Design and Analysis of a Dual-Stator Sub-Harmonic Vernier Machine for Reconfigurable Torque Operation
Article
Rafin, SMSH, Ali, Q, Mohammed, OA. (2026). Design and Analysis of a Dual-Stator Sub-Harmonic Vernier Machine for Reconfigurable Torque Operation
. IEEE TRANSACTIONS ON MAGNETICS, 10.1109/TMAG.2026.3716419
Rafin, SMSH, Ali, Q, Mohammed, OA. (2026). Design and Analysis of a Dual-Stator Sub-Harmonic Vernier Machine for Reconfigurable Torque Operation
. IEEE TRANSACTIONS ON MAGNETICS, 10.1109/TMAG.2026.3716419
This paper proposes a permanent-magnet-free dual-stator sub-harmonic vernier machine (DSSHVM) using inner and outer stators with a shared wound rotor for reconfigurable torque operation. Each stator includes a main ABC winding for vernier torque production and an XYZ winding for sub-harmonic brushless excitation, while the rotor harmonic winding and rectifier generate the field current without permanent magnets, brushes, or slip rings. The proposed topology supports three excitation states, including dual-stator, outer-stator, and inner-stator excitation, enabling high-torque and reduced-torque operation using the same machine structure. Two-dimensional finite-element analysis verifies brushless field-current generation, dual-air-gap torque production, excitation-state-based torque reconfiguration, wide-speed operation, and overload performance. The unoptimized dual-stator case produces 32.98 N m average torque with 25.47% torque ripple. After 4-degree rotor-skew optimization with 9 slices, the average torque is 30.60 N m and the torque ripple is reduced to 6.65%. Compared with the reference DMDS-HRSVM, the optimized DSSHVM achieves higher average torque, lower torque ripple, and improved torque and power densities under similar dimensional constraints. The results show that the proposed DSSHVM is a promising brushless PM-free machine topology for traction-oriented reconfigurable torque operation.
