A New Dual Stator Permanent Magnet Machine Based on Field Modulation Theory

Increasing industrial development puts forward high requirements for the performances of stator permanent magnet (PM) machines, such as torque density and efficiency. The paper proposes a new dual stator PM machine based on field modulation theory (DSPMM), which employs the intermediate rotor participating in the electromechanical energy conversion of the internal and external machine. The proposed machine has the advantages of high torque density and high efficiency and solves the problem of insufficient space utilization of a single stator machine. The evolution process and working principle of the proposed DSPMM are studied. The flux-switching-type PM (FSPM) and the flux-reversal-type PM (FRPM) are employed in the proposed DSPMM, which forms four representative machines. For a fair comparison, the proposed machines employ identical key parameters, i.e., PM volume, the outer radius of the outer stator, and active airgap length. Based on finite element analysis (FEA), the electromagnetic performances of the four representative DSPMM under no-load and rated load, and different copper consumption conditions are analyzed and compared. The calculated results show that the proposed DSPMM with inner FSPM stator and outer FRPM stator can provide high output torque, low torque ripple, high power factor, and high efficiency.