A Doubly-Fed Variable Flux Reluctance Machine with Integrated Stator Field and Armature Winding and Rotor Armature Winding

This paper presents a novel doubly-fed variable flux reluctance machine (DF-VFRM) with dual stator and rotor armature windings. The stator armature and dc field winding are integrated to reduce the winding resistance. Operation principle of DF-VFRM is introduced based on a 6-stator-pole and 5-rotor-pole (6s/5r) machine topology. In addition, its electromagnetic performances including inductance, back-EMF, cogging torque, electromagnetic torque and unbalanced magnetic force (UMF) are analysed by finite element (FE) method. Besides, three other electrically excited doubly-salient structure machines including conventional VFRM, wound field synchronous machines (WFSM) with 6s/4r and 12s/4r, viz. fractional-slot and integral-slot machines are optimized and compared with the novel DF-VFRM. The results show that the novel DF-VFRM has 30.2%, 30.2% and 17.7% higher average torque than VFRM, 6s/4r and 12s/4r WFSM, respectively. Besides, the novel DF-VFRM has a good fault-tolerance capability due to its independent dual armature windings.