Design and analysis of a low-speed double-fed brushless generator with fractional slot windings

A radial magnetic field modulated double-fed brushless generator (DFBG) with two types of fractional slot windings (i.e. single-layer full-pitch, double-layer short-pitch) for low-speed wind power generating system is designed, and the prototype machine with 60rpm has 15 rotor segments and two kinds of stator slots(30 and 36). Effects of different winding distribution and combination of poles and slots on stator EMF, electromagnetic torque, core losses and efficiency of the prototype generator have been analyzed. The 2D transient finite element analysis method is used for computating the characteristics of the generator. All studies show that the prototype DFBG with 36 slots double-layer short-pitch fractional slot windings is potential to apply in low-speed generating system.