Multiple Objective Optimization Design Research Of Permanent Magnet Synchronous Linear Motor Based On Taguchi Fuzzy Inference Method

This paper researches the Permanent magnet synchronous linear motor(PMSLM)which is applied in the micro second laser engraving machine.This paper aims to the thrust ripple problem and proposes Taguchi fuzzy inference optimization method from the ontology structure,achieving the multiple design optimization which can promote the PMSLM performances.Double secondary hollow PMSLM has the advantages of large thrust density,low loss and fast response due to the direct drive mode,simple structure,no slot effect and core breaking,it can reach large stroke in high speed and microsecond dynamic accuracy,it was wildly used in high speed and high precision CNC machine tools.Because of its disadvantage and the thrust problem,it is easy to cause the motor vibration and noise,decrease the position accuracy which can seriously influence the operation problem and increase the scratch with roughness of the workpiece during machining.It needs to optimize the structure parameters from the ontology structure,and determine a group of the best structure parameters which can satisfy the average thrust remaining,the lowest thrust ripple and lowest THD.So the motor performances will be promoted and improve the quality of finished products.Traditional methods for PMSLM design optimization can be concluded as follows:One is the method based on equivalent magnetizing current or equivalent magnetization.In the ideal assumptions,analyze the PMSLM electromagnetic mechanism,then deducing the analytical expression of motor performances,finally using the intelligent algorithm to optimize and solve the best combination of structure parameters.This method has a disadvantage of low accuracy due to the many assumed conditions and the local optimum limitation of algorithm.Another method is Finite Element Analysis(FEA)method,from the hundreds and thousands of FEA modeling calculation and selecting one best combination of motor structure parameters.But this method has a low efficiency,it is a waste of time,it can't satisfy the requirement of the huge data of motor multiple optimization design.The other method named Taguchi optimization method is the improvement of FEA,from the design of experiment it can get the best result by using the least number of FEA experiment.But this method is more suitable for single goal optimization,by the number increasing of optimization goals,it can't solve the conflict and restriction of multiple goals.So,all above mentioned methods have some problems when applying in the multiple design optimization of PMSLM.This paper design one kind of PMSLM according to the performance requirement of microsecond laser engraving machine.Based on the design foundation,from the equivalent magnetization method,analyzing the motor performances and determine the main structure parameters which can influence the motor performances.According to the value range space of structure parameter,building the FEM model of PMSLM and verify the validity,analyzing the advantages and disadvantages of the application in PMSLM design optimization.By introducing the Taguchi method,it can use the least number of FEA experiment to obtain the best experiment result by orthogonal experimental design,and can promote the calculation efficiency by 98.43%.By analysis,this method is more suitable for single goal optimization,it is not suitable for multiple objective optimization.By detailed comparison of the above-mentioned methods,this paper introduced fuzzy inference method to improve the traditional Taguchi method,and introduce the Mandami fuzzy inference engine and Gaussian membership function to fuzzification,adapting the gravity method to deffuzzification.Finally,we can obtain a multiple performance characteristic index(MPCI),which can translate two performance indexes to single performance index and solve the conflict of multiple goals and achieve the multiple objective optimization of PMSLM.From the comparison of simulation experiment and prototype experiment,the validity and progressiveness were verified,it can provide a new method for the PMSLM multiple objective optimization design of reverse refinement.