# Alternator rotor magnet pattern question

#### henry newton

Joined May 5, 2008
11
1. In an axial flux alternator, the poles of the magnets are arranged or alternate in a N-S-N-S pattern around the circumference of the rotor disk.My question is,will the axial flux alternator generate electricity if the poles of the magnets are arrange in a (let say) N-N-N-N pattern around the rotor disk.If yes what kind of current will it generate (d.c or a.c).I personally expect a d.c.Although i have not perform this experiment.I would like for you guys to experimentally confirm this.

2.I live in Nigeria, and believe it or not there is no place where one can buy neodymium magnets and i am badly in need of them.so i would like for someone(i mean a member of this forum)living in the US to buy some for me.Of cause i will have to send him first the money through Western Union Money Transfer and the magnet would have to be delivered via either UPS,FedEx or DHL.which ever one is most suitable for this kind of delivery.

If anyone is up to this,please email me at ( <snip>). I will send you the specification of the neodymium magnets that i want and you will find out the total cost, plus cost of shipment in dollar ( prefarably in Nigeria Naira if you can do the conversion or compute the exchange rate).Also you will have to tell me what personal data you need from me to facilitate the transfer of the magnet via either UPS,DHL or FedEx .You will send me your personal data that will allow me to send the money via Western Union Money Transfer.

email me at <snip>

Thanks

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#### jpanhalt

Joined Jan 18, 2008
8,106

Henry Newton.

#### TechMate

Joined Mar 24, 2010
1
1. In an axial flux alternator, the poles of the magnets are arranged or alternate in a N-S-N-S pattern around the circumference of the rotor disk.My question is,will the axial flux alternator generate electricity if the poles of the magnets are arrange in a (let say) N-N-N-N pattern around the rotor disk.If yes what kind of current will it generate (d.c or a.c).I personally expect a d.c.Although i have not perform this experiment.I would like for you guys to experimentally confirm this.

I found this old unanswered question when searching for other things.
The thread might be finished, but it might be of interest to have an answer to the technical question any way.

The answer to the question is a AC, but much weaker.
You must first consider where the magnetic flux lines are flowing, i.e. as many big loops from one en to the other end of the same magnet.

Current is generated in an electric wire when the wire is cutting through the magnetic flux loops.

As they are loops, the wire has to cut through the loop twice. First when getting into the loop and second when getting out of the loop.
The direction of of current will change as a consequence of whether the wire is going out or in to the loop.

When having magnets located N-N-N as described the quote. The loops are orientated more or less as old flowers i a vase, i.e. the flowers are hanging down on the side of the vase. The vase represent the magnet.
Now if You want to cut through the flowers just on top of the vase with a wire, you may notice that you first start cutting into the loops, but when coming closer to center of the vase you are cutting out of some loops while still cutting in on others. Some loops in the center of the vase will be cut in different directions simultaneous. Finally you will be cutting out of all loops.

From this we can draw the conclusion that it is very inefficient way to design an alternator. Even when considering a single wire we have forces working against each other.

To correct the weaknesses above the magnets are located N-S-N-S and preferably a second disk magnets located S-N-S-N
The disks are located so that a N on one disk is close to S on the other disk.
The magnetic flux will now look very different. The strong flux will between the closest N-S poles.

Now You can insert coils of wire between the disks. The mid diameter of the coil should be the same as the c-c for the magnets. In this way the one part of the coil is cutting out of a N-S flux as the other part is cutting in of a S-N flux. This means that both actions work in the same direction.

Regards TechMate