A Fractional Slot Concentrated Winding (FSCW) configuration for outer rotor squirrel cage induction motors

Fractional Slot Concentrated Windings (FSCW) or tooth windings have been proved to be very beneficial for synchronous and permanent magnet (PM) motors. However, the abundance of space harmonics in the air gap flux have rendered FSCW configurations unsuitable for induction motors. This paper proposes the use of a multi-layer FSCW wound around two layers of stator slots that eliminates sub (a fraction of fundamental) and higher order space harmonics and provides a non-overlapping winding arrangement. This winding configuration has several advantages like high torque density, shorter end-winding length and easier manufacturability for outer rotor squirrel cage induction motors for pumps, fans and in-wheel hub drives. A design comparison is performed between the proposed winding configuration and a conventional distributed winding.