Dual-stator, spoke-type ferrite permanent magnet motor with phase-group concentrated-coil windings using auxiliary inner stator

This paper proposes a dual-stator, spoke-type ferrite permanent magnet motor (FPMM) with phase-group concentrated-coil (PGCC) windings using an auxiliary inner stator to obtain high motor performance and improve the thermal conditions. In the proposed FPMM, the utilization of the PGCC windings, together with the spoke-type magnets and an unaligned arrangement of two stators, aims at improving torque density and suppressing torque pulsations. Since the inner stator suffers from thermal issues due to the relatively higher electric loading than the outer stator and difficult heat dispassion, the PGCC windings in the proposed FPMM are fed only on the outer stator, featuring an auxiliary inner stator with only iron core. Consequently, the proposed FPMM with PGCC windings could obtain high performance, including high torque density and low torque pulsations, and improve the thermal conditions as well as release manufacturing difficulties by removing windings from the inner stator. Furthermore, a quantitative comparison is carried out among the proposed FPMM with the auxiliary inner stator, the referenced FPMM with PGCC windings in both outer and inner stators, and the referenced FPMM with a single stator, by the aid of a finite element method (FEM). Finally, the operating range characteristics of the proposed FPMM is examined to satisfy the demand of applications with an over 3:1 speed range.