Speed-Sensorless Control Of Induction Motor Based On Improved Fractional Sliding Mode

Compared with other drive motors,induction motors are simple in structure,reliable in operation,rugged and durable,and easy to mass-produce.But the induction motor is a multivariable,strongly coupled nonlinear system.When the speed control system is affected by uncertainties such as parameter changes and load disturbances,the traditional PI control strategy is difficult to meet the actual control requirements.Sliding mode variable structure control has the advantages of low accuracy requirements,small calculation amount,strong robustness to system parameters and external disturbances,and is very suitable for high speed induction sensorless speed sensor vector control system.The fractional sliding mode combines the fractional calculus theory with the sliding mode variable structure control theory.Compared with the ordinary sliding mode control,the variability of the two degrees of freedom of the fractional calculus operation is increased,and the fractional calculus is used.Memory and genetic properties further improve the quality and performance of sliding mode control,and are more robust to systems with model uncertainties and external disturbances.However,the ordinary fractional-order integral sliding mode has a slow convergence rate and chattering problem near the sliding mode dynamics.In this regard,this paper proposes a design method to improve fractional sliding mode control.This control method introduces a terminal sliding mode term in the sliding surface to improve the dynamic performance of the fractional-order integrated sliding mode,and performs a second-order sliding mode design on the switching control to suppress chattering.Based on this method,the improved fractional-order sliding mode speed controller and flux linkage controller are designed to improve the performance of the induction motor vector control system.The simulation results show that the improved fractional sliding mode control method designed in this paper eliminates the chattering while taking into account the dynamic performance,and has certain advantages.Finally,an improved fractional-order sliding mode velocity observer is designed.The simulation results show that the improved fractional-ordersliding mode velocity observer has higher observation accuracy and dynamic performance than the common sliding mode observation method.Finally,a high performance improved fractional sliding mode speed sensorless vector control system is realized.