Research On LPV Control Method Of Permanent Magnet Synchronous Motor

In the permanent magnet synchronous motor(PMSM)control system,the rotational speed and position angle information of the motor are mainly obtained in real time by installing a sensor.However,the existence of the speed sensor leads to an increase in the cost of the motor drive system,a decrease in reliability,and an increase in volume.Due to the variability of the external environment,the monitoring accuracy of the speed sensor is also degraded.Therefore,in order to reduce the manufacturing and maintenance costs,the research on the sensorless vector control of permanent magnet synchronous motor has become the research trend of motor control in recent years.In this paper,combined with the linear parameter varying(LPV)control theory,the sensorless vector control strategy of permanent magnet synchronous motor is studied.Firstly,aiming at the problem of large chattering in the sliding mode observer of permanent magnet synchronous motor,a permanent magnet synchronous motor control method based on improved sliding mode observer is proposed.An adaptive sliding mode observer is designed based on the mathematical model of PMSM in stationary coordinate system,and the hyperbolic tangent tanh function is used as the switching function instead of the traditional symbol sgn function to weaken the sliding mode observation.The chattering phenomenon of the device and the normalization of the phase-locked link simplify the parameter processing of the phase-locked loop and improve the tracking accuracy of the position information.Compared with the improved adaptive sliding mode observer control strategy,the improved buffeting of the sliding mode observer is significantly weakened,and the position tracking accuracy is more accurate.Secondly,in order to avoid the chattering phenomenon that the sliding mode control can not be eliminated,and considering the parameter variation of the permanent magnet synchronous motor,a LPV control strategy of the permanent magnet synchronous motor is proposed.Firstly,the convex decomposition method is used to transform the permanent magnet synchronous motor model into a linear variable parameter system model with convex multi-surface structure.Then the linear matrix inequality(LMI)technique is used to design the vertices of the convex multi-surface structure.A robust output feedback controller that satisfies performance,selecting appropriate weight ratio synthesis controller parameters based on different vertex gains.Compared with the PI control strategy,this method solves the nonlinear modeling problem of permanent magnet synchronous motor.It has higher speed tracking accuracy and anti-load disturbance capability under variable load conditions.Finally,a backstepping control method of PMSM based on LPV state observer is proposed combined with LPV control theory.The method reconstructs the state of the stator current and the rotor angular speed in the rotating coordinate system by state estimation,and designs the backstepping controller with the estimated value to realize the sensorless control strategy of the permanent magnet synchronous motor.Firstly,according to the LPV motor model,the LPV state model equation of the observer is derived.Then,the stability condition of the closed-loop system is obtained on the basis of the Lyapunov stability theory.Then the singular value decomposition method is used to transform the Lyapunov stability condition into a linear matrix inequality condition.By solving the observer gain matrix at the apex of different convex shapes,synthesizing the feedback gain,designing the LPV observer,and finally obtaining the inverse based on the observation error between the observation value of the LPV rotation observer and the reference value,combined with the Lyapunov stability theory.Push the virtual control input of the control to achieve high-precision tracking control of the motor speed.Compared with the PI control strategy,the method has high control precision and fast response speed.