Modeling And Magnetic Field Analysis Of Novel Halbach Array Permanent Magnet Machines

With the continuous in-depth research of new permanent magnet materials and the vigorous development of power electronic technology in recent years.The advantages of PM machines have become more obvious,such as high efficiency,high power density,small size and high reliability,and make their application prospects broader.This article mainly studies the structure design of surface-mounted PM machines.Through the layered and segmented optimization design of Halbach array magnet,the electromagnetic performance of PM machines are more excellent,which has certain theoretical value and engineering practical significance.Aiming at the Halbach array permanent magnet,a surface-mounted PM machine with odd-/even-segmented magnet has been proposed.Analytical modeling and analysis of the Halbach array machines are carried out,and the pole ratio and magnetization angle of each segmented magnet was calculated,and the optimal solutions of each parameter were obtained.Subsequently,the Carter’s coefficient method is used to solve the analytical expressions of the air gap flux density,induced electromotive force and electromagnetic torque under the stator slot structure with no tooth tip and parallel teeth.Then,the influence of the percentage of the segmented magnets and the magnetization angle on the electromagnetic performance are analyzed.Finally,the finite element method is used to verify the PM machine model.Two surface-mounted PM machines with dual-layer Halbach array permanent magnet are proposed.The permanent magnets are respectively composed of two layer segmented magnets with the same structure.A permanent magnet machine model for these two structures is established,and the optimal middle permanent magnet ratio and the magnetization angle of the permanent magnets of the inner and outer layers are obtained.And the Carter’s coefficient method is used to solve the electromagnetic parameters under the structure of equal-thickness tooth tip and parallel teeth.The results show that the PM machine with the dual-layer magnet structure has better electromagnetic performance than the corresponding single-layer one.Finally,the analytical model was verified by finite element analysis method.Regarding the magnet structure proposed in Chapter 3,for the permanent magnet structure whose pole arc ratio is not equal to 1.The outer and inner layers of the magnet are divided unevenly,so that the pole arc ratio of inner or outer layer magnet is1.In this way,two PM machines with dual-layer unequal pole arc ratio magnet are obtained.Analytical modeling and parameter optimization analysis were also carried out on it.Through the comparison results,it is found that the PM machines whose outer magnet pole arc ratio equal to 1 has the optimization effect on the air gap magnetic density and the induced electromotive force and the average electromagnetic torque,but the harmonics of various parameters both have increased;and the PM machines whose the inner magnet pole arc ratio equal to 1 is optimized in terms of harmonic performance.For electromagnetic torque,the results show that PM machines with the more outer permanent magnet can obtain a greater electromagnetic torque;while a motor with the more inner permanent magnet can reduce its torque ripple.Finally,the finite element method was used for verification.