Research On Sliding Mode Buffeting Of Permanent Magnet Synchronous Motor Servo System

PMSM is widely used in high-end milling machine tools due to its high power density and small volume.At present,PMSM for high-end milling machine tools generally adopts PI control,which is difficult to ensure the high performance control requirements when the internal parameters of the motor fluctuate and the external load is disturbed.The sliding mode control method has the advantages of fast response speed,good robustness and simple implementation,but there is chattering in the sliding mode control.Therefore,this paper focuses on the improved exponential approach law and the fast power approach law,and on the basis of the improved fast power approach law,introduces the feedforward control method to reduce the chattering problem in the sliding mode control,and applies the improved sliding mode control algorithm to the PMSM id=0 vector control system.Specifically includes the following contents:Firstly,the mathematical model of permanent magnet synchronous motor in d-q coordinate system is established.According to the theory of automatic control and PI control theory and combined with permanent magnet synchronous motor mathematical model is established in the transfer function of PI controller,PI controller parameters setting and deduces the equation,through the analysis of the transfer function of PI controller and parameter setting equation is pointed out that the PI control method in motor internal defects control parameters fluctuation occurs,built in the MATLAB/SIMULINK simulation model for the simulation supporting the rationality of the proposed ideas.Secondly,analyzes in detail the sliding chattering of several kinds of reaching law method,exponential reaching law is the main research in the application of sliding mode control of permanent magnet synchronous motor,aiming at the existence of exponential reaching law method in the approach speed and weaken the chattering of the coupling problem,this paper proposes a modified exponential reaching law,the reaching law approach speed and restrain chattering decoupling,not only reducing the rate of the traditional exponential reaching law the chattering at the same time enhance the response speed of the traditional exponential reaching law,id = 0 in permanent magnet synchronous motor vector control system based on improved exponential reaching law is introduced into the speed of integral sliding mode controller,the simulation results show that,The sliding mode control method based on improved exponential approach law reduces the chattering rate of the motor control system from 7.69% to 2.4%,and improves the response speed of the motor control system.Then,studies the commonly used to weaken the chattering in the sliding mode control another way fast exponential reaching law control performance,against the slow convergence speed,chattering,poor ability to resist external disturbance,this paper proposes a specific double exponential reaching law of sliding mode control method,weakens the sliding mode chattering at the same time improve the converge speed.But the interior of the motor parameter fluctuations and external load disturbance,the double exponential reaching law unable to converge to the equilibrium point and lost the ability to resist disturbance,therefore the introduction of feedforward control in the motor control system,the load value feedforward compensation to the controller,through the feedforward control to solve the double exponential reaching law can't converge to equilibrium point.The introduction of feedforward control not only improves the anti-disturbance ability of the double power approach law,but also weakens the chattering of the system.The simulation results show that the hybrid control strategy based on double power approach law and feedforward control improves the response speed and anti-disturbance ability of PMSM control system,and reduces system chattering.Finally,TMS320F28335 as main control chip of the controller and the drive to build permanent magnet synchronous motor control system,with the help of Israel M.E.A company produces the RDS test system for motor load machine load,has set up a permanent magnet synchronous motor for the whole sliding mode control experiment system,further verify the validity and rationality of the proposed control algorithm.