Loss and Efficiency of a Flux-Switching Permanent-Magnet Double-Rotor Machine With High Torque Density

The flux-switching permanent-magnet (PM) double-rotor machine (FSPM-DRM) used for hybrid electric vehicles has attracted considerable attention due to the compact structure and high torque density. Compared with the conventional machine, the FSPM-DRM suffers from more iron loss, PM eddy-current loss, and conductor eddy-current loss for its larger rotor pole numbers. The iron loss exists not only in the stator but also in the rotor, while its calculation becomes more difficult due to complex flux density waveforms. A more accurate analytical model for the iron loss, PM eddy-current loss, and conductor eddy-current loss calculation is proposed for the FSPM-DRM and compared with the results from finite-element method. Based on the calculated losses, the efficiency of the FSPM-DRM is also investigated. Some experimental results are reported, validating the numerical and simulation results.