If you have built the turbine accurately to the plans you will gain nothing with a voltage booster. It should work well in low winds as it is.
Either you have not done something right or you have no useful wind. If you have no wind you can play with all the tricks in the world and it will not help.
If you have useful wind but have done something wrong such as used the wrong number of turns or too large an air gap then a boost converter may help.
If it is the 5 phase machine you will need a conventional boost converter with mosfet, inductor and diode. If you have wound the machine for 3 phase then the 3 mosfet boost converter using the winding inductance will be a better choice. I gave some basic details in a diary entry called matching the load but it was a while ago and I wouldn't be able to find a link to it.
Flux