Research On Application Of Sliding Mode Algorithm In PMSM Vector Control

Permanent magnet synchronous motor(PMSM),as a widely used power output device,has many advantages such as high power density,small size,and low noise.However,it is strongly coupled and non-linear,and traditional vector control methods are poor in robustness.On the other hand,accurate rotor position information is the key to achieve the traditional vector control.In some special applications,the presence of position sensors will reduce the stability of the system.Position sensorless vector control technology is a good alternative.The sliding mode algorithm has a wide range of applications in the PMSM vector control system.This paper takes PMSM as the research object,and studies the application of sliding mode algorithm in PMSM speed control and sliding mode observer in position sensorless control.First,aiming at the shortcomings of the traditional PI speed controller in double PI closed-loop PMSM vector control system,which is sensitive to parameter changes and poor robustness,a new sliding mode reaching law is proposed,and a speed sliding mode controller(SMC)is designed for PMSM vector control.There is a convergence problem of the reaching law when the system has bounded disturbance.Then a new type of extended sliding mode disturbance observer(ESMDOB)is designed to observe the disturbance and feed forward compensation to the speed SMC to ensure the convergence of the controller and eliminate the influence caused by the disturbance.Secondly,the application of the sliding mode observer(SMO)in the position sensorless PMSM vector control system is studied.For the first-order sliding mode observer(FOSMO)has chattering problem and phase delay caused by low-pass filter when estimated rotor position and speed of PMSM.Then a super twisting algorithm second-order sliding mode observer(STASSMO)is proposed.The observer eliminates the low-pass filter,suppresses sliding mode chattering,and improves the observation accuracy and has better control results.Thirdly,in view of the problem that there is no valid method to decide the sliding mode gain of the STASSMO,and the fixed gain has poor robustness when estimating the position and speed of the PMSM rotor,a fuzzy super-twisting algorithm secondorder sliding mode observer(FSTASSMO)is proposed under relevant stable conditions.The fuzzy controller achieves self-tuning of sliding mode gain and reduces the estimation error of position and speed,widens the effective observation range,and enhances the robustness of PMSM position sensorless vector control system.Finally,in order to further improve the control accuracy and robustness of the PMSM position sensorless vector control system,a compound sliding mode control strategy is proposed.Using the speed SMC of the new reaching law to compound FSTASSMO,and the system can obtain better control results.All the proposed algorithms have built a control system on the Matlab/Simulink platform,conducted simulation tests and performance comparisons.The results show that the proposed algorithms are feasible,effective and have certain advantages.