Random Adaptive Fuzzy Control Of Asynchronous Motor Based On Command Filtering

Because of its simple structure,small size and convenient maintenance,induction motors(IMs)are widely used in many situations,such as speed regulation,transmission and so on.However,due to the limitations of time-varying motor parameters,strong coupling and non-linear input,the accurate control of induction motor becomes a very challenging issue.Although many control strategies for induction motors have been proposed by academia and industry,these control strategies seldom take into account stochastic disturbances.Stochastic disturbances are usually considered as one of the sources of instability in induction motors systems,such as the voltage has stochastic surges and the external load is randomly switched,etc.In addition,the existence of magnetic saturation,torsional elastic moment and damping moment can make some induction motors parameters variable to a certain extent,for instance,self-inductance,mutual inductance,winding resistance and so on.These stochastic disturbances will influence the control accuracy,and even destroy the stability of the system.Therefore,it is of great theoretical significance and practical value to design a control strategy for induction motors to eliminate the influence of random disturbances and achieve accurate control of induction motors.In this paper,a new stochastic fuzzy adaptive control strategy for induction motors is designed,which combines command filtering technology and stochastic control theory.The quartic Lyapunov function is chosen as the stochastic Lyapunov function,and the fuzzy logic system and the command filtering technology are introduced to improve the backstepping method.Finally,the controller is designed by combining the backstepping method and the stochastic theory.In summary,the main research results of this paper are as follows:Firstly,the speed control problem of induction motors considering stochastic disturbance is studied.According to Ito formula,the stochastic system model of induction motors is constructed,and the controller is designed by combining backstepping and stochastic theory.Fuzzy logic system is used to approximate the stochastic non-linear function in the system,so that the traditional backstepping method can be applied to the non-linear system of asynchronous motor.The command filtering technique is used to solve the problem of calculation explosion,so as to overcome the huge burden of design and calculation caused by the traditional backstepping method.The control strategy proposed in this paper has better anti-interference ability,can overcome the influence of stochastic disturbance and achieve accurate control of induction motor,so it is more suitable for practical systems.Secondly,the input saturation limit is considered,and the speed control problem of induction motor considering stochastic disturbance under the input saturation limitation is studied.The quartic Lyapunov function is chosen as the stochastic Lyapunov function.Fuzzy logic system and command filtering technology are introduced to improve backstepping method,and compensation signal is introduced to eliminate filtering error.The designed controller can track the target signal quickly and effectively under saturated voltage limitation,and all state variables are bounded,so it has good robustness and control effect.Thirdly,the control strategy of induction motors based on dynamic surface technology is used to design a comparison,and MATLAB is used to verify the control strategy.The results show that compared with the control strategy of induction motor based on dynamic surface technology,the controller designed in this paper has higher control accuracy and better dynamic performance.