Observer-Based Discrete-Time Sliding-Mode Control for Single-Phase Current-Source Inverter

A discrete-time sliding-mode control (DSMC) scheme based on state predictive observer for single-phase current source inverter (CSI) is proposed. The state predictive observer estimates the state variables of the CSI one step ahead, so the discrete-time sliding mode controller generates the control signal one step ahead as well. Therefore, this approach compensates the time delay of DSMC, and it guarantees that the present control signal operates the present CSI system. According to the model of CSI, the state predictive observer is designed based on the pole-placement. Meanwhile, the discrete-time sliding-mode controller is constructed with the attenuating variable rate reaching law. The experimental results of a CSI prototype illustrate that the DSMC scheme with observer obtains better transient response than the DSMC scheme without observer. The time delay of DSMC is eliminated and the chattering is relieved. Furthermore, due to the state predictive observer, only the inductor current needs to be sensed for feedback control.