I'm at a complete loss as to why the folks here have so much difficulty understanding that this hv to transformer to rectifiers bit has been done for a long time, and is VERY successful, and is much more reliable than any buck converter can hope to be with wild AC.
I can't navigate this new board at all, but in my diaries, there is a fairly detailed look at the AFRICAN WINDPOWER turbine here on Flinders Island. It has performed brilliantly for about 4-5 years now (except for the manufacturing faults as described in detail). It runs at a nominal 300volts ac, goes through a three phase transformer down to 48volts, and then to the batteries. done and simple. It has very very regularly done in excess of 24kwh per day for day after day after day. Yes it is in a good wind site, but it beats the pants of any other design I have seen for a nominal 1kw turbine. (after corrosion of the windings (not enough lacquer on them at manufacture) I rewound for about 1.5kw)
Paul.
It is critical to find out how many poles this turbine has, and it's rpm range. In the AWP instance, it is a 30 pole alternator. This is coupled to a 3.6m blade set. The rev range that is useable is quite great, but essentially, we monitor the input voltage/frequency, and when it approaches 180 volts or so, we cut in the transformer with ac solid state switches. (triac and an opto isolator) one phase wire is connected to the tranny all the time, and the other two phases are switched in at the step off voltage.
This is done so that the turbine can get up to a reasonable frequency before engaging the transformer. This makes the transformer part much simpler to deal with.... when the voltage drops below step off, we turn the two phases off until it recovers again..... do NOT use relays. They will rattle themselves to death quite quickly.
As soon as this step off is achieved, we simply rectify the 48v output and feed the batteries. They then feed the house inverter..... simple and very very sturdy.
I can't for the life of me understand all the fuss. I felt sure most of those commenting have read the stories.......maybe not worth the read?
If you have a very low pole count or very large rotor, the transformer will need to be a bit larger..... but remember, at low rpm, you don't need much transformer anyway, as the output will be low. As the power increases, the frequency will too, and the transformer will make a better fist of it. At very high rpm, the transformer will do even better.
Of all the stories I have read so far here, I have yet to see any small windmill system regularly put out this kind of kwh, or Hv controls run so free without magic smoke, or very fancy protection
We have never done an efficiency test so I can't tell you what that might be, but it works very well... no question about it..... and it hurts me to say so, but it does better than my larger axial flux, which can do much much higher outputs, but the transformer loading with the iron stator seems to match the load better than I am able to do with the axial flux wound for 48v.
So, find out what the rpm and pole counts are likely to be, and this will dictate your choice of transformer core and windings.
Lastly, you get the opportunity of using a HV dump load for overspeed if you wish, and a LV dump for the batteries. at a pinch you can use both for redundancy.
If I can handle it ....... it aint rocket science.
...............oztules
edit... found one of the posts here
http://www.otherpower.com/images/scimages/5171/awp_1.htmlIt goes into a fair bit of detail regarding the switching.
Heres part two if your desperate for some more reading
http://www.otherpower.com/images/scimages/5171/awp2a.html(fixed the link. G-)