Scaling Effect on Inter-Turn Short-Circuit of PM Machines for Wind Power Application

This paper proposes a general analytical model of surface-mounted permanent magnet (SPM) machines with series-connected coils under inter-turn short circuit (ITSC) fault. One prominent feature of this model is that the air-gap and slot-leakage components of inductances under fault are calculated separately, which consider the influences of pole number and spatial distribution of coils. In the model, winding function approach (WFA) is used to calculate the air-gap inductance components by considering all space harmonics whilst slot-leakage inductance components are obtained by using slot permeance method. The proposed faulty machine model built in Matlab/Simulink is validated by time stepping FE simulations for a 3kW 96-slot 32-pole SPM machine. The model is suitable for the fast evaluation of fault performance of SPM machines and the development of faulty model considering core saturation if necessary. Other power ratings (0.5MW and 3MW) have also been investigated to study scaling effect on machine fault-tolerant capability.