Scheme optimization of an axial magnetic-field-modulated brushless double-rotor machine

The magnetic-field-modulated brushless doublerotor machine (MFM-BDRM) system, mainly consisting of the MFM-BDRM and a conventional permanent magnet synchronous machine, is a novel power-split concept to realize both the speed and the torque control of the internal combustion engine (ICE) for hybrid electric vehicles (HEVs). Without brushes and slip rings, the system has significant potential advantages such as low maintenance and high heat dissipation capacity. As a key part of the MFM-BDRM system, an axial MFM-BDRM is investigated in this paper. As the axial MFM-BDRM realizes stable torque transmission based on the effective harmonic magnetic field, modulation effect of the machine is discussed. In order to determine the scheme, electromagnetic performance is evaluated with models of different combination between the pole-pair number of the stator and that of the permanent magnet rotor. After that, the preferred scheme is optimized to improve the torque transmission capability. The above analyses are simulated with the three dimensional (3-D) finite-element method (FEM).