Design And Analysis Of Partitoned-primary Modular Linear Permanent Magent Vernier Machine

With the rapid development of urban rail transit,it is urgent to study the related technologies of rail transit traction systems.Linear machines directly generate electromagnetic force through the relative motion of traveling wave magnetic field to drive the vehicle,with good starting and accelerating performance.Direct drive systems require the machine itself to have high thrust force density characteristics.However,the thrust force density of traditional linear permanent magnet machine is limited,making it difficult to meet development needs.Introducing the magnetic field modulation mechanism into the linear permanent magnet machine can effectively improve the thrust force density.However,the permanent magnets and armature windings of the traditional structure linear permanent magnet vernier machine are placed on the primary side,making it difficult to further improve the thrust force density.This paper proposes a partitioned-primary modular linear permanent magnet vernier(PP-MLPMV)machine,which effectively solves the problem of primary spatial conflicts and skillfully incorporates the modular primary structural design.On the one hand,it can significantly improve the thrust force density,and on the other hand,it can improve the fault-tolerant capability of the machine.In addition,based on the magnetic field modulation theory,this paper explores the inherent mechanism that the partitioned primary can improve the performance of linear permanent magnet vernier machine from the perspective of harmonics.The main research content of this article is divided into the following aspects:1.The topological structure characteristics of the linear permanent magnet vernier machine are analyzed.Based on thrust force and iron loss characteristics,the optimal slot pole coordination and winding connection mode are selected.The mathematical models of magnetomotive force and magnetic conductivity for the machine are constructed.The expressions of magnetomotive force and permeance,as well as corresponding Fourier expressions,are derived.The formula calculation results are compared with the finite element simulation results,verifying the correctness of the analytical results and revealing the multi harmonic working principle of the linear permanent magnet vernier machine.2.The adoption of the modular primary design scheme enhances the overall fault-tolerant performance of the machine.The similarities and differences between the PP-MLPMV machine and the traditional structure machine are compared.Based on the theory of magnetic field modulation,the influence of different magnetomotive forces and permeances on the modulation effect of the machine are elucidated,and the distribution characteristics of harmonics are summarized.The principle of enhancing the magnetic field modulation effect by the partitioned primary structure and the contribution of each order harmonic to the fundamental back electromotive are revealed.3.From the theoretical level,the fundamental reasons for the performance changes of the PP-MLPMV machine are explored.The electromagnetic performances of two linear permanent magnet vernier machines are comprehensively analyzed and compared by the finite element method.The results show that the thrust force density of the PP-MLPMV machine can be increased by 32.3% without increasing the electromagnetic load.4.A prototype of the linear permanent magnet vernier machine are processed and manufactured,and the prototype related experimental testing platform are built based on existing laboratory equipment.The correctness of theoretical analysis and finite element simulation results are verified through experimental testing.