Model Identification And Control For High-precision Linear Motor

Permanent magnetic synchronous linear motor(PMLSM) can provide straight force directly. Its linear structure makes it escape from centrifugal force and all intermediate transmission mechanism can be canceled between rotation motor and workbench. Therefore, in the case of demanding straight linear driver, compared with a rotary motor, linear motor control system can achieve greater speed and acceleration and position accuracy. These characteristics make linear motor has wide application in the field of military, transportation, industry and so on, especially get remarkable achievements in the CNC machine. However, some shortages of linear motor limit the performance, such as friction and cogging force. Therefore, it’s significant to analyze the reasons of limiting linear motor performances and how to solve them.Based on the analysis of the electromagnetic field, this paper studied the causes of interference and their models, which include friction and ripple force, and established dynamic model of PMLSM, then identified important parameters in the model, finally designed controller for speed loop and position loop.Firstly, in the view of electromagnetic this paper discussed the occurrence reasons of thrust ripple, and set up the air-gap magnetic field model through EMC,and established geometric model of PMLSM and got distribution curve through the finite element analysis method. Then analyzed the model of friction and influence of load force,and deduced thrust equation through coordinate transformation. Therefore,established a complete dynamic model of PMLSM.Secondly, identified important parameters in PMLSM model with regression memory RLC. For thrust ripple and friction are nonlinear, according to data obtained from finite element analysis simulation, identified their main frequency with spectrum analysis. Finally, applied PMLSM to control system,and studied control strategies, then designed PI controller for speed loop and PID controller for position loop. To the problem of PID parameters tuning, engineering design method and genetic method were adopted to modify PID parameters.On the basis of theoretical analysis, established PMLSM control model and programmed M-file in MATLAB,through ANSOFT software established geometric model to simulate PMLSM’s electromagnetic field, model recognition and systemcontrolling process. And verified the above theory, identification algorithm and control method.