Generator Excitation Control. All generators require magnetic excitation in order to produce power. The excitation required for an induction generator comes from the utility grid. If the generator and generator controls are not carefully designed, the excitation losses can substantially detract from power output of the turbine, particularly at low wind speeds when there is very little energy available in the wind.
BECAUSE INDUCTION GENERATORS MUST HAVE UTILITY POWER AVAILABLE BEFORE THEY CAN PRODUCE POWER, THEY ARE INHERENTLY SAFE AND CANNOT ENERGIZE THE GRID WHEN UTILITY POWER FAILS
Aerostar has made technological advances in increasing generator efficiency by designing a control system that monitors wind conditions and reduces excitation losses at low wind speeds, greatly increasing energy capture. The (patent pending) design substantially increases the useable generator power output at low wind speeds compared to standard induction generators. 
As an example, a standard 10 kW induction generator may have losses of 800 to 1000 watts at the low power levels commonly found at low wind speeds. The Aerostar design reduces these losses by about 2/3. This means that every hour the turbine runs at low wind speeds you would gain in excess of 1/2 kWH more than a similarly sized induction generator without our excitation control. In a low wind speed area, this can amount to an increase in power production of more than 300 kWH per month when compared to a standard 10 kW induction generator.
Inverter based systems also suffer losses from the conversion of power from AC to DC then back to AC again. Our induction system has none of these losses. That's why Aerostar turbines are so efficient.