Investigation Into a Magnetic-Field-Modulated Brushless Double-Rotor Machine With the High-Strength and Low-Loss Modulating Ring Rotor

Aiming at the contradictory problem of low loss and high mechanical strength for the modulating ring (MR) rotor in traditional magnetic-field-modulated brushless double-rotor machine (MFM-BDRM), an MFM-BDRM with the high-strength and low-loss MR rotor is proposed. The key of the proposed MR rotor is to insert the nonmagnetic metal bar into magnetic block made by the silicon sheet laminations. First, to evaluate the influence of the proposed MR rotor on the performance of MFM-BDRM, a traditional MFM-BDRM with the same size is designed to compare their performances, like back electromotive force, torque, and torque ripple. Second, since the permeability of silicon sheet is not infinite, there are still some flux leakages passing through the nonmagnetic metal bar. The loss distribution law of the nonmagnetic metal bar under different permeabilities is investigated by the finite-element method. Besides, to ensure the safety of the proposed MFM-BDRM, the stress distribution law of the MR rotor is investigated under conditions of maximum speed, torque, and radial electromagnetic force.