating a current per turn. Both would be AC (?).

You say "If 10 magnets and 10 coils then coils can be in series, each then needs to produce less voltage, so it can have less turns of thicker wire. It will produce an AC output." Why do we want a lower voltage? Why not wind it long and thin, and get a large voltage?

On the subject of AC. If a magnet (n) passes over a coil it will excite the electrons in a wave (U or n?). As the next magnet (S) approaches, the electrons are excited again, this I believe is AC. If I have one single coil and 10 magnets of alternating polarity, then surely this would produce an AC. Similarly, if I have 10 coils and 10 magnets of alternating polarity this would also produce an AC in each coil. So, as long as the magnets are of alternating polarity, the charge produced should be AC, regardless of the number of magnets, the number of coils etc...?

Thanks for answering my questions.