| Due to its simple structure,high efficiency,low price,and convenient maintenance,threephase squirrel cage asynchronous motors are widely used in many fields such as daily life,industry,agriculture,oil fields,and coal mines.Taking an actual project in a hydropower station as an example,when the motor equipment is in a harsh working environment or when the operating conditions are relatively complex,it is possible to avoid the interference caused by sensors and adopt speed sensorless monitoring for real-time monitoring of the motor speed.Therefore,it is of great significance to improve the speed estimation performance,robustness,and stability of motor speed sensorless control systems.Firstly,based on the mathematical model of three-phase asynchronous motors,the principle of coordinate transformation,and the basic theoretical knowledge of SVPWM pulse width modulation,the asynchronous motor itself,a multivariable and strongly coupled nonlinear system,is controlled through decoupling and order reduction.Then,based on the basic theoretical knowledge of model reference adaptive(MRAS),a speed sensorless vector control system model for asynchronous motors with rotor flux linkage was established in MATLAB-Simulink simulation software.Simulation experiments were conducted by changing the resistance value of the stator and rotor.The experimental results showed that the estimated speed identification ability of the motor without changing the resistance value of the stator and rotor was strong,and the estimated speed identification ability decreased after changing the resistance value.Starting from the practical engineering problems encountered in real-time speed monitoring of hydropower stations using speed sensorless control systems of rotor flux asynchronous motors,as the speed sensorless system of rotor flux asynchronous motors is designed and constructed based on the mathematical expressions of rotor flux voltage model and the mathematical expressions of rotor flux current model,When the resistance value of the motor changes with temperature and other factors,it will affect the accuracy of asynchronous motor speed estimation.In order to solve this problem,this paper studies and optimizes the speed sensorless control system of asynchronous motor based on rotor flux linkage,designs fuzzy control algorithm in the rotor flux adaptive structure and RC low-pass filter algorithm in the current rotor flux observation module,and conducts simulation research on the control system under different conditions of stator resistance value,rotor resistance value change and white noise interference,The simulation results show that the improved control system effectively reduces the error between actual speed and estimated speed compared to traditional control systems,and improves the accuracy of speed estimation.Due to the PI control method used in the traditional speed sensorless control system for rotor flux linkage asynchronous motors,such as speed regulators,flux regulators,and torque regulators,problems such as slow speed rise,serious overshoots,and poor load carrying capacity may occur during the operation and rotation of the system.The PI control of the speed regulator,the flux regulator,and the torque regulator in the control system is improved.The traditional PI control of the motor control system is optimized by the neural network algorithm in the speed regulator and use the second-order super-twisting sliding mode control algorithm in the flux regulator and the torque regulator.The simulation experiments are conducted on the motor control system under speed regulation and load conditions,respectively.The simulation results show that the improved control system is robust,Dynamic performance and its load carrying capacity have been significantly enhanced. |
