Behavior Properties And Stability Of Sliding Mode Control Systems With Quantized Feedback

Since the1950s, sliding-mode control (SMC) systems have been extensively researched and applied to solve many practical control problems due to their robustness to external disturbance and parametric variations with rather simple control structure. One of the significant advantages of sliding mode control is the complete compensation of the matched uncertainty which means the disturbance vector may be represented as a linear combination of the columns of control input channel. With the development of the network technology and the digital control, people try to combine the SMC theorem with digital control. Then the discrete-time SMC is emerged.In this thesis, the quantization behaviors of a sliding-mode control system with state feedback when the measurement of the state is quantized are studied. Some inherent dynamical properties for the quantized SMC systems are analyzed. The definition and the occurrence condition of’quantized sliding mode (QSM)’ are proposed. Properties of the system trajectories with quantized state feedback are characterized by using the concepts of QSM and quantized sliding-mode control (QSMC) system. We show that the QSM is piecewise constant.Quantization behaviors of equivalent control-based sliding mode control systems with matched disturbance are studied. The results of continuous-time QSMC systems are extended to discrete-time systems. Various simulations illustrate the behaviors of the QSMC system under uniform and logarithmic quantized state feedback.The permanent magnet synchronous motors (PMSM) are used to illustrate the theorem results proposed in this thesis. The simulation results of the PMSM controlled under the QSM controller and the finite-time controller are compared.