Research on cogging torque characteristics of permanent magnet synchronous machines with the same number of poles and slots

This paper presents a new permanent magnet synchronous machine with the same number of poles and slots by combining two unit machines. The machine is designed by the magnetomotive force star diagram, and the performance of the machine is demonstrated by finite element simulation. Since the number of poles of the two unit machines is different, the number of periods of the machine cogging torque is solved based on the energy method. In addition, all slots are divided into four parts according to the size of the slots, and the analytical model of cogging torque is established by the superposition technique. Based on the analytical model, the combination of the unit machine and the slot opening width are optimized to further reduce the cogging torque. Finite element simulations were used to verify the validity of the theoretical derivation and to further validate the lower cogging torque of the permanent magnet machine with same number of poles and slots when the slot opening width is the same.