Model Predictive-Sliding Mode Control for Three-Phase Grid-Connected Converters

This paper focuses on the implementation of an extended model predictive-sliding mode control (EMP-SMC) for three-phase grid-connected converters (GcCs). The proposed control considers the GcC model in the dq synchronous reference frame to forecast possible future behavior of the grid current. After that, the applied voltage vector is selected so that a predefined cost function is minimized. This function is aimed to reduce the grid current ripples during steady-state operation. Compared to the conventional MPC, the proposed EMP-SMC algorithm uses 19 voltage vectors (7 real voltage vectors and 12 additional virtual voltage vectors) for the prediction process. Accordingly, lower grid current THD and lower switching losses are obtained. However, the increase of voltage vectors number will lead to higher computation time delay that may affect the control performances. To overcome this problem, the proposed control uses a sliding mode-based preselection step that limits the prediction process to only ten voltage vectors at the most and a table-based implementation process that reduces significantly the execution time of the whole control algorithm. Simulation and experimental results are presented in order to show performances and effectiveness of the proposed EMP-SMC algorithm.