Research On Permanent Magnet Linear Synchronous Motor With Polygon Combination

Permanent magnet linear synchronous motor with polygon combination（PCPMLSM）has the advantages of small normal force and modules combination in the axial direction,which has high application prospects in the linear drive field.Compared with tubular linear motor,PCPMLSM achieves circumferential lamination and reduces eddy current losses.Compared with flat linear motor,the combined structure solves the problems of complex manufacturing and hard maintenance of large volume in the field of low speed.However,broken core and polygon structure lead to large thrust ripple,which seriously affects the smooth operation and location accuracy of motors.Therefore,this thesis focuses on the structural characteristics of PCPMLSM and the optimization of its thrust quality.Firstly,the structural characteristics of PCPMLSM are analyzed.Primary core laminations are in the circumferential direction,and primary winding is polygonal structure.One module can be combined in the axial direction to form a multi-module structure.According to the structural characteristics of PCPMLSM,the design method is summarized.In order to improve the utilization rate of winding,PCPMLSM uses fractional slot concentrated winding.Different pole-slot combinations are studied.Magnetomotive force generated by winding is analyzed.The back EMF waveform distortion rate,detent force and thrust ripple are compared,and the final pole-slot combination is determined.Then,the end force of PCPMLSM is weakened from the structure parameters.The nonperiodic rule of single end force caused by asymmetry of the end flux is studied.On this basis,the method of reducing the end force by combining the optimization of the primary core length and dislocation of the end teeth with unequal width on each side is used to weaken the first and second harmonics with higher amplitude in the end force.The proper core length and proper dislocation position are obtained by regression analysis and formula method,respectively.Next,the detent force is weakened by the modular dislocation combined structure,Based on the principle of invariant back EMF,the winding arrangement of the dislocation module is reconstructed to reduce the thrust ripple without affecting the average thrust.This thesis focuses on the analysis of three two-module dislocation structures and five three-module dislocation structures.Finally,the thrust quality of PCPMLSM is optimized by establishing the Kriging surrogate model.Two sets of orthogonal test tables are established,combined with signal to noise ratio analysis and variance analysis to select sensitive structural parameters that have a significant influence on thrust quality.The Kriging model is established by taking the test data uniformly in the multi-dimensional space through the maximin Latin hypercube sampling.Combined with NSGA-Ⅱ optimization algorithm,multi-objective optimization of average thrust and thrust ripple is achieved.The calculation results show that the thrust quality has been improved obviously.