Research On PMSM Sensorless Speed Control

In recent years,sensorless control of Permanent Magnet Synchronous Motor(PMSM),as an important method that is expected to improve the reliability and fault tolerance of the motor,has attracted researcher’s attention.Actual PMSM is affected by uncertain disturbance factors such as time-varying system parameters and load perturbation.Existing sensorless control methods still have shortcomings such as low rotor state(rotation speed and position)observation accuracy and robustness,resulting in the inability to obtain excellent PMSM sensorless speed control performance.In this paper,from the perspective of improving the anti-interference ability of sensorless control system,and exploring the rotor estimation algorithm with high estimation accuracy and strong robustness,the following two innovative research and work are mainly completed as follow:1.Research on PMSM sensorless speed auto disturbance rejection control based on sliding mode observerIn this part of work an improved sliding mode observer based on the PMSM mathematical model in the α-β coordinate system is designed to effectively estimate the PMSM rotor state,and a phase-locked loop technology with good tracking ability is used to extract the rotor state information,overcoming the shortage of estimation delay caused by the use of inverse tangent function filter extraction of traditional sliding mode observers,which leads to the decline of sensorless control performance;According to the resistance parameter variation disturbance of motor system,estimation error of rotor state and load disturbance,by using the state equation of PMSM in d-q rotating coordinate system,the linear active disturbance rejection controllers(LADRC)for current loop and speed loop were designed respectively.For the purpose of eliminating the influence of internal disturbance of the system on current loop,a linear expansion state observer is designed to observe and estimate the internal disturbance of the system,and a control rule of error linear feedback,in accordance with that of speed loop,based on PD structure is designed to compensates for observation disturbance.The design idea of the speed loop is the same as the current loop,the influence of load and estimation error on the performance of sensorless speed control are estimated by the linear expansion state observer and the error linear feedback control law of the PD structure.In order to improve the performance and robustness of PMSM sensorless speed control,double closed-loop auto disturbance rejection control is used to suppress the influence of disturbance and rotor state estimation error on sensorless control performance.2.Research on PMSM sensorless speed control based on fractional sliding mode observerMost existing PMSM rotor state estimation algorithms are of integer order.In recent years,in order to obtain high-performance PMSM sensorless control,people have begun to try to use fractional order theory for PMSM rotor state estimation and detection,but there are few relevant research reports,indicating that research in this area is still in its infancy.This paper proposes a PMSM sensorless speed control method based on fractional order sliding mode observer.This method starts from the PMSM state mathematical model in theα-β coordinate system,defining a fractional sliding mode function with the stator current observation error as a variable,combining the stability theory to design the control law of the fractional sliding mode observer,and using the frequency domain theoretically design the fractional order parameters;Rotor state extraction method based on the fractional order phase-locked loop is designed,which can not only overcome the problems of low-pass filtering and phase compensation required by the traditional arc tangent function extraction,but also further improv estimating accuracy of rotor speed and position.The simulation comparison results verify the effectiveness and advanced nature of the work.The research results provide useful theories and methods for formulating a high-performance PMSM sensorless speed control system,which has good theoretical and engineering application significance.