Thrust Fluctuation Analysis And Structural Optimization Design Of Permanent Magnet Linear Synchronous Motor

Permanent Magnet Linear Synchronous Machine(PMLSM),which has the advantages of both permanent magnet and linear motors: high thrust,high precision,high speed,high acceleration,high efficiency,etc.has been widely used in highprecision CNC machine tools,Semiconductor processing equipment,high-speed logistics,and other industries.This article focuses on the analysis and suppression of PMLSM thrust fluctuations as follow:(1)Based on the equivalent magnetization method,an analytical model of the magnetic field of a flat plate with iron core,short primary and long secondary PMLSM is established.The air gap magnetic field with core and slotless PMLSM was obtained by analytical calculation,and compared with the finite element simulation results,the correctness of the analytical formula of the slotless PMLSM air gap magnetic field was verified.(2)Based on the equivalent magnetic circuit,an auxiliary pole design method to suppress the longitudinal edge effect of PMLSM is proposed through the virtual displacement energy method,and the analytical expression of the optimal auxiliary pole structure and position is derived.Ansys Ansoft-Maxwell software was used to carry out finite element calculations on the model.By comparing the analytical values of different slot poles with the PMLSM auxiliary pole restraining force and the finite element simulation values,the correctness of the mathematical model and the effectiveness of the auxiliary pole structure were proved.Secondly,according to the same PMLSM model,different methods of restraining the no-load positioning force of PMLSM are compared,and the advantages and limitations of various methods are compared.(3)According to the PLMSM electromagnetic thrust characteristics,analyze the causes of PLMSM load thrust fluctuations,design the winding form with the least ripple disturbance;obtain the dynamic characteristics of different concentrated winding load thrust fluctuations,and improve the tooth structure to suppress the dynamic current.The change of thrust fluctuation,combined with the auxiliary pole calculated by the design,greatly reduces the amplitude of load thrust fluctuation.(4)Based on the Maxwell tensor method,the PLMSM normal force wave is analyzed and calculated,and the relationship between the normal force fluctuation and the thrust fluctuation is obtained.The finite element calculation proves that the trapezoidal tooth has auxiliary pole PMLSM can effectively suppress the thrust fluctuation and normal Force fluctuations.Using Ansys-Workbench to calculate the PLSSM primary core vibration mode and natural frequency of straight teeth without auxiliary poles and trapezoidal teeth with auxiliary poles,the normal force wave is loaded into the harmonic response analysis as the PMLSM excitation force,and the PMLSM normal displacement is obtained Frequency response graph,and comparative analysis.