A flux-concentrating external-rotor switched flux hybrid magnet memory machine for direct-drive automotive applications

In this paper, an external-rotor switched flux hybrid switched flux memory machine (ER-SF-HMMM) with effective flux-concentration is developed. Due to external-rotor configuration, the stator design space is enlarged, and hence the geometric compromise existed in internal rotor (IR) counterpart is resolved. Thus, the proposed ER-SF-HMMM can perform higher torque capability and flux adjustability than the IR one. In addition, since the current pulses are energized to perform the online magnetization of low coercive force (LCF) PMs, the associated excited loss is eliminated. Therefore, high efficiency operation within a wide range of speeds and loads can be achieved. The machine topology evolution, operating principle and the distinct features are addressed and highlighted. Then, the electromagnetic performance of ER-SF-HMMM is investigated and quantitatively compared with that of its IR counterpart, which confirm the theoretical analyses.