Yes at least I know that you want to charge batteries.
When you are battery charging you will be effectively clamped to battery voltage so your rating will be similar to Dan's.
I am not sure how much luck you are going to have with direct heating without batteries. Do you wish to continue to charge the batteries or is it to be diverted to a completely different heating scheme. If you keep things at 120v and use the controller to keep banging more load on to maintain the 120v limit you will be in stall mode just as for the battery charging.
It will work but you will be restricted by the stator heating problems just as in battery charge mode.
Not sure if you intend to run the heaters on dc or balanced 3 phase ac. Either way your stator is more suited to higher voltage and 240v heaters would make far more sense.
You would presumably start with a base load heater that allowed start up and produced a match to lower winds ( probably little heat to be worth catching below 10 mph) you would then use the controller to add load as the wind picks up in such a way as to let volts rise with wind speed. This would get you to about 240v at just over 20 mph. If you are stuck with 240v heaters you would then have to increase load more rapidly in higher winds to clamp the voltage to your heater limit of 240. This would bring yopu towards stall and make things more controllable. You would need to furl when you reached the stator temperature limit when loaded into 240v.
At 240v load you would have potentially 4 times the heating power compared wioth clamping at 120v for the same stator temperature limits.
Don't know how you intend to use the controller to do this, ideally a pwm IGBT controller would be the ideal but crash bang control with solid state relays may be good enough.
I think I would be tempted to go at this another way, it would require odd value heaters but would give a simpler solution.
If you kept to battery charging with a diversion controller you would get all the diverted heat when batteries are full. You would be working stalled and limited by stator loss. Now if you added a series heater between the rectifier and the battery it would bring you out of stall, battery charging results would improve and you would have more heat from the dump load. You would also be able to use the heat in the series resistor when battery charging or dumping. If you proportion this resistor right it would improve your blade match and the heat dissipated in the resistor would not be heating your stator. Better battery charging and a heating scheme that does not involve any experimental technology.
Flux