Comparison of Slot/Pole Topologies of Variable Flux Reluctance Generators for Aircraft Applications

This paper investigates variable flux reluctance generators and their usage in aircraft. They are well suited for high speed generator applications with their simple rotor structure composed of only electrical steel lamination without permanent magnet and other loads that are critical for their centrifugal stress effect at speed. 6/4, 6/5 and 12/10 topologies are examined in terms of back-EMF and the distribution of radial electromagnetic forces which occur through air gap between rotor and stator. Moreover, it is shown that there is a trade off between back-EMF and radial air gap force distribution on polar axis. Finally, the effect of these large air gap radial forces in terms of mechanical deformation are analyzed in Ansys Workbench Steady-State Structural Finite Element Tool.