Performance analysis of a hybrid ferrite IPM/SynR traction machine with axially combined rotor structure

The paper presents the performance analysis of a hybrid Ferrite Interior Permanent Magnet (IPM)/synchronous reluctance (SynR) traction machine with axially combined rotor structure. First, a hybrid rotor with axially combined structure of Ferrite IPM rotor and SynR rotor is introduced. Then, performance analysis is presented. It is shown that due to the axially combined structure, the hybrid concept machine could achieve a significant lower copper and iron loss in the high-speed operation region, compared with the original Ferrite IPM machine. It is demonstrated that due to the difference in optimum operation between the IPM and SynR machines, the two-rotor parts could be circumferentially shifted by an optimum angle for a specific control target achievement, i.e., maximum torque per amper (MTPA) or minimum energy consumption over a specific driving cycle. Therefore, an extra degree of freedom on design could be obtained for the hybrid rotor structure. The proposed concept is validated via FEA benchmarking by a high-speed high-power (12,000rpm and 80kW) Ferrite IPM traction machine. It is shown that in comparison with the Ferrite IPM machine, a reduction up to 26.29% in energy consumption over WLTP driving cycle could be achieved for the proposed hybrid rotor concept machine.