Axila flux voltage question

[TDC]

If the number of magnets and coils were reduced by 1/3 in an axial flux pma, would the voltage per revolution be reduced by 1/3 at the same current?  Rotor and stator diameter would be reduced accordingly.
Thanks.

[Flux]

No, but it is a difficult question to answer without much more details.

Flux

[TDC]

Thanks Flux, you are great help! What info is needed? I'll put together a more detailed response later. I'm planing a 2 meter version of Chris Olson's 3.2 meter ferrite for high voltage, Midnight Classic MPPT and chain drive.  Hugh's 2 meter ferrite design uses wedge shape coils and the same 2 x 2 x 1" magnets, 12 pole/9 coil.  I'm thinking of a 8 pole/6 coil version with 4:1 gear ratio.

[Flux]

Basically if you take an existing alternator and leave out 1/3 of the stator you get 2/3 of the volts.

Once you start taking out magnets the total flux falls and outputs start to fall quite rapidly. Not only does the voltage fall but the total power out falls off rapidly. As you compensate for the fall in volts with more turns, the resistance and reactance start to have a drastic effect on the output.

Unless you compensate with an increase in speed the power out drops rapidly with loss of flux. With a smaller wind rotor diameter you will have higher speed with the same gear ratio so things  will be better than from the reduction in magnets alone. This and the large reduction in wind rotor output may work out.

At the moment I don't have the original details but what you are planning should be possible. If you use the Classic you need to keep alternator efficiency up to get best results so you may be able to use a bit less magnet don't skimp on the alternator too much. 33% reduction in magnet may be a bit drastic unless you keep the alternator speed up but watch the CF forces on those large magnet blocks.

Flux

[TDC]

I realized I probably knew the answer from other posts, 2x diameter gives 4 times the power?   I should probably just  build to Hugh's spec  for 48v (9 coils, 180 turns of #17)  and use the chain drive to increase voltage close to 150.  Or wind two in hand for 24v or 48v and test various sprocket ratios.  The neat thing is the gen could be used normally or chain driven.  I could make a setup on the milling machine and measure input torque and measure (rather than calculate) efficiency of various setups, both direct and chain driven. More fun.