Design Of Permanent Magnet Linear Synchronous Motor And Research On End Magnetic Resistance Weakening

In this paper,I choose the permanent magnet synchronous linear motor(PMLSM)as the research objection used in CNC machine tools is studied for the motor design scheme and reduction of magnetic resistance at the motor end.To address the problem of thrust fluctuation during the operation of a 6-slot,7-pole single-sided flat type permanent magnet synchronous linear motor,which leads to poor machining accuracy,I suggest using the method of combining V-pole and Magnet-Staggered Method is proposed;and a single-stage convex stepped auxiliary tooth structure is proposed for the correlation between the width and position of the auxiliary tooth and the fluctuation of thrust.(1)Establish a model of a permanent magnet synchronous linear motor using basic parameters.Based on the design formula and process of rotating motor;the formula of rotating motor is converted into that of linear motor to calculate the main dimensional parameters,no-load operating point of permanent magnet and resistance reactance of winding,We shall select the suitable air gap width and slot type;finally,the per-unit system is used to iterate the previously calculated parameters to find more accurate dimensions.(2)Three analytical models of the effect of operating state on thrust fluctuation under motor end effect are established: static analytical model of transverse end effect,and dynamic and static analytical model of longitudinal end.The magnetic density distribution in the longitudinal end region of the permanent magnet synchronous linear motor is obtained from the static model analysis,where the longitudinal static analytical model established by Schwarz-Christoffel Transformation can be acquired for the dynamics in the longitudinal end effect after considering the end fictitious boundary;after analyzing the longitudinal end of the motor,the static analysis model under the transverse end effect is further analyzed,and the correlation between the external overhang length and the transverse end magnetic field is verified by simulation.(3)I have also studied the stucture optimization of permanent magnets under dynamic analysis of the longitudinal end effect of a permanent magnet synchronous linear motor.The influence of the longitudinal end effect on the motor thrust is introduced,and the Schwarz-Christoffel Transformation is used to derive a uniform magnetic field at the motor end,and the motor thrust expression is further derived from the uniform motor end field.The number of harmonics causing thrust fluctuations is derived from the function in the expression.By combining the motor pole structure with the Magnet-Staggered Method,the V-shaped three-stage pole structure is proposed to reduce the motor thrust fluctuation.(4)Based on the theoretical derivation,I have basically studied the end structure of the motor.The effects of the static analysis model of lateral end effect and the dynamic analysis model of longitudinal end effect on different end structures of the motor are introduced;the end magnetic resistance of PMLSM is analyzed based on the lateral force method,and the expression of the width of the auxiliary tooth is derived when the end magnetic resistance of the motor reaches a minimal value in a region;a single-stage convex-stepped auxiliary tooth structure of the PMLSM is proposed by combining the auxiliary tooth with the Magnet-Staggered Method;by comparing the simulation results of the improved end structure using ANSOFT,we could see that the single-stage convex stepped auxiliary tooth structure can effectively suppress the thrust fluctuation and improve the stability of the motor.(5)Experimental verification of four different structures of permanent magnets demonstrates the feasibility of the optimization method combining magnetic pole misalignment with different pole structures.