Research On Improved Sliding Mode Speed Control Strategy Of Permanent Magnet Synchronous Motor Based On Disturbance Compensatio

Permanent magnet synchronous motor(PMSM)has attracted wide attention in industrial applications due to its high efficiency,high power density and high reliability.The motor vector control based on PI control technology has become the mainstream control method of the motor due to its simple algorithm and easy engineering implementation.However,with the continuous improvement of the control performance requirements of the motor drive system,the traditional PI control method has been unable to meet the system requirements in terms of control accuracy,response speed and anti-interference ability.In the actual PMSM control system,various uncertainties such as parameter perturbation,unmodeled dynamics and external interference will affect the control performance of the system.Based on the above problems,this paper takes PMSM drive system as the research object,and aims to improve the dynamic performance,steady-state performance and anti-disturbance performance of the system.A PMSM control strategy based on improved sliding mode is proposed,and combined with model-free control,iterative learning control,disturbance compensation control and other technologies to achieve high-performance and stable control of PMSM drive system.The main contents of this paper are as follows :(1)In order to improve the speed tracking performance and robustness of PMSM and reduce the dependence of the designed controller on the dynamic model of the motor,a model-free sliding mode control strategy of PMSM based on disturbance observer is proposed,and a model-free sliding mode speed controller and a current controller are designed respectively.Firstly,a ultra-local model of PMSM system without considering motor parameters is established.Then,a model-free sliding mode speed controller and a current controller are designed based on the improved sliding mode reaching law.In addition,aiming at the problems of external load disturbance and parameter uncertainty in the permanent magnet synchronous motor control system,a nonlinear disturbance observer and an extended state observer are designed to estimate the unknown disturbance of the system and use it for feedforward compensation to improve the robustness of the system.(2)The above designed controller still adopts double closed-loop cascade control structure.However,with the continuous development of power electronics technology and computer control technology,the control cycle difference between the speed loop and the current loop gradually decreases.Therefore,the permanent magnet synchronous motor based on non-cascade structure can obtain better control performance.The advantages of non-cascade control are simple control structure and direct speed control.In this paper,a speed-current non-cascade control strategy based on improved model-free sliding mode control is proposed.Firstly,a model-free sliding mode speed controller is designed based on the ultra-local model of the permanent magnet synchronous motor system.The controller uses the speed-current non-cascade sliding mode control strategy to replace the traditional speed-current cascade control.The speed and current of the permanent magnet synchronous motor are adjusted in one loop,which simplifies the control system structure.Then,a dual disturbance observer is designed to estimate the matched disturbance and mismatched disturbance in the system,which is used as the feedforward compensation of the speed controller to improve the robustness of the system.(3)It is considered that although model-free control can eliminate the influence of unmodeled dynamics to a certain extent,it is related to the estimation accuracy of the unknown part of the system hyperlocal model.Therefore,a single-loop control strategy of permanent magnet synchronous motor based on integral sliding mode control and iterative learning method is proposed.The controller still adopts the noncascade sliding mode control strategy instead of the traditional speed-current cascade control.By introducing the iterative learning control,the torque ripple caused by the unmodeled dynamics of the system is effectively suppressed,and the steady-state control accuracy is improved.In addition,aiming at the external load disturbance and parameter uncertainty of the system,a dual disturbance observer is designed to estimate the system disturbance and improve the robustness of the system.Finally,for the above three control strategies,the experimental verification is completed through the experimental platform of the permanent magnet synchronous motor speed control system,and it is compared with the PI algorithm and the traditional control strategy.The experimental results show that the three control strategies proposed in this paper have good dynamic performance,anti-interference ability and steady-state control accuracy,and realize the high-performance and stable control of the permanent magnet synchronous motor drive system.