Another day, another wiring scheme...
We tried running all the windings in series star configuration, but that did not work too well. Maximum power was about 500 Watts in a pretty good wind, so we took it down again. One more thing we tried was to measure AC frequency at the moment of feathering, and appearantly it only feathers when we're doing 250 RPM. So, we decided to change it to Delta / parallel configuration and to tighten the spring a bit to increase the RPM at which the machine feathers.
It was extremely cold yesterday, so we gave up when it started getting dark on top of that in the hope that today would be better (it was -20 yesterday). So, this morning we went out full of fresh energy only to find that now it was -30.... go figure. Anyway, us Dutch boys are not made of sugar, so we kept at it until it was done. I had messed up the marking of the wires so we had a bit of a puzzle there, but in the end we worked it all out.
Then the tractor wouldn't start. No wonder, -30, no block heater and a diesel. The perfect combination. Jumpstarting it from the truck worked after a while and we lifted the tower back in position. At that moment there was a little bit of wind, and we could see some charge going in to the batteries, but not as much as we'd normally see at that RPM, mostly because of the delta configuration causing a lower voltage to be present on the output.
This led to my earlier posting about boosting the voltage, and Victor has given us a very good idea on how to proceed with this, use the coils in the machine as the inductive portion of a boost circuit by shorting them out during small periods and then to capture the resulting spike.
As soon as there is some wind I'll give that a shot, see if we can do maximum power point tracking that way.
maybe use the feedback from the shunt and the input voltage to figure out the 'ideal' puls-pause combination.
One of the effects from todays modifications is that I expect the 'high' end to give quite a bit more power than it did so far, we'll see if that is correct or not.
Two days ago at night I couldn't sleep and started working on documenting the machine in detail on reresource, I've created a section for windmill plans there. If you want to have a look at the 'work in progress' then you can find it here
