Btw, obvious improvement is missing - u input 500W and get 2kw, why not short-curcuit the whole thing? Feed the motor not from the grid but from the output. This way u will still get 1.5kW output and no need for the grid AC!
A 50cm exhaust fan will give 1.5 mph and that is not enough, wind turbine won't work with that, 3 x 1.5 = 4.5 mph might do but you will get very little to bother about. 7 mph or 3 m/s is really the minimum.