Torque Analysis of Magnetic-Field-Modulated Double-Rotor Machines with Virtual Work Method

The magnetic-field-modulated brushless double-rotor machine (MFM-BDRM) is a new power-split device for hybrid electric vehicles (HEVs). A simple and intuitive torque calculation model for the MFM-BDRM is proposed to estimate the torques of the MFM-BDRM rapidly and investigate the torque characteristics of the MFM-BDRM directly. The structure and the working principle of the MFM-BDRM are first introduced. Then, the torque expressions of the PM rotor, the modulating ring rotor and the stator are deduced based on virtual work method. The deduced torque expressions show the effects of the machine parameters on the electromagnetic torque of the MFM-BDRM clearly. Comparisons between analytical calculations and finite element calculations are carried out. The analytical results are in good agreement with the finite element results, verifying the accuracy of this model.