Analysis of low-speed magnetic flux modulated doubly-fed brushless generator with different types of fractional-slot windings

The performances of a magnetic flux modulated doubly-fed brushless generator (FM-DFBG) with three types of fractional-slot windings (i.e. single-layer full-pitch, double-layer full-pitch, double-layer short-pitch) for low-speed wind power generating system are comparative analyzed, and the prototype machine with 60rpm has 20 rotor pole number and 108 stator slots. Two sets of stator windings’ pole number are 10 and 30 respectively. Effects of different fractional-slot windings on stator EMF, electromagnetic torque, and flux density in air-gap, core losses and efficiency of the prototype generator have been analyzed. The 2D transient finite element analysis method is used for computation the characteristics of the generator. The study shows that the FM-DFBG with double-layer short-pitch fractional-slot windings is potential to apply in double-fed low-speed direct-drive VSCF generating system.