Torque performance analysis of three-phase flux reversal machines for electric vehicle propulsion

Flux reversal machines (FRMs) have a great potential in the field of electric vehicle (EV) propulsion due to their high torque density, robust structure, fast response, etc. This paper focuses on the analysis of the torque performances including average torque, cogging torque and ripple torque of three-phase FRMs. First, the general expressions of instantaneous torque and pulsating torque are analytically derived based on flux harmonic theory. Then, using the proposed equations, the effects of stator/rotor slot combination, split ratio, PM thickness, stator and rotor slot opening ratio on the torque performances are investigated and analyzed, which give a prediction for maximum achievable torque density and minimum possible pulsating torque of a FRM. Finally, the theoretical analyses are validated on a 12-stator-slot /17-rotor-slot FRM prototype.