Study On Split Ratio And Eccentricity Of Two-Stage Halbach Array Permanent Magnet Machines

With the continuous mining of rare earth permanent magnet materials and the continuous improvement of the production process of permanent magnet(PM)machines.PM machines are increasingly superior to traditional electric excitation motors in terms of volume and power density,and are widely used in many fields.Therefore,it is of great theoretical significance and practical engineering value to study the structure and electromagnetic characteristics of PM machines.Polar arc ratio and split ratio also play a vital role in the optimizing the performance of PM machines.First,a novel segmented Halbach magnet array PM machine is presented,and the effects of split ratio and magnetization angle on the machine torque density are analyzed separately.Then,in order to achieve the maximum torque density of the machine,the optimal split ratio and magnetization angle are determined,and the electromagnetic characteristic parameters of the optimized parallel tooth permanent magnet motor are obtained by the Carter's coefficient method.Finally,the results obtained by the finite element method verify the effectiveness of the analytical model.The magnetic pole structure and magnetization mode have an important influence on the performance of PM machines.Firstly,a novel two-section bread-magnet PM machine is given.The mathematical model of the equivalent arc-shaped block magnet is established.The electromagnetic characteristic parameters of the fan-shaped slot PM machine are obtained by using accurate sub-domain analytical method.Secondly,for the maximum fundamental air gap flux density,the optimal magnetization angle is analyzed.Finally,the correctness of the analytical method is verified by a finite element method.A novel two-stage eccentric bread-type pole PM machine is given.The expression of air-gap flux density of the slotless PM machine is obtained by modeling of the magnet segmentation,and the electromagnetic parameters are derived by a modified Carter's coefficient for the parallel tooth PM machine.The performance of the machine is optimized by changing the magnetic pole eccentricity and the magnetization angle.The correctness of the analytical model is also verified by a finite element method.