I have found some test results that may help to explain things a little better.The first is a test on the alternator directly at 24v
The next is the same alternator into 12v.
The final one is the complete scheme.
You need to imagine that the direct connection at 24v is about right above 14 mph.
It will likely cut in about 10 mph with the prop running very fast but will not be very good below 12 mph.
The second curve is with the alternator loaded at 12v. You can regard this as being loaded at 24v via a fixed 2:1 boost converter. The cut in speed is halved so we should now start about 6 mph but the slope is far too high and by 10 mph the blades will be stalled.
By using current feedback to phase the gate pulses back the converter boosts from a progressively higher voltage as the prop sped increases, reducing the slope of the curve to match the prop. By about 14 mph the converter input volts will reach 24v and the main alternator will take over. Further increase in current will phase back the converter gate drive and finally it will stop.
The final curve has the low slope at low wind speed and high slope in high winds to keep the prop tracking the cube law power curve at the input of the alternator.
I hope this makes things clearer, I forgot that I had transfered this data from the old computer.
Flux
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