Robust Continuous Control Set Model Predictive Control in Synchronous Reference Frame for Grid-Tied Inverters

This article proposes a continuous control set model predictive control (CCS-MPC) for LCL-based grid-tied inverters. The proposed controller has inherent robustness against LCL resonance and does not need an active damping loop. The controller is designed in the synchronous reference frame where the variables are dc quantified. Otherwise, it can generate a steady-state offset in the stationary frame. The LCL model, which is needed for the CCS-MPC design, shows a strong cross-coupling between the dq axes, and the order of the model is high. To deal with the cross-coupling, a multi-input multioutput CCS-MPC is designed, and to reduce the order, system identification is used to build the process model. The optimization of CCS-MPC is performed offline, and a low real-time computation is needed. Moreover, the controller’s output is applied by a modulator, and it operates with a fixed switching frequency. To guarantee the closed-loop stability, the controller parameters are selected by a sensitivity analysis. The simulation and experimental results are presented to validate the proposed controller’s appealing features.