A Discrete-Time Repetitive Sliding Mode Control for Voltage Source Inverters

Voltage source inverters (VSIs), especially uninterrupted power supply for critical loads, require high steady-state performance, fast transient response, and strong robustness. However, it is difficult to achieve above requirements simultaneously by traditional control methods. A discrete-time repetitive sliding mode controller (DRSMC) with an exponential-based bi-power reaching law for three-phase VSIs is proposed, which combines the features of both the discrete-time sliding mode control (DSMC) and the repetitive control (RC) to achieve above requirements in VSIs. Furthermore, an exponential-based bi-power reaching law is proposed to further reduce the system chattering and improve the system dynamic response. The principle of equivalent control is adopted to integrate two methodologies and to facilitate the design and analysis of the proposed scheme. The discrete system equation of VSI is established. Voltage error and current error of capacitor are selected as the system state variables, and the DRSMC of VSI is designed with the proposed reaching law. Then RC is embedded into the forward error path of DSMC. The system equation of the DRSMC is deduced, the controller parameters are designed, and the system stability is analyzed. Finally, a 6-kW three-phase inverter setup is built to verify the effectiveness of the proposed method by comparing with DSMC and RC.