| Induction Motor(IM)is widely utilized in modern industrial factories and agricultural productions and daily life due to its benefits of steady performance,dependable operation,and easy maintaince.However,IM is an intricate control object with high order,sophisticated coupling,and multivariable properties which can be rapidly influenced by unpredictable factors like parameter changes and load disturbances.Therefore,the traditional control scheme is difficult to achieve high precision tracking control.At the same time,the discrete-time control method has some advantages over the continuous-time control method in reliability and system implementation,so the direct controller design using the discrete-time control method is of great significance in the IM speed and position tracking control system which is widely used in digital computer sampling.In addition,the traditional motor control algorithm based on the time-triggered mode,the controller runs according to the cycle,easy to lead to unnecessary data transmission and online double calculation.In some special application scenarios,such as the use of remote control unmanned submersible underwater operation,the personnel need to remotely operate the equipment on the surface of the water,the status feedback and control signal transmission distance is long,the periodic signal transmission is easy to cause the waste of system resources.Therefore,it is of great research significance to propose an effective control scheme for IM discrete-time system to achieve good tracking performance and save system resources.In this thesis,a discrete-time command filtered control strategy of IM based on fuzzy is proposed by combining command filtered backstepping method,fuzzy control,observer and event-triggered mechanism.The main research results are as follows:(1)For IM discrete-time system,an event-triggered controller is designed based on command filtered and fuzzy control technology.Firstly,command filter technology is used to solve the problem of "causality contradiction" caused by repeated difference of virtual control function.Meanwhile,a compensatory mechanism is added to lower the filter’s error and ensure the system’s control precision.Secondly,the fuzzy logic system is utilized to cope with the system’s unknown nonlinear function,which lessens the impact of the system’s unknown term.Finally,the event-triggered mechanism is constructed in the signal transmission channel between the controller and the motor,which reduces the controller’s online computing burden,saves system resources and is conducive to practical engineering applications.The simulation and experimental results demonstrate that the suggested control approach has a great tracking effect and can successfully reduce the controller’s updating times.(2)A novel observer-based command filtered fuzzy control strategy for IM discretetime system is studied.Firstly,a reduced order observer is designed to estimate the rotor angular velocity,which improves the reliability of the system.Secondly,by approximating the hyperbolic tangent function to the saturation function,the negative impact of voltage saturation on the system is reduced and the stability of the system is improved.The simulation and experimental results show that the proposed control method can accurately estimate the rotor angular velocity,avoid the influence of voltage saturation on the system,and achieve good tracking effect.(3)An event-triggered command filtered control strategy considering input saturation was studied for IM discrete-time systems.Through the design event-triggered condition,the transmission frequency between the system state feedback signal and the controller is reduced,so that the controller update can be connected with the state input of the system,and the voltage saturation problem is considered.Through simulation,comparative analysis,and experimental verification,the proposed control method can limit the motor voltage to a prescribed range.The event-triggered mechanism adopted can reduce the online computing burden of the system,save system resources,and achieve good tracking performance. |
