Linear Active Disturbance Rejection And Sliding Mode Control Of Asynchronous Motor System Based On AC-DC-AC Converter

The induction motor system based on AC-DC-AC converter is developing rapidly at home and abroad because it can achieve the bidirectional energy flow,realize the forward and reverse running state of the motor and the goal of speed regulation,ensure the dc bus voltage is constant and controllable,and the system can work at unit power factor.The whole system is composed of grid side subsystem,machine side subsystem and the direct current(DC)energy storage capacitor.The grid side subsystem is composed of power grid and ac converter,while the machine side subsystem is composed of DC-AC converter and induction motor.The main control objects are AC-DC converter and induction motor.For the induction motor system based on AC-DC-AC converter,the dc bus voltage changes greatly when the load changes in the side subsystem,and the adjustment is slow.The voltage overshoot and the energy flow between the network side subsystem and the machine side subsystem are analyzed.Through Vector Control,Linear Active Disturbance Rejection Control and Sliding Mode Control,the existing problems of the system are studied,and the Vector Control is taken as a comparative study.It mainly carries out the following work:Firstly,the development of induction motor system based on AC-DC-AC converter is studied.The working principle of the system is analyzed,and the system is built according to the mathematical model of the network side subsystem and the machine side subsystem.Secondly,the system vector control,the realization of the network side subsystem and the machine side subsystem of the independent control.On this basis,the method of adding load current feedback and capacitive current feedback into the network side subsystem is used to realize the coordinated control of the network side subsystem and the machine side subsystem.The Vector Control with feedback is compared with the independent control of the network side subsystem and the machine side subsystem.The results show that the coordinated control with feedback is better than the independent control on both sides of the netter in dc bus voltage control.Then,Linear Active Disturbance Rejection Control(LADRC)and Sliding Mode Control(SMC)are carried out respectively.The dynamic load current of the machine side subsystem is fed back to the outer voltage loop of the network side subsystem.So,the coordinated control of the network side subsystem and the machine side subsystem is realized.The simulation results of the two control methods are compared with the vector control.The results show that the LADRC and sliding mode control improve the system's anti-interference and reduce the voltage fluctuation of the dc bus.Finally,the model was built in MATLAB/Simulink environment.Vector control,LADRC and SMC are used in the AC-DC converter based on induction motor system.Simulation results show that the system has realized the energy can be the bidirectional energy flow between network side subsystem and machine side subsystem,induction electric motor and speed regulating brake operation state and goal,constant dc bus voltage control and network side subsystem can work in unit power factor control,such as the goal,the design of voltage soft given suppresses the voltage overshoot when the system starts.