Research On Fractional Order Sliding Mode Control Of Permanent Magnet Synchronous Motor

Because of its advantages of small volume,high efficiency,high power density and good reliability,PMSM is becoming more and more popular in wind power generation and rail transit,and sliding mode control has become an important choice for the motor control system because of its strong robustness and anti-interference ability.In order to better control the PMSM with high precision,the improvement of sliding mode control technology is an important research topic.Fractional order sliding mode control inherits the dual advantages of fractional calculus and sliding mode control.It has become an important branch of fractional order theory and provides a direction for improving the sliding mode control technology.In this paper,based on the speed and position tracking control of permanent magnet synchronous motor,a sliding mode controller and a sliding mode observer are designed by the fractional calculus theory,and the related problems of the fractional order sliding mode control theory are analyzed.In the aspect of sliding mode controller,a fractional order nonsingular terminal sliding mode control law is proposed to solve the problem that the singular and the convergence time of the traditional terminal sliding mode is not up to the optimal.In order to improve the ability to suppress the load disturbance of PMSM,a fractional order nonsingular terminal sliding speed controller with a load torque observation value is designed by using the fractional integral sliding surface,and the load torque values are obtained by using the model reference adaptive sliding mode observer.In order to improve the precision of rotor position control of permanent magnet synchronous motor,a fractional order PI?D sliding mode surface is adopted to design a fractional order adaptive sliding mode position tracking controller,in which the parameters of the sliding mode control are adjusted by the adaptive law with a threshold.Compared with the traditional sliding mode and adaptive sliding mode,the response speed of the position tracking is speeded up,and the error is small.On the basis of the traditional sliding mode approach law,the fractional order differential operator is introduced to analyze the structural characteristics and control performance of the fractional order reaching law.It is applied to the speed controller of the permanent magnet synchronous motor,and the influence of the order of the fractional order reaching law and fractional order sliding surface on the dynamic and static performance is analyzed.In addition,on the basis of the traditional sliding mode observer,the fractional calculus algorithm is introduced based on the traditional sliding mode observer.So a fractional order sliding mode observer with small chattering and high precision is proposed,and its stability is proved,and the reason that the fractional order sliding mode observer is smaller than the traditional sliding mode observer is analyzed,and then the fractional phase locked loop is used to extract the rotor and the position.This method is simple and reliable,and has good dynamic and static observation precision.In this design idea,the fractional order approach law is applied to the sliding mode observer,which also achieves good results.