Design of grid-connected to rotor type Doubly-Fed Induction Generators for wind turbine system

Doubly-Fed Induction Generators (DFIGs) are widely used for modern wind turbines. Although the stator winding of DFIG is directly connected to a grid while a rotor winding is connected to converters, it has a large outer size because of the high current in the stator winding. This paper proposes a grid-connected to a rotor type DFIG where rotor winding is connected to the grid instead of stator winding. In order to verify the size reduction of the proposed type, a loading distribution method (LDM) is utilized. Then the characteristic analysis is performed using the equivalent circuit method (ECM). As a result, the total volume of the proposed type was decreased by about 10.73 %. In addition, the total core weight of the proposed type was also decreased from 24.5 kg to 21.9 kg.