Reverse Salient Pole Design of Interior Pole-changing Permanent Magnet Synchronous Motor

In order to prevent the demagnetization of low coercivity permanent magnets, the pole-changing permanent magnet synchronous motor usually adopts I-d=0 control strategy, which has the problems that the reluctance torque of the motor cannot be utilized and the torque density is low. In order to solve this problem, a new type of rotor reverse salient pole structure of pole-changing permanent magnet synchronous motor is proposed in this paper. Based on the comparative analysis of the magnetic field distribution characteristics of the motor under different pole numbers, the common d-axis and q-axis magnetic path under 8-pole and 4-pole are planned, and then the winding inductance L-d>L-q under two pole numbers is realized by setting bar and arc magnetic barriers and non-uniform reduction of air gap length. On this basis, the Taguchi method is used to set the parameters of the proposed structure, and the motor torque ripple is reduced under the premise of increasing the motor torque amplitude as much as possible under the 8-pole and 4-pole, and the optimal parameter combination of the proposed structure is determined. Through the FEA, it is verified that the motor can produce the maximum torque at the negative current angle before and after the pole change, so as to effectively utilize the reluctance torque, avoid the permanent magnet demagnetization and improve the torque density.