Dual rotor magnetically geared power split device for hybrid electric vehicles

The paper presents a theoretical and experimental investigation into a dual rotor magnetically geared power split device for hybrid electric drivetrains. It is shown that the modulation of magnetic field created by rotor permanent magnets by an array of ferromagnetic pole pieces results in two dominant space harmonics in the airgap adjacent to the stator. Thus, special attention is given to the design of the stator and the selection of the winding configuration, and the effects of air gap space harmonics on performance of the device are discussed. A full-scale prototype for a mid-sized passenger vehicle is designed, built and tested, and the operation as a power split device is demonstrated and it is shown that efficiencies in excess of 94% can be achieved. Furthermore, torsional vibration attenuation by the proposed device is discussed and experimentally demonstrated on a purpose built test rig.