AERODYNAMIC & ELECTROMAGNETIC MODELING & ANALYSIS OF A VARIABLE TORQUE GENERATOR FOR WIND TURBINE APPLICATIONS

The use of a variable torque generator (VTG) with a movable stator relative to the rotor in the drivetrain of a wind turbine is investigated theoretically and computationally. This feature allows the use of a larger capacity generator in wind turbines to increase the rated power in high wind speeds and still keep them in operation in even lower than cut-in speed ranges. Thus, by harnessing more wind power throughout the entire power curve of the wind turbine, from the new cut-in speed to the cut-out speed, the efficiency of the wind turbine can be increased. The stator and the frame of the generator can be attached to a movable frame and changes in overlap can be mechanically achieved by a worm and worm gear system connected to the movable frame. Theoretical analyses together with computational methods on several wind turbine generators illustrate the advantages of having VTG feature in terms of decreasing the cut-in speed, increasing the rated power, and at the end improving the efficiency of a wind turbine. The aerodynamic and electromagnetic properties of the wind turbine are combined to make the best estimation on changing in overlap. At the end, simulation and mathematical results are presented and possible advantages of VTG with focus on on-shore wind turbine applications are discussed