Research On Improvement Of Thrust Performance And Positioning Accuracy Of Ironless Core Permanent Magnet Linear Synchronous Motor

High-precision equipment such as high-precision machine tools usually use ironless linear motors as the power source,although the ironless linear motors have the advantages of small thrust fluctuation,good dynamic performance and high positioning accuracy.However,it still has certain disadvantages,such as its low thrust,and its thrust fluctuations still have room for further improvement.In the context of the application of high-precision machine tools,high-precision machining specifications also require iron-free linear motors to provide higher positioning accuracy,so the thrust fluctuations should be very small.In order to achieve the objectives achieved in this paper,the main work done in this paper is as follows:The mathematical model of the ironless core linear motor based on the equivalent magnetic potential method and the equivalent magnetization method is established.The analytical formula of the internal air gap magnetic field of the motor is derived.The solving algorithm which is closer to the finite element calculation result is selected.Based on this algorithm,the variation of the magnetic field harmonic content at the air gap of the motor when the ironless linear motor adopts different parameters is studied.The characteristics of different winding structures such as stacked and non-stacked are analyzed,and the thrust formula is derived.The distribution of thrust density of ironless linear motor is obtained according to the formula,and different windings are compared.The influenceof the structure on the thrust density of the motor is studied for the factors affecting the harmonic composition and content of the thrust of the motor.A new magnetic pole structure arrangement scheme is proposed for the air gap magnetic field waveform of the ironless core linear motor with conventional magnetic pole arrangement with small amplitude and insufficient sinusoidality.The simulation calculation of the ironless linear motor was made by Ansoft Maxwell software.The results show that the ironless linear motor with the new magnetic pole arrangement has larger thrust and less thrust fluctuation than the ironless linear motor with conventional magnetic pole arrangement.This new magnetic pole arrangement is also easy to implement in the process.According to the content analyzed in this paper,the general scheme and processing parameters of the ironless core linear motor design are given,and the performance and comparison of the permanent magnet materials used in the motor are made.The back yoke and the U-shaped groove in the linear motor were checked for strength,and the prototype was completed.The experimental method for repeating positioning accuracy test of ironless linear motor is given,and the experimental test is made on the experimental platform.The ironless linear motor of this new magnetic array developed in this paper has been experimentally tested and found to have superior positioning performance than the ironless linear motor under the conventional magnetic array,which has a very positive influence on the application in the machine tool.