Torque Characteristics of High Torque Density Partitioned PM Consequent Pole Flux Switching Machines With Flux Barriers

Abstract

—Unique double salient structure of Permanent Magnet Flux Switching Machines (PMFSM) with both Concentrated Armature Winding (CAW) and Permanent Magnet (PM) on stator attract researcher’s interest for high speed brushless application when high torque density (Tden) and power density (Pden) are the primal requirements. However, despite of stator leakage flux, high rare-earth PM usage, PMFSM is subjected to slot effects due to presence of both PM and CAW in stator and partial saturation due to double salient structure which generates cogging torque (Tcog), torque ripples (Trip) and lower average torque (Tpvg). To overcome aforesaid demerits, this paper presents Partitioned PM (PPM) Consequent Pole Flux Switching Machine (PPM-CPFSM) with flux barriers to enhance flux modulation, curtail PM usage and diminish stator leakage flux which reduces slotting effects and partial saturation to ultimately reduces Tcog and Trip. In comparison with the existing state of the art, proposed PPM-CPFSM reduces 46.53% of the total PM volume and offer Tpvg higher up to 88.8%, suppress Trip maximum up to 24.8%, diminish Tcog up to 22.74% and offer 2.45 times Tden and Pden. Furthermore, torque characteristics of proposed PPM-CPFSM is investigated utilizing space harmonics injection i.e. inverse cosine, inverse cosine with 3rd harmonics and rotor pole shaping techniques i.e., eccentric circle, chamfering and notching. Detailed electromagnetic performance analysis reveals that harmonics injection suppressed Tcog maximum up to 83.5%, Trip up to 40.72% at the cost of 4.71% Tpvg. Finally, rotor mechanical stress analysis is utilized for rotor withstand capability and 3D-FEA based Coupled Electromagnetic-Thermal Analysis (CETA) for thermal behavior of the developed PPM-CPFSM. CETA reveals that open space along PPM act as cooling duct that improve heat dissipation.