Design And Thrust Ripple Suppress Of Permanent Magnet Linear Synchronous Motor

As the best choice of linear servo system, permanent magnet linear synchronous motor(PMLSM) has many advantages including simple structure, small electrical time constant,rapid response, high thrust density. But the cogging force, end effect force, friction force andother unfavorable factors cause the thrust fluctuation, which seriously affect the controlprecision and stability of the PMLSM servo system, limit its application in high precisionmachining field. The thesis focused on the optimal design of PMLSM, and then based on themodularization concept, restructured the unit of the motor, and analyzed the combination ofcore primary PMLSM to further restrain thrust ripple.Firstly, the main structure of the11poles12slots PMLSM was determined and analyzed,the fractional slot and concentrated winding were selected as the design plan. The distributionof cogging force with different slot structures and the distribution of end effect force withdifferent core length and end chamfering were analyzed to obtain the method to suppressdetent force and thrust fluctuation.Secondly, the physical model of PMLSM was established based on Ansoft finite elementmethod(FEM), the genetic algorithm(GA) module of Ansoft was used to combine geneticalgorithm(GA) with FEM. Then the analysis method aiming at multivariable cogging structureand end structure optimization was used to suppress detent force and thrust fluctuation. Theanalysis results show that the multivariable optimization method can compensate for theshortage of single variable optimization, coordinate the relationship between all the specificsizes and provide reliable solutions to inhibit thrust fluctuation of PMLSM.Thirdly, the method of combined core primary was put forward based on the idea of thesegmented structure. Through the analysis of combined core primary, it was found thatPMLSM had symmetrical cyclic characteristics similar to rotary motor, and the detent forcebetween two adjacent modules has certain phase difference, the detent force fluctuation causedby the end effect can be effectively reduced by the optimization of the harmonic components.The maximum thrust average value was obtained by the rational allocation of section windingcurrent initial phase.Finally, three sections combined core primary PMLSM were analyzed by FEM, the optimum distances between the sections obtained by the analytical method and the FEManalysis results were compared to validate the correctness. the FEM results show that themethod of combined core primary can effectively inhibit the detent force, normal force andthrust fluctuation, then the method was promoted to provide a new direction for PMLSMdesign.