Cogging Torque Reduction of Axial Flux Permanent Magnet Synchronous Motors For Gravity Energy Storage System

The axial flux permanent magnet synchronous motor (AFPMSM) has the characteristics of simple structure, small volume, high torque density, and high efficiency. Thus, it is suitable for the gravity energy storage systems. But the inherent cogging torque problem may cause mechanical vibration and noise, which in turn affects the performance of the total system. In order to effectively suppress the adverse effects of cogging torque, both theoretical analysis and finite element simulation is done to optimize the cogging torque of AFPMSM in this paper. Firstly, the theoretical analysis for the cogging torque of surface mounted type AFPMSM is elaborated; Afterwards, the 3D motor model is reduced to a 2D equivalent model using the equivalent simplification method; Finally, taking a 10 pole 12 slot double stator single rotor surface mounted AFPMSM as an example, some main parameters were selected for simulation analysis and comparison, including stator slot pole shoes, stator slot misalignment, permanent magnet pole arc coefficient, and permanent magnet shape. Finally, a minimum cogging torque model was obtained.