Comparative Study on Dual Rotor Permanent Magnet Switched-Flux Generator in U-Shape and E-Shape Stator for Counter-Rotating Wind Turbine Applications

In this paper, a comparative study on E-shape stator dual rotor switched-flux PM generator (ESS-DRSFPMG) and U-shape stator dual rotor switched-flux PM generator (USS-DRSFPMG) two types of electrical machines for counter-rotating wind turbine application has been conducted to improve the power density of the generator. Two categories of electrical machines feature a back-to-back connection of the yoke of the outer and inner stators, which physically separates the armature windings of the inner and outer ports, contributing to the reduction of the coupling between the two sets of windings. In addition, a common flux path is constructed for the armature flux of the inner and outer ports, facilitating torque improvement. Three topologies with different slot/pole combinations are comprehensively investigated using finite element analysis (FEA). Compared with the traditional USS-DRSFPMG, the cogging torque and torque ripple of ESS-DRSFPMG significantly reduced and torque density ascended.