A Novel Dual-stator Permanent Magnet Vernier Machine with Magnets in Rotor and Both Stators

This paper proposes a novel vernier machine which could offer higher torque density compared with the regular permanent magnets (PM) vernier machine. The proposed machine has two stators and one rotor sandwiched between the two stators. The three-phase winding is placed in the outer stator slots and Halbach array PMs are placed in the slot openings. Both inner stator and rotor have consequent pole structure with PMs. Each of the three kinds of PMs can produce working harmonic magnetic field, and then induce back electromotive force (EMF) in the windings with the same frequency and phase angle. The back EMF can be hugely enhanced due to the trinal magnetic modulation effects, which lead to a higher electromagnetic torque. After optimizing the Halbach array PMs, width of inner stator PMs and width of rotor PMs, the machine can produce a higher torque and torque ripple is lower. The electromagnetic torque is 22% larger than regular surface mounted PM vernier machine.