Calculation Method for Rotor Slot Leakage Inductance of Virtual-Slot Short-Pitch Wave Winding

In order to calculate the slot leakage inductance of the virtual-slot short-pitch rotor winding in a doubly-fed induction generator (DFIG), the arrangement of a phase belt winding in the generator slot was studied from the structural principle of the virtual-slot short-pitch wave winding. Further, according to the self-induction and mutual-induction characteristics of conductors, the distribution of leakage flux linkage in the virtual slot of the short-pitch winding for rotor was derived by differential algorithm. Then, a calculation method was developed for slot leakage inductance of short-pitch windings with an odd and even number of virtual-slots, and its validity was verified through a case study. The results show that for the virtual-slot short-pitch winding, whether the number of virtual slots in the short-pitch windings is odd or even, the leakage inductance value is approximately the same. For the rotor using equivalent real slots, however, the leakage inductance is nearly twice that using virtual slots.