Research On Induction Motor Control Based On Fractional-order Sliding-mode Speed Estimation

High-performance vector-controlled induction motor has been widely used in the field of industrial control,because of its fast speed and torque response.In the vector control system,flux and speed are the essential signals to realize coordinate transformation and closed-loop speed control.But the issues which are affected by speed sensor installation,signal transmission and limited environment condition can influence control performance.Moreover it's hard to detect rotor flux by the sensors in practical applications.Therefore,speed sensorless control strategy is more and more widely used in the modern control field.Speed estimation method based on sliding-mode observer can improve the resistance against parameter disturbance and external interference,so it has been extensive applied in the industry field.The observer which integrated sliding-mode variable structure with fractional-order control has strong adjusting capability,high stability margin,better real time characteristic and rapid responsibility,and it also can eliminate the chattering phenomena which exist in traditional sliding-mode observer.The specific content is the research on induction motor control based on fractional-order sliding-mode speed estimation,the fractional-order sliding-mode observer is designed based on the advantages of fractional calculus theory and sliding mode control technique,stator voltage and current are used as input signals.The error between the measured and estimated stator current is utilized to define the sliding surface,and the control law of the observer is designed.The observer can estimate the rotor flux and speed of induction motors accurately,and it is applied to the vector control system for induction motor to improve the control performance.Analysis of the influence of parameter variation on the control system,the stator resistance and rotor time constant of induction motor are identified by the parameter identification method based on fractional-order sliding mode observer.According to the design of fractional-order sliding-mode observer,the simulation models are established based on Matlab/Simulink including the induction motor speed estimation,vector control system,stator resistance and rotor time constant identification,the correctness and validity have been verified.The simulation results are analyzed in comparison.The experiment results show that compared with the conventional integral sliding control method,the proposed method can estimate both the rotor flux and speed accurately,improve system performance and reduce the chattering phenomena efficiently.Stator resistance and rotor time constant identification can improve parameter robustness of the system.