Your generator is a low frequency unit, for 50 Hz the RPM is 500, so at 225 RPM the output frequency is 22.5 Hz and of course lower frequency ( 5.2 Hz) at lower 52 RPM.

No way to use transformers to bring the power down economically.

You need to rectify and do a DC/AC or DC/DC conversion to a workable voltage.

You could have a dual conversion ( with MPPT), from low voltage to 700 volts and from there a DC/AC or A DC/DC converter.

Conversion depends on what you want to do.

You say 48 volts battery bank -- what size -- amp-hour

The DC/DC converter could be a full bridge IGBT with PWM for a good charging battery profile.

The problem is the availability of the 5 to 6 KW DC/DC or the DC/AC converters.

A high voltage Buck down converter is, as well, possible -- it is a major effort to do, because the major ratio is 700/57 volts = 8.77 ratio that at this power needs to be handled carefully for MPPT capabilities.

Regards

Wow - pretty impressive results, I'd say you deserve a pat on the back for this one. I've been following your project since you first posted it here.

The high voltage and low amps should cut down the amount of heat generated in the stator. Also it should be pretty efficient over a longish run of wire. At 225 rpm that should work out to about 22.5 HZ (provided my brain is operating correctly!)

Just out of curiosity have you worked out what you're going to do downstream of this alternator - transforming, storing, or using it as you go?

That constant speed mechanism for the prop is looking pretty nice too!

I'd love to see what you're thinking as far as blades (material, profile, etc.)

Also, I don't know what you're thinking about to tap this power, but the relatively high voltage sould work well to generate heat through a resistive element like a hot water heater element.

I think that your results
are quite impressive.

Could you please publish a bit more
about the design of the alt.
How much you put silicon
steel laminates on that
and which way are they arranged.

I'm interested in seeing
your design for the blades.

your load was 50 ohms, what was the resistance of your source, what was the resistance of each phase?
did you calculate the power lost in the coils?
P = I^2 x R,  R = resistance of your coils.

Great output for only 24 magnets!, did you have any cogging?

i would suggest that you use lock-nuts, or put "lock-tight" on your nuts if you havent done already, as the vibrations may loosen them over time.