Development of a Three-Phase Dual-Rotor Magnetless Flux Switching Generator for Low Power Wind Turbines

This article presents a new three-phase flux switching generator (FSG), which is mainly designed for variable-speed low power wind turbines. The magnetless structure of this generator not only reduces the machine cost but also increases the flux controllability. In order to shorten the field and armature end-windings, non-overlapped concentrated windings have been ingeniously incorporated into the dual-rotor middle-stator structure. A parametric study of both stator and rotor pole arcs is carried out, targeting maximum generated EMF, and minimum cogging torque. Using finite element method, the performance of the final design is analysed. Through the ac-dc rectification, the generated EMF is rectified to give out the dc output voltage, which can be regulated by controlling dc excitation current, and accordingly, the machine can behave as a constant-output dc generator under different conditions of rotor speeds and load currents. Finally, a prototype has been manufactured and experimented to prove its validity for dc microgrids integrated with wind generation systems.