A unified winding function model for selecting high output torque in axial modular flux switching and flux reversal machines
摘要
As the novel axial modular stator permanent magnet machine (SPM), the toroidal winding is used to gain higher output torque in the axial modular permanent magnet flux switching (AM-FSPM) machine and axial modular flux reversal permanent magnet (AM-FRPM) machine. The winding function of the toroidal winding is a critical parameter that gains high output torque. A unified analytical expression for the winding function is proposed to simplify and improve the selection of candidate machines with optimal output torque for different Ps/Pr combinations. Then, the output torque capability of these machines can be compared under uniform analytical expressions. First, the topology of AM-FSPM and AM-FRPM machines is introduced. Meanwhile, the AM-FRPM machine is divided into two types based on the different PM magnetization methods. Then, the unified analytical expression of the air-gap flux density of three types of machines is investigated and verified by the FEA results. Furthermore, the model of the winding function is established based on the winding configuration of these machines. The unified analytical expression of the winding function can be ensured, and the critical coefficient Nswi of the winding function is summarized. Moreover, the back-EMF amplitude variation trend of the fundamental harmonic is calculated to predict the output torque variation trend of different Ps/Pr combinations. These two curves coincide well. Furthermore, the self- and mutual-inductance waveform of three machines is calculated by using the unified winding function. The analytical waveform is verified by the FEA. Finally, the 6-slot/8-pole AM-FSPM machine, 6-slot/8-pole AM-FRPM-M1 machine and 6-slot/7-pole AM-FRPM-M2 machine are chosen as design examples. The comprehensive electromagnetic characteristic is analyzed and compared, which verifies the effectiveness of the proposed analytical expression.